SFS Annual Meeting

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Taxonomic precision use of diatom communities in hydrologically variable wetlands Diatoms are a common group of algae found in various waterbodies and can function as biological indicators. Species-level identification is both difficult and important allowing precision in assessment, community changes through time, and verification of record. Artificial ponds were studied at the former Bo Ginn National Fish Hatchery. Algae from eight ponds were sampled using a benthic core sampler and assessed at the laboratory. Five of the ponds were temporarily flooded and three had been permanently inundated. Standard protocol of diatom enumeration was applied to top and bottom core samples. Where diatoms were low in abundance and not countable, potentially there was growth of other primary producers. Temporary ponds had higher species richness. Evenness was low for most ponds. Highest Shannon diversity was 2.41 for a bottom core from a permanent pond. Comparing the top and bottom sediment, Shannon diversity varied from 0.246 to 0.412 in temporary ponds. Cocconeis placentula Ehrenberg dominated the bottom sediment of one of the permanent ponds and is a known epiphytic diatom on Cladophora glomerata (Linnaeus) Kützing. For five temporary ponds where top and bottom diatom communities were abundant, diatom diversity decreased through time. All samples were dominated by araphid chain forming diatom Staurosira construens Ehrenberg (relative abundance was always above 50%). This research contributes to knowledge on aquatic habitats transitioning from anthropogenic use to a new natural state and the ecology of common chain-forming diatom. Artificial systems that are no longer being used for aquaculture are harbors of biodiversity and should be further explored.

Anna Agi (Primary Presenter/Author), Georgia College & State University , anna.agi@bobcats.gcsu.edu;

Checo Colón-Gaud (Co-Presenter/Co-Author), Georgia Southern University , jccolongaud@georgiasouthern.edu;

Kalina Manoylov (Co-Presenter/Co-Author), Georgia College and State University , kalina.manoylov@gcsu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

FILAMENTOUS NON-HETEROCYTOUS CYANOBACTERIA AND GREEN MACROALGAE DOMINATE BENTHIC ALGAL MAT PROLIFERATIONS IN THE SHENANDOAH RIVER, VIRGINIA, USA The Shenandoah River recently experienced benthic cyanobacterial Harmful Algal Blooms (HABs) in addition to historical proliferations of filamentous green algae. This resulted in the closure of a 53 mile stretch of the North Fork of the river for much of the summer in 2021. In 2022, the General Assembly appropriated funds to study HABs in the Shenandoah River basin. These studies are being funded through the Virginia Department of Environmental Quality in collaboration with the Virginia Department of Health. These studies will focus on the environmental factors driving these HABs and management approaches that could prevent and mitigate their effects. During summer 2023, an in-depth study of benthic algal proliferations in river was initiated with the goal of characterizing the benthic algal and cyanobacterial composition. Quantitative benthic algal samples were collected monthly by Interstate Commission personnel on the Potomac River Basin from July through October from up to 10 sites across the North and South Fork of the river yielding a total of 27 samples. Chlorophyll a concentrations varied from 43-1422 mg/m2 . We identified 16 filamentous cyanobacteria genera belonging to Oscillatoriales and 22 genera of green and charophyte macroalgae including Cladophora, Spirogyra, Hydrodictyon, Rhizoclonium, Oedogonium, and Ulothrix. Cyanobacteria were distributed in all sampling stations during all sampling events. The most common and abundant mat-forming cyanobacterial species, capable of producing a variety of cyanotoxins, were Microseira wollei, and species of Oscillatoria, Microcoleus, Phormidium, Lyngbya, Geitlerinema and Anagnostidinema.

Jacob Mormando (Primary Presenter/Author), George Mason University , jmormand@gmu.edu;

Sydney Brown (Co-Presenter/Co-Author), George Mason University , sbrown88@gmu.edu;

Hannah Toney (Co-Presenter/Co-Author), George Mason University , htoney@gmu.edu;

G. Mike Selckmann (Co-Presenter/Co-Author), Interstate Commission on the Potomac River Basin , gmselckmann@icprb.org;

Charles O'Brien (Co-Presenter/Co-Author), Interstate Commission on the Potomac River Basin , cobrien@icprb.org;

R Christian Jones (Co-Presenter/Co-Author), George Mason University , rcjones@gmu.edu;

Rosalina Stancheva Christova (Co-Presenter/Co-Author), George Mason University , rchris13@gmu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

TAXONOMIC COMPOSITION AND PHOTOSYNTHETIC PIGMENTS OF PHYTOPLANKTON FROM THE SHENANDOAH RIVER, VIRGINIA, USA The Shenandoah River recently experienced benthic cyanobacterial Harmful Algal Blooms (HABs) in addition to historical proliferations of filamentous green algae. This resulted in the closure of a 53 mile stretch of the North Fork of the river for much of the summer in 2021. In 2022, the Virginia Department of Environmental Quality in collaboration with the Virginia Department of Health initiated studies with focus on the environmental factors that cause these HABs and management approaches that could prevent and mitigate their effects. During summer 2023, as an adjunct to an in-depth study of benthic algal mats in river, water column samples were collected by U.S. Geological Survey personnel at sites on both forks of the Shenandoah River above and below regions that have experienced major algal blooms in recent years to determine if the benthic mats were reflected in changes in water column algae. Water column samples were collected monthly from July through December 2023 by USGS personnel and shipped to GMU’s Potomac Environmental Research and Education Center for analysis. Initial examination indicates that phytoplankton samples were dominated by diatoms, green algae and cryptophytes, while cyanobacteria were rare and taxonomically different than the cyanobacteria species in the benthic mats. Chlorophyll a and pheophytin concentrations averaged 0.59 µg/L and 1.22 µg/L respectively indicating very low densities of suspended algal cells. Phycocyanin values were below detection limits, which is consistent with very low densities of cyanobacteria in the water column.

Rwan Alsaadi (Primary Presenter/Author), George Mason University , ralsaad2@gmu.edu;

Emma Boyden (Co-Presenter/Co-Author), George Mason University , eboyden@gmu.edu;

R Christian Jones (Co-Presenter/Co-Author), George Mason University , rcjones@gmu.edu;

Hannah Toney (Co-Presenter/Co-Author), George Mason University , htoney@gmu.edu;

Rosalina Stancheva Christova (Co-Presenter/Co-Author), George Mason University , rchris13@gmu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

IDENTIFYING THRESHOLDS AND OPTIMAL RANGES OF LIGHT FOR ALGAL GROWTH IN LARGE RIVERS Cyanobacteria harmful algal blooms (HABs) have increased in both occurrence and intensity in large rivers posing a risk to drinking water supplies, recreational use, and ecological stability. Although we have substantial information on how resources such as light and nutrients can affect algal growth, predicting algal blooms in large rivers is inherently more complex as duration and intensity of resources can continuously change in flowing water. This study examines how light influences riverine algal growth and promotes cyanobacteria dominance over other algae, such as green algae and diatoms. Water from the Cumberland River, Tennessee was incubated across a light gradient between 10 to 730 µmol m-2 s-1 in an environmental chamber, which identified minimum growth and nutrient uptake thresholds between 10 and 50 µmol m-2 s-1. Maximum algal biomass occurred at 550 µmol m-2 s-1. Cyanobacteria growth did not have a strong relationship with light intensity, but trended higher at higher light, suggesting that the optimal light intensity for cyanobacteria was greater than the eukaryotic algae. The results confirm that riverine HAB-forming cyanobacteria can have unique light requirements, and that vertical and horizontal light variation in flowing waters may be important in understanding HAB development in large turbid rivers. The next step of this project is to assess growth and toxin production across a larger light gradient and intermittent light availability that cells may experience with vertical movement in the river water column to identify optimal conditions, triggers of cyanobacteria dominance, and the effects of suboptimal conditions.

Dalton Tryba (Primary Presenter/Author), Tennessee Tech University , dtryba42@tntech.edu;

Jingjing Li (Co-Presenter/Co-Author), Tennessee Tech University , jingjingli@tntech.edu;

Justin Murdock (Co-Presenter/Co-Author), Tennessee Technological University , jnmurdock@tntech.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

BIODIVERSITY CONSERVATION IN THE FACE OF CLIMATE CHANGE: FUCOID MACROLAGE DYNAMICS ON BOSTON HARBOR ISLANDS In 2022, the Boston Harbor Islands were labeled among the eleven most endangered historic places in the U.S. due to climate change. Hosting crucial macroalgae, including Ascophyllum nodosum and Fucus spp., these species play a significant role in biodiversity by forming dense intertidal canopies that support diverse marine life. To assess the baseline distribution and density of these macroalgae, intertidal biodiversity data was collected and analyzed during the summer of 2023 from ten sites across five islands in the Boston Harbor: Gallops, Georges, Peddocks, Lovells, and Thompson. Island study sites were gridded into 48m wide areas with 9 quadrants spanning from the upper shore to low mean water. Within this sampling area, 33-38 0.5m2 quadrats were randomly placed for biodiversity surveys. In each quadrat, total counts of mobile invertebrates and percent cover of sessile invertebrates and macroalgae were evaluated. Gallops and Georges Islands exhibited high fucoid diversity (5 species) and were the exclusive islands with A. nodosum present. The frequency of fucoid species occurrence on these islands was 84% and 85%, respectively, while Thompson Island exhibited the least representation, and only two fucoid species were present, F. vesiculosus and F. spiralis at a frequency of 20%. Significantly higher species richness was observed in quadrats containing fucoid species than those without on Gallops Island (p = 0.03). Given the associated biodiversity and the abundance of fucoids on Gallops and Georges, these islands emerge as priorities for conservation efforts in the face of climate change threatening the Boston Harbor Islands.

Angel Checo Reynoso (Primary Presenter/Author), University of Massachusetts Amherst , achecoreynos@umass.edu;

Alysha Putnam (Co-Presenter/Co-Author), University of Massachusetts Amherst , aputnam@umass.edu;

Michelle Staudinger (Co-Presenter/Co-Author), University of Maine , michelle.staundinger@maine.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

DIATOM ASSEMBLAGES OF THE RIDLEY CREEK WATERSHED OVER 114 YEARS OF OBSERVATIONS Diatoms are routinely used as water quality indicators in inland waters, but long-term trends in their assemblage composition in lotic environments have not been investigated. Understanding long-term shifts in diatom assemblages is however important for separating the effects of environmental conditions from biogeographic processes such as spread of invasive species or extinction of native taxa. Historical diatom data are also essential for revealing secular trends in stream water quality associated with land-use transformation and climate change. This project seeks to compare historical diatom samples to recently collected samples from the Ridley Creek (Pennsylvania) watershed, which has been periodically sampled by the diatomists from the Academy of Natural Sciences of Philadelphia since 1909. Archived mounted specimens were enumerated alongside samples collected in 2023. Our results indicate a decrease in beta-diversity in recent samples, representing a progressive homogenization of diatom flora. The modern assemblages are dominated by eutraphentic diatoms characteristic for hard-water streams and vary depending on water temperature, dissolved oxygen content and to a lesser degree on substrate or season. In the past, assemblages varied dramatically among the sites indicating either very clean water or, alternatively, a pronounced organic enrichment. The current increase of some brackish and warm-water species appears to be a trend common for most streams of the Eastern Seaboard. These findings suggest dramatic differences in habitat quality over the last 114 years and could inform local and global conservation practices.

Sarah Barker (Primary Presenter/Author), Drexel University , sarah.m.barker728@gmail.com;

Lauren McGrath (Co-Presenter/Co-Author), Willistown Conservation Trust , lbm@wctrust.org;

Marina Potapova (Co-Presenter/Co-Author), Academy of Natural Sciences of Drexel University , mp895@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

The Influence of Nutrient Limitation in a Western Montana River Enhanced loading of nitrogen (N) and phosphorus (P) is pervasive in rivers around the world. As a consequence of nutrient-rich conditions, many well-lit rivers experience severe algal blooms, which pose a threat to water quality and aquatic habitat. We measured the short-term response of algal biomass to N and P additions across nutrient gradients in a Western Montana river. We hypothesized that the landscape position controlled the character of N and P limitation because gradients in nutrient input create biogeochemical domains that differ in chemical composition. Eutrophication of the Clark Fork River, located in Western Montana, is a major concern, reflecting enhanced nutrient loading of both N and P. Nutrient enrichment in the Clark Fork has increased the biomass of benthic algae, namely Cladophora glomerata, which routinely form extensive blooms during the summer growing season. During the late growing season of 2021 and 2022, we deployed four sets of nutrient diffusing substrates to assay potential nutrient (N, P, NP) limitation along 200 km of the Clark Fork River. After 16 days of incubation, chlorophyll-a accumulation among N-amended treatments (40-65mg/m2) and NP treatments (44-77 mg/m2) suggested N-limitation at three sites during the 2021 growing season. Effect sizes (treatment/control) and response ratios (ln[treatment/control]) exceeded threshold values indicating simultaneous and independent co-limitation. These measurements of potential nutrient limitation can be used to understand spatial and temporal controls of riverine algal blooms in the Clark Fork River and other mid-order rivers.

Matthew Nichols (Primary Presenter/Author), University of Montana , mn169338@umconnect.umt.edu;

H. Maurice Valett (Co-Presenter/Co-Author), University of Montana, Division of Biological Sciences , maury.valett@umontana.edu;

Michael DeGrandpre (Co-Presenter/Co-Author), University of Montana , michael.degrandpre@umontana.edu;

Robert O. Hall (Co-Presenter/Co-Author), Flathead Lake Biological Station, University of Montana , bob.hall@flbs.umt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

SPATIAL AND TEMPORAL PATTERNS IN PHYTOPLANKTON IN THE LOWER OHIO RIVER Freshwater ecosystems can be heavily affected by nutrient loading and subsequent changes in phytoplankton community composition, particularly harmful algal blooms that impact drinking water, recreation, and local economies. The Ohio River receives nutrients from both point and non-point sources and experiences large seasonal changes in discharge. In 2015 and 2019, extensive and severe blooms of Microcystis occurred in the Ohio River, prompting concerns about phytoplankton responses to nutrient loading and other environmental factors. Our goal in this study is to characterize phytoplankton communities within a 50-river-mile section of the Ohio River that spans from Cannelton, IN to Evansville, IN. Specifically, we documented spatial and temporal changes in phytoplankton in relation to river flow and nutrient stoichiometry. We collected samples seven times during the 2023 water year at three sites. Phytoplankton samples were quantified by PhycoTech, Inc. using a semi-automated Imaging FlowCytoBot. We analyzed community composition by functional group, primarily focusing on HAB-forming and non-HAB-forming cyanobacteria, diatoms, and other non-siliceous groups. Commonly observed taxa included Peridiniales (Dinophyceae), Skeletonema (Bacillariophyceae), and Cryptomonas (Cryptomonadaceae). Based on cell density, the most abundant cyanobacteria were Aphanocapsa/Aphanothece, though they never represented more than 8% of the sample biovolume. A clear transition occurred from mid to late summer, in which diatoms were replaced by cyanobacteria as the most abundant members of the phytoplankton. This transition was associated with reduced river flow and changing nutrient stoichiometry.

Tanya Iyer (Primary Presenter/Author), Indiana University Bloomington , tanya.l.iyer@gmail.com;

Lindsey Rasnake (Co-Presenter/Co-Author), Indiana University Bloomington , lrasnake@iu.edu;

Todd Royer (Co-Presenter/Co-Author), Indiana University , troyer@iu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Cladophora epiphyte community composition response to changing temperature Cladophora glomerata is a green filamentous macroalga, common in the South Fork Eel River (SFER), California, that supports a diverse biofilm of algal epiphytes. The Cladophora epiphytic microbiome plays an important ecological role in many ecosystems and has been identified as a model system for understanding microbiome processes. The microbiome associated with C. glomerata has a predictable successional sequence through the growing season in the SFER, facilitating study of factors that influence its form and function. To determine how temperature influences epiphyte structure, we incubated Cladophora in early (green, dominated by sparse Cocconeis), mid (yellow, dominated by denser Cocconeis, Gomphonema, and Rhoicosphenia), and late (red, dominated by Epithemia) stages of succession in microcosms subjected to three temperature treatments (ambient, +2.5°C, +5°C) over two weeks and assessed changes in epiphyte density and composition. In all temperature treatments, the abundance of cyanobacteria and Epithemia, an N-fixing diatom, increased over the experiment. The effect of temperature on epiphyte richness was similar in all successional stages. Preliminary results suggest that Shannon diversity increased with time in green and yellow stages across all temperatures but remained relatively constant in the red stage through time and across temperature treatments. Temperature-induced shifts toward cyanobacteria and/or Epithemia are likely to impact both food quality and N-fixation rates in the SFER. Combined, the changes we observed in the C. glomerata microbiome suggest that warmer conditions are likely to affect nitrogen availability and the ability of this microbiome to support consumers in this nitrogen-limited food web.

Chelsea Scheirer (Primary Presenter/Author), University of Alabama , cnscheirer@crimson.ua.edu;

Saeed Kariunga (Co-Presenter/Co-Author), Northern Arizona University , shk45@nau.edu;

Michael Zampini (Co-Presenter/Co-Author), Northern Arizona University , mcz39@nau.edu;

Jane Marks (Co-Presenter/Co-Author), Northern Arizona University , jane.marks@nau.edu;

Mary Power (Co-Presenter/Co-Author), University of California, Berkeley , mepower@berkeley.edu;

Steven Thomas (Co-Presenter/Co-Author), University of Alabama , sathomas16@ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

THE CURRENT FISH PROCESSING AND MARKETING OF LAKE TANA: REVIEW (SURVEY) SUMMARY In Lake Tana there are three commercially important ?sh species; African Cat ?sh, Nile tilapia and Labeobarbus spp.; which are available in whole fish or in the form of semi-processed products (fillet, gutted and dried fish). The fish from Lake Tana is harvested by motorized boats and tanqua. The fisher men are from different cooperatives /organized groups and individual fisher men. The harvested fish will be collected by traders from different location, cooperatives/Tana No. 1 Cooperative and FPME (Fish Processing and Marketing Enterprise). Tana No.1 cooperative and FPME are the major suppliers and processers of fish from Lake Tana. The major ?sh processing methods are gutting and ?lleting. The gutted and ?lleted are sold in Bahir Dar and Addis Abeba markets while the ?lleted cat ?sh is dried for sun drying or salting to be sold for Sudanese market and other regional and outside the region markets in the lowland areas. The traders supply fish for hotels, restaurants, other traders and consumers in the local market, Addis Abeba market, Sudan and other part of the country. As a result of the seasonality of the fisheries practice, the price of fish and fish products depends on season. Not only the season but also the price of fish and fish products fish species and the product type. Nile Tilapia accounts the highest price, the barbus and African cat fish follows respectively.

Tariku Hailu (Primary Presenter/Author), Agree , tahailu21@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Evaluating Fish Community Performance Across a Longitudinal Gradient in Novel Ecosystems Reservoirs are common anthropogenic ecosystems formed by impounding rivers. Reservoirs are managed for introduced or augmented populations of sport fishes, creating novel conditions for remnant riverine species. River-reservoir ecosystems (RRE) vary biologically, chemically, and physically across a longitudinal lotic to lentic habitat gradient from major inflows to the dam. While many attributes of free-flowing rivers are compromised following impoundment, habitats at reservoir inflows mimic conditions in unregulated river reaches, such as productive floodplains. Previous research in RRE has quantified changes in community structure among lacustrine, transition, and riverine zones, emphasizing the importance of ecotones at the lotic-lentic transition for supporting diverse and abundant assemblages. However, knowledge of how individual fish performance varies among habitats in RRE is understudied. To address this knowledge gap, I will evaluate how growth of early life stage fishes varies among zones of RRE relative to differences in food availability and habitat complexity. I expect growth rates of fishes to be highest at the transition zone as this area resembles productive floodplain habitat beneficial for rearing of early life stages. I will collect a suite of data in RRE across Ohio including fish communities, limnological variables, food availability, and habitat complexity throughout the summer growing season. I will use growth rates estimated from hard structures (otoliths) as a metric of performance. By understanding the relative benefit of different habitats to fish communities within novel ecosystems, this study will provide important information on factors contributing to species success in altered river ecosystems.

Justin Furby (Primary Presenter/Author), The Ohio State University , furby.5@osu.edu;

Casey Pennock (Co-Presenter/Co-Author), The Ohio State University , pennock.17@osu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

LIGHT AND TEMPERATURE AS DRIVERS OF ORGANISMAL METABOLISM IN FIVE SPRING-STREAMS ON ALASKA’S NORTH SLOPE. Arctic spring-streams on the North Slope of the Brooks Range in Alaska, USA experience extreme seasonal fluctuations in light but maintain relatively constant water temperatures. As food-web production and metabolism are closely tied to light availability and temperature, the decoupling of these two abiotic drivers in arctic spring-streams provides an opportunity to assess their individual effects on the energetics of consumers. We measured metabolic rates of Dolly Varden char (Salvelinus malma) and selected macroinvertebrate taxa from five spring-streams that form a thermal gradient of ~1 to 13?. Organisms were sampled during August and November 2023 and February and April 2024. Intermittent respiration rate measurements were conducted sequentially at five temperatures (3.0, 5.5, 8.0, 10.5, 13.0?) using an 8-channel respirometer (Loligo Systems®, Denmark). Organisms were then sacrificed for subsequent estimates of body mass, whole-body lipid content, total energy-content, and tissue ?13C and ?15N. To date, respiration rates have been measured from 38 individual S. malma, 43 stoneflies (Isoperla petersoni), and 35 amphipods (Gammarus sp.). Preliminary data show that resting metabolic rates of S. malma are highest at the coolest (~3?) and warmest (~13?) experimental temperatures, with lowest metabolic rates of ~41 mg O2/kg/hr and peaks of ~121 mg O2/kg/hr. These experiments are ongoing and will include further respirometry measurements and body composition analyses to assess potential physiological responses to differences in temperature and light regimes.

Adam C. Hensley (Primary Presenter/Author), The University of Alabama , hensley.adam4@gmail.com;

Alexander D. Huryn (Co-Presenter/Co-Author), The University of Alabama , huryn@ua.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama , jbenstead@ua.edu;

Carla L. Atkinson (Co-Presenter/Co-Author), The University of Alabama , carla.l.atkinson@ua.edu;

Tori A. Hebert (Co-Presenter/Co-Author), The University of Alabama , tahebert@crimson.ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Interannual Comparison of Juvenile Alewife Age and Growth in Eastern Massachusetts (USA) Alewife (Alosa pseudoharengus) are anadromous fish that migrate between freshwater and marine environments, spawning in freshwater rivers and lakes and spending their adult lives in the ocean. Limited information is known regarding the characteristics of successful juvenile emigrants and the importance of access to estuary habitat for juvenile growth and survival. During July 2021 and 2022 we used pelagic purse seines to collect juvenile river herring from Whitman's Pond and the Weymouth Back River in Weymouth, Massachusetts (USA). Actively emigrating juveniles were also collected downstream of Whitman's Pond during their emigration. We counted daily growth increments using sagittal otoliths to determine estimates of age and growth among sample locations over time. Preliminary results from 2021 suggest that juvenile river herring sampled from estuary habitat display higher growth rates than lake resident fish, potentially due to greater resource availability in the marine environment than in lake habitat. Age and growth comparisons between actively emigrating and lake resident fish will provide important context for understanding characteristics of fish choosing to emigrate, and allow for a more nuanced interpretation of growth for fish collected within estuary habitat. The results of this research will contribute to a greater understanding of juvenile river herring emigration and estuary habitat use dynamics and will inform population modeling efforts by providing valuable age and growth information during habitat transitions during early life history stages.

Adamaris Agosto (Primary Presenter/Author), University of Massachusetts Amherst , aagosto@umass.edu;

Allison Roy (Co-Presenter/Co-Author), U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts Amherst , aroy@eco.umass.edu;

Adrian Jordaan (Co-Presenter/Co-Author), Department of Environmental Conservation, University of Massachusetts, Amherst , ajordaan@eco.umass.ed;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Comparing Juvenile River Herring Growth in two Coastal Massachusetts Lakes Alewife (Alosa pseudoharengus) and Blueback Herring (A. aestivalis) are anadromous fish species that spawn in freshwater where juveniles grow for ~3–6 months before emigrating to the ocean where they reside until reaching adulthood. Collectively referred to as river herring, their populations have declined drastically over the past centuries due to overfishing, habitat loss from damming, and pollution. Previous research suggests that juvenile river herring population densities in freshwater lakes significantly affect their growth and survival, but limited information exists regarding intra-annual variation in growth that occurs among early and late hatching juvenile river herring cohorts in freshwater lakes with different species compositions and population densities. We compared juvenile river herring growth rates among the months of June, July, and August 2022 in two freshwater lakes in coastal Massachusetts (USA). We deployed nighttime pelagic purse seines to sample juvenile river herring in Chebacco Lake (low-density, Alewife-only) and Upper Mystic Lake (high density, Alewife and Blueback Herring). Juvenile river herring were enumerated in the field and a subset from each sample date were retained for age and growth analysis using sagittal otoliths. We predict that growth rates will be greatest earlier in season and trend down in the high density, mixed species system (Upper Mystic Lake) due to competition for prey. We also predict that monthly growth rates will remain constant in the low density, Alewife-only system (Chebacco Lake). Results from this research will be used to inform management strategies that maximize juvenile river herring growth and survival in freshwater nursery habitats.

Grace Davis (Primary Presenter/Author), Department of Environmental Conservation at University of Massachusetts, Amherst , gndavis@umass.edu;

Allison Roy (Co-Presenter/Co-Author), U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts Amherst , aroy@eco.umass.edu;

Adrian Jordaan (Co-Presenter/Co-Author), Department of Environmental Conservation, University of Massachusetts, Amherst , ajordaan@eco.umass.ed;

Julian Burgoff (Co-Presenter/Co-Author), Department of Environmental Conservation at University of Massachusetts, Amherst , jburgoff@umass.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

INFLUENCE OF ROAD CULVERTS ON FISH SPECIES COMPOSITION IN PENNSYLVANIA STREAMS Culverts are known to reshape and impact various abiotic and biotic features of streams, such as the distribution, migration, and genetic diversity of different species of fish. However, relatively little is known about how culverts impact fish community composition, particularly regarding non-game fish species upstream of culverts. In this study, we analyzed fish species composition upstream and downstream of culverts from 22 streams sampled between 2015 and 2023. On average, we found nearly two more species downstream (mean = 4.2 species) of culverts than upstream (mean = 2.3 species; paired t-test, p<0.001). Creek chub and blacknose dace were found upstream of culverts at about 75% of the streams where they were present, whereas redside dace, fantail darter, and white sucker were recorded upstream in less than 30% of streams. Sculpin, brook trout, and brown trout were found upstream of culverts at about half of the sites where they were present. The different responses among species may indicate that stream fragmentation by culverts has stronger impacts on some fish species than others, perhaps due to differences in relative abundance. Our results support that stream fragmentation by culverts negatively impacts fish diversity and suggest that severity of impact differs among fish species.

Hannah Condon (Primary Presenter/Author), Indiana University of Pennsylvania , hannahmcon01@gmail.com;

David Janetski (Co-Presenter/Co-Author), Indiana University of Pennsylvania , janetski@iup.eud;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Developing a Geospatial Database to Address Migratory Fish Conservation Needs in Pennsylvania Streams The Unassessed Waters Initiative (UWI) has been collecting data on the presence and distribution of brook trout (Salvelinus fontinalis) throughout Pennsylvania since 2010. Thousands of streams have been assessed for fish assemblage characteristics and chemical water quality. These data could be critical not only for prioritizing waters for protection, but also for better understanding factors affecting brook trout population resilience at a larger scale and in a geospatial context. Physical barriers to dispersal and impaired chemical water quality are two widespread problems for brook trout populations in central Pennsylvania. The North Atlantic Aquatic Connectivity Collaborative (NAACC) has been cataloging the location, type, and conditions of road crossings throughout Pennsylvania. Further work could be done to increase the rate of physical barrier assessments throughout Pennsylvania, particularly if targeted using information from the UWI to focus on areas of concern for brook trout. Further, the Alliance for Aquatic Resource Monitoring (ALLARM) is a citizen-science backed effort to catalog and monitor chemical water quality covering wide areas of Pennsylvania. While the database has grown since its inception and is currently publicly available for scientific use, these data again are not integrated with other statewide databases and could be enhanced using geospatial technologies. To aid in investigations of conservation needs for brook trout, we developed an accessible, easily managed database containing fish occurrence, chemical water quality, and road crossing/stream barrier information for the state of Pennsylvania that may be useful in address conservation needs for other species of interest (e.g., American eel, Anguilla rostrata).

Leslie Rieck (Primary Presenter/Author), Lycoming College , rieck@lycoming.edu;

Sofia Odoemena (Co-Presenter/Co-Author), Lycoming College , odosofi@lycoming.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Variation in Size of Fish Across the Arizona Verde River Across the southwestern United States, streamflow has been declining in recent decades, causing habitat loss for native fishes. In the Verde River basin of Arizona, there are concerns that flow will continue to decline due to water withdrawals for human use. In order to make effective conservation plans, we need to better understand the current distribution of fish populations in the Verde River and how they might change with loss of flow. Our initial study question is: "How does the size of native and non-native fish species change with river miles along the Verde River?" We used a combination of field survey data from summer 2023 with previously collected fish data from prior years to quantify the distribution and sizes of adult fishes across the Verde River. Our preliminary findings reveal variance in fish size (i.e., total length) at different river miles along the Verde River, with both increases and decreases in mean size of adults observed moving down the river network. This pattern suggests that factors beyond geographical location are influencing the size of adult fishes, and these influential factors could include stream flow dynamics, seasonal variation, and physical habitat characteristics. Our next steps will be to include seasonality, stream flow, and local measurements of width and depth in models to predict adult fish size for specific native and non-native species. These future studies will contribute to a better understanding of the habitat needs of native fish species to ensure their conservation in the Verde River ecosystem.

Sydney Ingham (Primary Presenter/Author), University of Arizona , sydneyingham@arizona.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

FRESHWATER CSI: CHINOOK SALMON LIFE-HISTORY INFLUENCES HOW DIAGNOSTIC STRUCTURES RELATE TO FISH LENGTH Bones and similar structures can provide information on the species and estimated sizes of decomposed or digested fishes. This information can be used to expand information on ingested prey, archeological remains, or damaged specimens. However, relating these diagnostic structures to attributes like size requires knowledge of the target relationships from whole fish. Here, four cranial bones (cleithra, dentaries, and opercles) and otoliths, collectively ‘diagnostic bones’, were extracted, cleaned, and measured from whole juvenile Chinook Salmon, Oncorhynchus tshawytscha. We used linear regressions to establish fork length relationships for multiple measurement axes of these diagnostic bones for three distinct groups: hatchery, naturally produced, and surrogate juveniles. These groups were all sourced from the Willamette Basin, Oregon, but represent unique growth trajectories. Our findings of strong correlations (>80%) between all measured bones and fish lengths support the use of bones as a diagnostic tool in estimating lengths. However, despite this strong support for the use of diagnostic bones generally, regressions were unique to each group. Our observations highlight the need for population and life history specific allometric data when constructing regression models to ensure they are representative of the target population.

Keiara Pham (Primary Presenter/Author), University of Maine , keiara.pham@maine.edu;

Christina A. Murphy (Co-Presenter/Co-Author), U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit, Orono, ME , christina.murphy@maine.edu;

Jeremy Romer (Co-Presenter/Co-Author), Oregon Department of Fish and Wildlife, Springfield District Office, Springfield, Oregon, USA , jeremy.d.romer@odfw.oregon.gov;

Kevin Stertz (Co-Presenter/Co-Author), Oregon Department of Fish and Wildlife, North Willamette Watershed District Office, Clackamas, Oregon, USA , kevin.a.stertz@odfw.oregon.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Scale-dependent tradeoffs between habitat and time in explaining Alligator Gar (Atractosteus spatula) movement Ecological theory predicts that movement by riverine fishes at the population level is characterized by both stationary and mobile individuals together creating a leptokurtic distribution of movement distances. However, studies testing this theory typically ignore spatial heterogeneity in riverscapes and the theory has not been tested using Alligator Gar (Atractosteus spatula), a species of growing interest among anglers and fisheries managers alike. We characterized movements and habitat associations of Alligator Gar in the Brazos River, Texas, at fine (every two hours for 24 hours) and coarse (every month for 16 months) spatiotemporal scales. We tested for the presence of leptokurtosis and relationships between movement distance, habitat dissimilarity, and time-at-large using multivariate and univariate statistical approaches. Dispersal by Alligator Gar revealed leptokurtosis at the coarse scale but not the fine scale. At the fine scale, mixed effects quantile regression revealed there was no relationship between habitat dissimilarity and dispersal distance, but dispersal was positively correlated with time. At the coarse scale, dispersal was positively correlated with increased habitat dissimilarity and time, but only for the most mobile individuals. Our work suggests that short-term movements by riverine Alligator Gar during warm seasons and at base flows increased with time but were unrelated to habitat, while long-term movements over an annual cycle during warm season flow pulses revealed highly mobile members of the population accessed distant and novel floodplain environments.

Johnathan Ellard (Primary Presenter/Author), Texas A&M University , jellard@tamu.edu;

Hayden Roberts (Co-Presenter/Co-Author), Texas A&M University , hcr@tamu.edu;

Dan Daugherty (Co-Presenter/Co-Author), Texas Parks and Wildlife Department, Inland Fisheries Division , Dan.Daugherty@tpwd.texas.gov;

Matthew Acre (Co-Presenter/Co-Author), U.S. Geological Survey, Columbia Environmental Research Center , macre@usgs.gov;

Joshuah Perkin (Co-Presenter/Co-Author), Texas A&M University , jperkin@tamu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Dams, diets, and diversity: food webs in tailwater fisheries Sections of river downstream of dams are highly altered by changes in flow and temperature regimes. These alterations, in turn, negatively impact invertebrates, such as sensitive EPT taxa (insects in Orders Ephemeroptera, Plecoptera, Trichoptera) that are important sources of food for higher trophic levels, like fish. While the influence of dams on invertebrates have been explored in detail, the propagation of these effects through the food web has been less studied. To address this, our study examined fish diets downstream from multiple dams throughout the upper Colorado River basin in 2022-2023. We predicted that the diversity and composition of prey items in fish diets would be altered by dams, and specifically anticipated to find an increase in invertebrate diversity and higher numbers of EPT taxa in fish diets as distance from the dam increases. Rainbow and Brown trout diets were collected at two downstream locations (~1km, ~3-5km) in the Blue, Colorado, and Taylor Rivers using electrofishing and gastric lavage. In the laboratory, invertebrates from diet samples were counted, measured, and identified. Invertebrate richness, Shannon diversity, and the proportion of EPT taxa were then estimated for each fish diet, averaged across fish and rivers, and compared between upstream and downstream locations. We found that diets that were collected nearest dams had lower diversity of invertebrate prey (richness: p<0.001; Shannon diversity: p<0.01) and fewer EPT taxa (p<0.001) compared to those collected further downstream. Our results indicate that dams reduce the diversity of feeding interactions that underpin economically and recreationally important tailwater fisheries.

Gabriel Michael Smith-nez (Primary Presenter/Author), USGS, Coconino Community College , gmsmithnez01@gmail.com;

Eric Scholl (Co-Presenter/Co-Author), U.S. Geological Survey , escholl@usgs.gov;

Morgan Ford (Co-Presenter/Co-Author), usgs , mford@usgs.gov;

Ted Kennedy (Co-Presenter/Co-Author), USGS Southwest Biological Science Center, Grand Canyon Monitoring and Research Center , tkennedy@usgs.gov;

Charles Yackulic (Co-Presenter/Co-Author), USGS Southwest Biological Science Center, Grand Canyon Monitoring and Research Center , cyackulic@usgs.gov;

Dan Kowalski (Co-Presenter/Co-Author), Colorado Parks and Wildlife , dan.kowalski@state.co.us;

Robert Zuellig (Co-Presenter/Co-Author), U.S. Geological Survey , rzuellig@usgs.gov ;

Daren Carlisle (Co-Presenter/Co-Author), U.S. Geological Survey , dcarlisle@usgs.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Integrating biotic measures to barrier assessment prioritization Stream crossing structures such as culverts can prevent fish passage, reducing individual fitness and population viability. To most efficiently prioritize watersheds for barrier removal assessment, we must understand biotic and abiotic conditions influencing barrier severity. These conditions are complex and varying significantly across watersheds. While the removal of barriers can benefit native species, the restoration of connectivity can facilitate the dispersal of nonnative species; therefore the composition of nonnative species should be considered when prioritizing barriers for removal. This process can be aided by using landscape scale variables predicting severity of passage barriers as well as native/nonnative species composition. Therefore, the objective of this study was to quantify how subwatershed scale environmental and human variables are related to both stream-crossing barrier severity and native/nonnative biodiversity measures. Barrier severity scores were acquired from the Southeast Aquatic Resources Partnership aquatic barrier inventory. Biodiversity measures were derived from stream segment scale fish community data. We used generalized linear models to predict both barrier severity metrics and biodiversity values using environmental and human variables. The utility of this prioritization system is that managers can focus resources on watersheds that will benefit the most from barrier assessments while minimizing potential impacts of facilitating spread of aquatic invasive species.

Ridge Sliger (Primary Presenter/Author,Co-Presenter/Co-Author), Clemson University , rsliger@clemson.edu;

William Annis (Co-Presenter/Co-Author), Clemson University , wannis@g.clemson.edu;

Lily Thompson (Co-Presenter/Co-Author), Clemson University , lilyt@g.clemson.edu;

Brandon Peoples (Co-Presenter/Co-Author), Clemson University , Peoples@g.clemson.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Assessing crayfish species diversity in the Lower Ogeechee River Basin We sampled crayfish species in the Lower Ogeechee River Basin with the goal of assessing the diversity and distribution of these organisms and updating the status of the rivers’ lone endemic crayfish species. Specimen collections were conducted in June-July 2023 at seven distinct locations, resulting in a total of 71 individuals. These specimens were subjected to morphological analyses to determine genus and species classification. To ensure the accuracy of taxonomic identifications, genetic analysis targeting a portion of the mitochondrial COI gene was performed, facilitating the creation of a phylogenetic tree. The genetic analysis revealed the presence of nine distinct crayfish species belonging to three genera. Of particular interest were two species: Procambarus petersi (Ogeechee River crayfish), the river's only endemic crayfish, and Lacunicambarus diogenes (devil crayfish), a species not previously documented within this river system. This study provides valuable insight into the crayfish diversity and distribution in the Ogeechee River Basin. These findings underscore the ecological importance of these species in the region. Continued efforts to monitor and document these crayfish populations will contribute to the state's natural resources records and aid in devising effective conservation strategies for the river ecosystem.

Luis Miguel Acevedo Soto (Primary Presenter/Author,Co-Presenter/Co-Author), Universidad de Puerto Rico at Mayagüez , luis.acevedo46@upr.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Freshwater Snail Inventory of the Upper Delaware River Freshwater snails are a relatively understudied component of the Upper Delaware Scenic and Recreational River (UPDE). The Academy of Natural Sciences partnered with UPDE to inventory and assess the distribution and abundance of freshwater snails in the Upper Delaware River. UPDE consists of a variety of temperature designations and therefore the focus of this project is the comparison of the freshwater snail community in the coldwater section, the warmwater section, and the transitional area near Callicoon, NY. The current collection consists of almost 20,000 snails representing 9 Gastropod families, most of which were found in the river's warmwater regions. Barcoding of the CO1 gene was utilized to identify species. Japanese Mystery snails, which are an invasive species requiring more research on their impact on other snail species and the broader ecosystem, were included in our findings. The data produced from these sections of the river will help to inform decisions regarding dam releases and flow management practices with the partners of UPDE.

Emma Guelzow (Primary Presenter/Author), Academy of Natural Sciences , elg79@dragons.drexel.edu;

Noelle Raezer (Co-Presenter/Co-Author), Academy of Natural Sciences , nr648@drexel.edu;

Tanya Dapkey (Co-Presenter/Co-Author), Academy of Natural Sciences , thd45@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Nematode communities associated with springs in the Namib Desert of Namibia In desert environments, groundwater springs are microhabitats that provide critical water resources to animal and plant life, although they can be saline due to high rates of evaporation. The Namib Desert of Namibia in southern Africa contains many desert springs whose biodiversity has rarely been investigated. We studied the diversity and abundance of sediment and mat nematodes in 84 samples collected from seven desert springs in the central Namib Desert. Spring length at the time of sampling ranged from 43 – 658 m, and depth ranged from 0.4-13.2 cm. At each sampling location, water pH electrical conductivity, DO were measured. Nematodes were extracted from each sample, quantified, and identified (family-level). Electrical conductivity averaged 56 mS/cm and generally increased along the course of each spring, exceeding 500 mS/cm in some locations. DO was high in all samples, averaging 11.8 mg/L, and pH ranged from 6.5-9. Nematodes were found in all but four samples, and their abundance was not correlated to salinity or pH, ranging from 0 - 47,666 nematodes/100 g fresh sediment or algal mat material. Mats and sediment communities were similar to each other. Each spring hosted a distinct subset of nematode taxa, with some overlap with other sites. The most frequently found taxa included Rhabdolaimus, Monhystrella, Ethnolaimus (all bacterial-feeders), and Trypila (a predator).

Amy Treonis (Primary Presenter/Author), University of Richmond , atreonis@richmond.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Phenology of invertebrate communities above the water line in a subtropical wetland Terrestrial and aquatic habitats contribute to feeding opportunities of insectivorous birds in riparian and marsh habitats. The phenology of arthropod abundance from these sources are poorly described in the context of hydrological and fire management and is likely to be sensitive to changing climatic conditions. We quantified community dynamics of invertebrates above the water on emergent vegetation (primarily Cladium jamaicense) at three short-hydroperiod (max depth = 35 cm, approximate hydroperiod = 7 months) subtropical marshes of the Florida Everglades. Monthly collections of invertebrates were conducted over one hydrologic year (July 2022 – June 2023) by sweeping emergent vegetation with a muslin hoop-frame sweep net for one 10-min transect each visit. We collected 3,586 invertebrates from fourteen different orders including emergent aquatic insects and terrestrial invertebrates living on the emergent vegetation. Rank abundances of orders accounting for 95% of the total catch were Araneae (55%), Diptera (16%), Hymenoptera (7%), Gastropoda (5%), Coleoptera (5%), Hemiptera (4%), and Odonata (3%). Peak abundance of emergent Ephemeroptera occurred in the late wet season (November) and differed from Odonata peak abundance in the dry season (February). Spiders (Araneae) abundance peaked in the late wet season (November) at the same time as peak abundance of Ephemeroptera and near-peak abundance of Diptera. Terrestrial herbivores reached peak abundances in the late dry season (March) before surface water returned in May. This poster will highlight temporal changes in the production of aquatic and terrestrial invertebrates and relate them to hydrologic and climatic variables.

Alan Mock (Primary Presenter/Author), Florida International University , amock003@fiu.edu;

Joel Trexler (Co-Presenter/Co-Author), Florida State University , jtrexler@fsu.edu;

Nathan Dorn (Co-Presenter/Co-Author), Florida International University , ndorn@fiu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Using Stable Isotope Analysis to Investigate the Trophic Ecology of Aquatic Beetles and Hemiptera Aquatic insects provide important ecosystem services such as pest control, nutrient cycling, and organic matter breakdown. Aquatic insects also support larger organisms in the aquatic food web such as fish, waterfowl, and amphibians. While it has been reported that overall insect biodiversity is declining, little is known about the status and distribution of pond insects. Despite their ecosystem services, importance to the aquatic food web, and unknown conservation status, much of their basic ecology is also uncertain and may be needed to inform future conservation plans. Functional feeding groups, based on feeding strategy and morphology, for aquatic insects have been described, but specifics such as diet and trophic position are under studied, particularly in lentic ecosystems. Stable isotope analysis (SIA) is an efficient tool and has been used in previous trophic ecology studies. We are using C13 and N15 stable isotopes to estimate the diet items and trophic position of common aquatic insect species, mainly from the orders Coleoptera and Hemiptera from ponds in Northern Louisiana. Preliminary results from this study have estimated that most species from Dytiscidae, Corixidae, Notonectidae, and Gerridae ranged in trophic levels 1.93-2.62 (primary to secondary consumers), and one species of Dytiscidae (Thermonectus basillaris basillaris) had the highest trophic position (4.03: predators). These results were contrary to our predictions that species of Notonectidae would occupy the highest trophic level. Future results will contribute new information on species’ diet, species’ distributions, and trophic dynamics in ponds.

Shelby Medlock (Primary Presenter/Author), Louisiana Tech University , sam135@email.latech.edu;

Julia Earl (Co-Presenter/Co-Author), Louisiana Tech University , jearl@latech.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Spatial and Temporal Variability of Macroinvertebrates in a Regulated Prairie River Macroinvertebrates are useful indicators of water quality, and metrics of diversity and community composition are often used for environmental compliance. This research is focused on quantifying baseline spatial and temporal variation in macroinvertebrates that will be used to assess the environmental impacts of water management in the Kansas River basin. Specifically, the U.S. Army Corps of Engineers is planning a water injection dredging (WID) demonstration to manage sediment accumulation in a large reservoir on the Big Blue River. The WID demonstration is expected to increase suspended sediments downstream into the Kansas River. Samples were collected in Summer-Fall 2023 using 1hr D-net surveys at five study sites; one in the Kansas River upstream of the confluence with the Big Blue River, one in the Big Blue River and the other three downstream in the Kansas River. Using ordination methods, we observed distinct spatial variation in community composition with samples in the Big Blue River dominated by water column taxa such as corixids and zooplankton. Surface insects (Veliidae) characterized communities at the control site, and the highest diversity of benthic insects occurred at sites downstream of the confluence. Although we captured important spatial variation to consider while assessing environmental impacts of WID, drought conditions in 2023 might limit contrasts of years with higher water availability, thus another year of baseline sampling is planned for 2024.

Ariana Martinez (Primary Presenter/Author), Kansas State University , ariana6105@gmail.com;

Keith Gido (Co-Presenter/Co-Author), Kansas State University , kgido@ksu.edu;

Logan Rowley (Co-Presenter/Co-Author), Kansas State University , lrowley@ksu.edu;

Laura Totten (Co-Presenter/Co-Author), US Army Corps of Engineers , laura.a.totten@usace.army.mil;

Marvin Boyer (Co-Presenter/Co-Author), Army Corp of Engineers , marvin.g.boyer@usace.army.mil;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

HOW COLONIZATION CONDITIONS AFFECT MACROINVERTEBRATE COMMUNITY STRUCTURE IN STREAM MESOCOSMS Determining how colonization conditions affect the structure of macroinvertebrate communities in stream mesocosm studies is important for experimental design and understanding relevance of exposure tests. Until recently, there has been only a qualitative understanding of the potential effects of different colonization conditions upon studies at the USEPA Experimental Stream Facility. This study tested three different mesocosm colonization conditions: 1) high inflow of river water (RW) (34 L/min), 2) low inflow of a mixture of RW and reverse osmosis (RO) water (1.4 L/min), and 3) the same low RW/RO inflow (1.4 L/min) with the addition of field collected macroinvertebrates transferred in a 1:1 ratio of stream benthos to mesocosm area. This last colonization protocol has been used since 2011 to colonize mesocosms to mimic less impacted background water quality and to make experimental dosing objectives logistically tractable. Study results showed that the lower inflow RW/RO condition decreased the total abundance and diversity of the communities by 70% and 63%, respectively. However, when augmented with the direct transfer of field organisms, these losses were largely compensated for. With the field transfers, total abundance was greater (by 150%) and diversity was only 25% lower than the higher RW-only treatment. The field transfer increased the average abundance of caddisflies by a factor of 10 and doubled that of mayflies, two larval insect groups considered important for dosing studies. Therefore, the protocol used since 2011 appears to be a reasonable approach.

David Speth (Primary Presenter/Author), University of Dayton , davidspeth5903@gmail.com;

Christopher Nietch (Co-Presenter/Co-Author), U.S. Environmental Protection Agency , nietch.christopher@epa.gov;

Roger Yeardley (Co-Presenter/Co-Author), U.S. Environmental Protection Agency , yeardleyroger@epa.gov;

Paul Weaver (Co-Presenter/Co-Author), U.S. Environmental Protection Agency , weaver.paul@epa.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Determining diet variation among Arkansas winter stonefly species (Capniidae: Allocapnia) using stable isotope analysis Arkansas has twelve Allocapnia stonefly species, many of which are threatened. Allocapnia are classified as detritivore-shredders, but they may also ingest stream autotrophs and the presence of multiple species within a stream suggests that there may be interspecific differences in feeding habits allowing them to coexist. The objective of this study was to determine the relative contributions of allochthonous and autochthonous food resources to the diets of two common Allocapnia species, A. mohri and A. rickeri, and the rarer A. jeanae, which is designated as a species of greatest conservation need in Arkansas. Five sites representing low order, headwater streams known to have more than one species present were sampled for adult stoneflies, leaf litter, and algae during December 2022 and January 2023. Allocapnia adults were identified to species level before undergoing stable isotope analysis for d15N and d13C values along with leaf and algae samples that would serve as end member food resources in the mixing model. A single-isotope (?13C), two-source mixing model was used to determine relative food resource importance for each species. Intraspecific variation across sites was significant across species. Diet differed between species (A. mohri and A. rickeri) at one site; however, these values fell outside of the isotopic range of the two sources sampled, indicating a different food source entirely. The majority of Allocapnia species analyzed appeared to rely primarily on detritus. Autochthonous contributions ranged from 8 to 47 percent across species and sites, and may be based on resource availability related to canopy cover.

Isabelle Pillow (Primary Presenter/Author), Virginia Commonwealth University , pillowisabelle@gmail.com;

Jonathan Novotny (Co-Presenter/Co-Author), University of Arkansas , n/a;

Michelle Evans-White (Co-Presenter/Co-Author), University of Arkansas , mevanswh@uark.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

The Effects of Humidity on Aerial Dispersal in a Crawling Water Beetles (Coleoptera: Haliplidae) Environmental changes such as warming and drying disrupt aquatic habitats, creating challenges for aquatic insect populations. Some aquatic insects use aerial dispersal to escape the increasing temperature and decreasing water level associated with droughts, but little is known about the effect of humidity on dispersal capacity. We conducted a laboratory experiment that manipulated humidity and water level and recorded aerial dispersal in a common and widely distributed aquatic crawling water beetle, Haliplus punctatus (Coleoptera: Haliplidae). We found that beetles were more likely to disperse as humidity increased. By day four of the experiment, 2.7 times more beetles dispersed in the high humidity treatment than in the low humidity treatment. Our results suggest that, although beetles are capable of flying away from drying habitats, aerial dispersal may be less likely to occur under drought conditions, when humidity is low. Understanding the impact of environmental cues on aquatic invertebrate behavior is crucial for comprehending how these species will respond to global climate change.

Hope Romero (Primary Presenter/Author), University of San Diego , hoperomero@sandiego.edu;

Zoey Clark (Co-Presenter/Co-Author), University of San Diego , zclark@sandiego.edu;

Margaret Jelsma (Co-Presenter/Co-Author), University of San Diego , mjelsma@sandiego.edu;

Samantha Lopez-Diez (Co-Presenter/Co-Author), University of San Diego , slopezdiez@sandiego.edu;

Teigen Christiansen (Co-Presenter/Co-Author), University of San Diego , tchristiansen@sandiego.edu;

Kate Boersma (Co-Presenter/Co-Author), University of San Diego , kateboersma@sandiego.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Effects of protection status and low-impact recreation on aquatic macroinvertebrate communities in the Niobrara River, Nebraska, USA North American prairie streams remain understudied despite their importance as model systems for disturbance ecology, their role as drivers of downstream water quality, and the biodiversity they harbor. Overlooking prairie streams puts them in danger of undocumented functional loss or change, thus necessitating the need for federal protection designation mandates of these systems in the USA. We investigated the effects of protection designation of prairie streams on macroinvertebrate diversity through integrative measures such as food web composition and multimetric diversity indices in a 26.4-km stretch of the federally protected, mid-sized Niobrara River, Nebraska, USA. We identified 4,900 macroinvertebrates belonging to 50 families and calculated a Hilsenhoff Biotic Index (HBI) of 4.49 and a Shannon Index of 1.94 across 15 sites and three months of sampling (June, July, and August). Further, [E]phemeroptera [P]lecotpera and [T]richoptera percent abundance ranged from 32.8% in June to 76.6% in August. Together, these indices suggest the water quality in the Niobrara River supports diverse macroinvertebrate assemblages containing sensitive taxa. We propose to extend this study into the unprotected, agricultural Elkhorn River (Nebraska, USA) based on differences in preliminary observations of functional feeding group dominance and primary productivity for comparative studies of the importance of protection designation. We anticipate that the invertebrate food webs for both systems will differ and propose that connecting functional feeding group abundance and food web metrics will provide empirical data in support of protection designation for macroinvertebrate diversity and associated ecosystem functions.

Rodrigo Meza Gonzalez (Primary Presenter/Author), University of Nebraska at Omaha , rigo.mez.glez@gmail.com;

Jennifer Dailey (Co-Presenter/Co-Author), University of Nebraska at Omaha/South Dakota DANR , jenniferdailey@unomaha.edu;

Paul Ayayee (Co-Presenter/Co-Author), University of Nebraska at Omaha , payayee@unomaha.edu;

Jessica Corman (Co-Presenter/Co-Author), University of Nebraska-Lincoln , jcorman3@unl.edu;

David Manning (Co-Presenter/Co-Author), University of Nebraska at Omaha , davidmanning@unomaha.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

DIFFERENCES IN ATTRACTION TO ARTIFICIAL LIGHT BETWEEN LARVAL AND ADULT STAGES OF MAYFLIES Aquatic emergent insects are an important resource subsidy, linking aquatic and terrestrial ecosystems. Aquatic habitats are susceptible to anthropogenic activities, including artificial light at night (ALAN), which may impact cross-system exchanges. ALAN research in freshwaters has focused on impacts to adult emergent insects; little is known, however, about the impacts of ALAN during larval phases. Here we investigate the mayfly family Caenidae to assess the potential impact of ALAN across larval and adult stages, and how they might respond differently to light spectra emitted by LEDs. We performed our replicated field study in the littoral zone of a pond at Seven Ponds Nature Center in Dryden, Michigan (U.S.A.). We installed 5 light treatments (3 replicates each) in the littoral zone of the pond: 3 narrow-band LEDs (410 nm, 530 nm, 630 nm), a broad-spectrum LED (4000k), and a dark control. We sampled over 4 nights throughout the summer of 2022 from floating pan traps to capture adults, and submerged activity traps to collect larvae. We found no difference in larval abundance among all LED treatments and dark controls (p=0.76). Adult Caenidae, however, were attracted to violet LEDs (410nm) compared to other treatments (p<0.01). Caenidae abundance differed among dates for both the adult and larval life stage (p=0.001, p=0.04, respectively). Together these results highlight how the effects of ALAN can vary during insect ontogeny and suggest that longer wavelengths of light emitted by LEDs will have the greatest impact to adult mayflies.

Melanie Bruno (Primary Presenter/Author), Oakland University , melaniebruno@oakland.edu;

Elizabeth Parkinson (Co-Presenter/Co-Author), Dept. Biological Sciences, Oakland University , emparkinson@oakland.edu;

Scott Tiegs (Co-Presenter/Co-Author), Oakland University , tiegs@oakland.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Species Diversity of Mayfly (Ephemeroptera) Nymphs in the Lower Ogeechee River Basin Mayflies are an important indicator group of insects due to their sensitivity to biotic and abiotic changes in freshwater systems. The Ogeechee River in Georgia is sparsely developed, making it an ideal candidate for mayflies to thrive. Species-level identification has never been officially conducted in the Ogeechee or the Georgia Coastal Plain. Field sampling was conducted to get a deeper understanding of the taxonomic diversity of the mayfly species that inhabit this river. Select specimens were reared in the lab to attempt controlled emergence, facilitating the identification of later stages of nymph development. Remaining specimens were stored in ethanol and identified in the lab using light microscopy. Taxonomic keys and a literature review allowed for identification to species level for select specimens. Previously collected samples from 2014 were included and identified to genus level for a community assessment of the river. Maccaffertium smithae was the most abundant species in our sampling and the supplemental 2014 samples. This species was previously unidentified in this part of Georgia. Defining characteristics including truncated gills, projections on abdominal terga 7-9, and coloration of abdominal sterna allowed us to identify the species as M. Smithae. The number of setae on the maxillary crown did not match the literature data; the count is more similar to that in M. modestum. This inconsistency raised questions about the authenticity of the literature since these species are commonly confused due to taxonomic similarities. This study identified the need for proper taxonomic revision on the species level for mayflies.

Thomas Pacious (Primary Presenter/Author), College of the Holy Cross , paciousthomas@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Relationship between the physicochemical parameters of Neotropical rivers and Veliidae populations. Aquatic macroinvertebrates are vulnerable to changes in the physicochemical parameters of water. Their sensitivity to pollution makes them excellent bioindicators of water quality and its degree of contamination. Veliidae is an aquatic macroinvertebrate found in most aquatic ecosystems in Puerto Rico. However, more studies are needed to understand the impact of physicochemical parameters on the populations of these aquatic invertebrates. The main objective of this study was to assess the presence of Veliidae in 10 rivers and streams in Puerto Rico. A total of 525 individuals were collected during the sampling. Correlations were reported between the abundance of these invertebrates and the concentrations of physicochemical parameters in the water. The study reported positive correlations between Veliidae populations and the physicochemical parameters: conductivity (EC), TDS (ppm), and salinity (ppt). Long-term studies are suggested during the rainy and dry seasons to evaluate temporal changes in water physicochemical parameters and their impact on Veliidae populations.

Christopher E Orozco González (Primary Presenter/Author), Ana G. Méndez University , corozco5@email.uagm.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

POPULATIONS OF A BURROWING CRAYFISH LIMITED BY HYDROPERIOD IN A SEASONAL WETLAND The Everglades crayfish, Procambarus alleni is a short-lived crayfish that lives in seasonal subtropical wetlands in Florida and is an important diet item for nesting wading birds. The hydroperiod limitations of the populations of P. alleni and the mechanism by which water depth variation produces high densities aboveground are not well understood. To look for patterns consistent with population limitation by hydrologic stress (short hydroperiods) we have been sampling crayfish and monitoring burrows in seasonal wetlands in southern Florida. Six marl prairie sites (1 ha each) were selected along a hydroperiod gradient with three shorter hydroperiod (2-4 mo.) sites and three longer hydroperiod (6-8 mo.) sites. Aboveground crayfish densities were quantified with replicated 1-m2 throw traps up to three seasons per year (2022-2024) whenever water depths exceeded 5 cm. Burrow densities were monitored on 50m2 belt transects at each sample site. Populations at all sites were juvenile dominated and reproduction was timed to re-flooding of the marsh surface (July or September). In the late wet season (October) all sites could be sampled at the same time. The three shorter hydroperiod sites with shallower water and less inundation time supported relatively higher densities of smaller crayfish and lower biomass (mean dry mass = 8.2 g/m2) than the longer hydroperiod sites (24.9 g/m2). Average densities of active burrows were 50% higher in the longer hydroperiod sites in the dry season. The biomass in the wet season and densities of burrowed crayfish both indicate that the populations are limited by hydroperiod shortening.

Christina Tilley (Primary Presenter/Author), Florida International University , ctilley@fiu.edu;

Nathan Dorn (Co-Presenter/Co-Author), Florida International University , ndorn@fiu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

LAND USE VITIATES THE ECOLOGICAL INTEGRITY OF LOW-ORDER STREAMS IN AFROMONTANE HEADWATER STREAMS Low-order streams contribute to the abiotic and biotic characters of large rivers and are renowned for harboring unique forms of aquatic flora and fauna. In the Afrotropics, land-use change in the catchments of headwater streams has replaced natural forests with croplands, grasslands and human settlements. Unfortunately, these ecosystems have historically been overlooked in environmental legislation and bioassessment programs. In this study, we investigated whether land-use, river network characteristics and associated physico-chemical parameters effectively predict variation in the structure and function of macroinvertebrate assemblages and the differences that occur between shaded first-order streams and unshaded second-order streams in the Nzoia River Basin, Kenya. Beyond measures of stream size (e.g. width, depth, discharge), first- and second-order streams differed significantly (p < 0.05) in stream water conductivity, dissolved oxygen, and course organic matter standing stocks. First-order streams had higher macroinvertebrate abundance than second-order streams. Taxa from the families Ephydridae, Elmidae, Gomphidae, and the genera Euthraulus, Neoperla, Orthothrichia and Prosopistoma were limited to the second-order streams, while Ceratopogonidae, Pisuliidae, Dytiscidae and Trichosetodes occurred only in first-order streams. Collector-filterers and collector-gatherers were the most abundant macroinvertebrate FFGs. As expected, shredders were most abundant in the first-order streams while scrapers were most abundant in our open-canopy second-order streams. The physical differences between the first- and second-order streams predicted changes in macroinvertebrates composition. This study suggests that the transition from allochthonous to autochthonous food webs, predicted to occur in mid-order reaches, is shifted upwards in Afrotropical watersheds where forests have been converted to other land uses.

Augustine Sitati (Primary Presenter/Author), University of Alabama , ansitati@crimosn.ua.edu;

Mourine Yegon (Co-Presenter/Co-Author), University of Natural Resources and Life Sciences (BOKU) , mourineyegon@gmail.com;

Steven Thomas (Co-Presenter/Co-Author), University of Alabama , sathomas16@ua.edu;

Frank Masese (Co-Presenter/Co-Author), University of Eldoret , f.masese@uoeld.ac.ke;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

RESPONSES OF BENTHIC MACROINVERTEBRATE COMMUNITIES TO PERTUBATIONS IN AN IMPACTED EAST TENNESSEE STREAM Understanding ecosystem dynamics requires observational datasets that match the temporal scale of environmental variation within a system. This is especially true in highly impacted systems that may experience a wide variety of natural and anthropogenic stressors that vary through time. East Fork Poplar Creek (EFPC) is a mercury-contaminated stream located on the US Department of Energy’s Oak Ridge Reservation, in east Tennessee, USA. Since 1985, the Biological Monitoring and Abatement Program (BMAP) at Oak Ridge National Laboratory has been evaluating the responses of the benthic macroinvertebrate community to various remediation actions taken to improve water quality in EFPC. Samples are collected biannually by Hess surveys at three sites along the creek. The nearly 40-year BMAP dataset provides a unique opportunity to explore how benthic macroinvertebrate communities in EFPC have responded to chronic and acute perturbations to the system, which have included significant alterations in flow and episodic releases of contaminants including mercury. Time series analyses of species abundance metrics at multiple sites along EFPC indicate that macroinvertebrate richness at the two upstream sites has been somewhat impacted by some of these perturbations, while richness at the downstream site has remained mostly unimpacted.

Nikki Jones (Primary Presenter/Author), Oak Ridge National Laboratory , jonesnj@ornl.gov;

Paul Matson (Co-Presenter/Co-Author), Oak Ridge National Laboratory , matsonpg@ornl.gov;

Natalie Griffiths (Co-Presenter/Co-Author), Oak Ridge National Laboratory , griffithsna@ornl.gov;

Teresa Mathews (Co-Presenter/Co-Author), Oak Ridge National Laboratory , mathewstj@ornl.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Spring Boxing Impacts on Rare, Threatened, and Endangered Macroinvertebrate Taxa and specialist communities Habitat fragmentation, pollution, and invasive species are reducing aquatic insect biodiversity globally while climate change threatens to disrupt the phenological cycles on which insects depend. Springs exist as "habitat islands," which play a crucial role as stable refugia for rare, threatened, and endangered (RTE) species in the face of global climate change. However, the impact of spring boxing and visitor use on macroinvertebrate communities remains poorly understood. In Shenandoah National Park (SNP), spring boxing is a historical practice to enhance water access, which alters the hydrology of these critical habitats. We sampled 63 sites of varying modification levels (unmodified, box, piped) across the park. Our study aims to evaluate the effects of spring modification on community composition by analyzing qualitative diversity samples and long-term temperature data. We anticipate finding: 1) greater species richness in open springs vs. closed, 2) increased species presence correlating with habitat characteristics, 3) a greater occurrence of RTE taxa in open springs, and 4) greater RTE taxa presence in springs associated with less visitor use. Shenandoah National Park prioritizes preservation, and understanding the biological and hydrological impacts of spring boxing and channelization is crucial for future restoration and conservation decisions. The park's sensitive habitats, containing rare and threatened species, necessitate effective management strategies. Detection of RTE species may prompt increased protection measures, such as mitigating runoff and sedimentation from trail erosion and visitor use. Understanding the impacts of spring modification is crucial for guiding future conservation decisions and maintaining SNP’s mission of biodiversity preservation.

Sydney Haney (Primary Presenter/Author), Virginia Tech , srhaney@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

The relative contributions of phylogeny and environment on stoichiometric variation in odonate larva Body stoichiometry, the balance of elements within an organism, is linked to ecosystem functioning through variation among and within species in acquisition, assimilation, allocation, and excretion of elements. Variation in the elemental composition of organisms can be explained by both ecological and evolutionary drivers. Environmental factors like temperature, nutrient cycling, trophic status, and species introductions can alter stoichiometric composition of organisms. While much research has focused on ecological drivers, little research has addressed the contribution of phylogenetic relatedness to body stoichiometry in natural communities. Phylogenetic relationship may also explain some of the stoichiometric variation among taxa. Traits in closely related taxa arise from similar evolutionary histories that likely have similar stoichiometric demands. Here, we report on how both the environment and phylogeny contribute to stoichiometric variation in larval odonates of Medicine Bow National Forest (Wyoming, USA). We collected 742 odonate individuals from 6 families and 10 genera from 31 lakes, ponds, and rivers over 3 months (July – September 2023). Sample sites ranged between 2183m and 3264m elevation. At every site, we collected periphyton to assess primary production and measured temperature, DO, conductivity, and elevation. For every individual, we measured the length and weight, assessed the instar stage, and identified to the genus level. All individuals are being analyzed for %C, % N, and %P content in the University of Wyoming Stable Isotope Facility. We predict differences in body stoichiometry between waterbody type (beaver pond, lake, stocked, native fish, or fishless), temperature, elevation, trophic status, and phylogenetic relatedness.

Spencer Cruz (Primary Presenter/Author), University of Wyoming , scruz6@uwyo.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

A conceptual framework for sediment metabolism in intermittent rivers during dry-to-flow transitions Intermittent rivers and ephemeral streams (IRES) are dominant in the global fluvial network, characterized by drying and flow resumption cycles. Gaps remain in understanding how the specific transitioning characteristics from dry to flow (i.e. flow resumption) shape sediment biogeochemical responses in IRES. During this transition, dry sediments can either directly experience flow or first become moist or inundated (stagnant water) before reaching surface flow. We propose a conceptual framework that defines three stages: moist (no flow and unsaturated), inundation (100% saturated, maybe water column), and flow (surface advective flow). Additionally, the flow phase can be characterized by different flow velocities. We propose that the duration of those stages and the characteristics of flow will affect the biogeochemical responses upon flow resumption. To partially test our conceptual framework, we conducted experiments using gas-tight cylindrical flumes (50 L) simulating flow conditions in dry IRES sediments and measuring CO2 fluxes. The experimental setup involved either an instant flow resumption event (no moist or inundation stage, flow directly) or a 6-hour inundation (slow resumption including a moist and inundation stage), each followed by a full day underflow at different velocities. CO2 flux was comparable for all velocities in each treatment (instant and slow). Interestingly, the peak of CO2 production after flow occurred after 15h for instant flow resumption, while at 9h for slow (15h after inundation started). Based on our findings, the different duration of stages of flow resumption appear to strongly influence the stream CO2 fluxes rather than the characteristics of the flow.

Jose Schreckinger (Co-Presenter/Co-Author), RPTU, iES , j.schreckinger@rptu.de;

Ute Risse-Buhl (Co-Presenter/Co-Author), RPTU, Ecology Department , ute.risse-buhl@rhrk.uni-kl.de;

Maria Isabel Arce (Co-Presenter/Co-Author), Department of Ecology and Hydrology, University of Murcia , marisarce@um.es;

Clara Mendoza Lera (Primary Presenter/Author,Co-Presenter/Co-Author), RPTU, iES , clara.mendozalera@rptu.de;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Contrasting roles of discharge in shaping headwater stream CO2 regimes Headwater streams are increasingly recognized as hotspots for CO2 evasion. However, relatively little is known regarding how much and why stream CO2 concentration varies through time and across biomes. One approach to understanding temporal patterns in stream CO2 is to examine relationships between concentration and discharge, as discharge regulates carbon delivery from the landscape, in-stream transformations, and subsequent evasion and export. We examined CO2 concentration-discharge relationships across biomes throughout the National Ecological Observatory Network from 2021 to present in grassland (KING), boreal (CARI), mountain (COMO), temperate forest (WALK), and temperate rainforest (MART) streams. Initial results suggest distinct annual patterns in CO2 concentration among sites, with discharge playing contrasting roles in shaping the CO2 regime. For example, we observed dilution of CO2 during higher flows at KING and MART, enrichment during higher flows at CARI and WALK, and under-ice buildup and emission during freshet at COMO. We also observed large diel CO2 variation during warm, low flow summer months, suggesting that flow and temperature may act as universal regulators of in-stream transformations of C. Ongoing analyses of paired O2 and CO2 departures from saturation, estimation of in-stream metabolism, and finer temporal scale patterns will be integrated to test the mechanisms underlying observed patterns.

Frances Iannucci (Primary Presenter/Author), Virginia Tech , frances.m.iannucci@gmail.com;

Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , ehotchkiss@vt.edu;

David Butman (Co-Presenter/Co-Author), University of Washington , dbutman@uw.edu;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire , wil.wollheim@unh.edu;

Jeremy B. Jones (Co-Presenter/Co-Author), University of Alaska Fairbanks , jbjonesjr@alaska.edu;

Keli Goodman (Co-Presenter/Co-Author), National Ecological Observatory Network (NEON) operated by Battelle , kgoodman@battelleecology.org;

Kaelin Cawley (Co-Presenter/Co-Author), National Ecological Observatory Network (NEON) operated by Battelle , kcawley@battelleecology.org;

Robert Hensley (Co-Presenter/Co-Author), National Ecological Observatory Network (NEON) operated by Battelle , hensley@battelleecology.org;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Assessing the Role of Phytoplankton on the Biogeochemistry in Geographically Isolated Wetlands Phytoplankton serve vital roles as bioindicators for freshwater ecosystems' health and energetics. Nonetheless, there is a lack of research on phytoplankton and their role in carbon cycling in geographically isolated wetlands (GIWs), ecosystems with substantial contributions to landscape-scale carbon fluxes. To evaluate the role of phytoplankton in these ecosystems’ carbon metabolism, we studied three GIWs of varying depths and hydrological regimes located on the Delmarva peninsula in the US mid-Atlantic. In 2023, we measured dissolved oxygen (DO) using high-frequency sensors and sampled surface water chlorophyll a concentration as a proxy for phytoplankton abundance. Samples were taken quarterly, capturing wetland drawdown and rewetting periods. We also quantified primary productivity in the least-hydrologically variable site using light/dark bottle experiments in mid-July and late September. We found that chlorophyll a at our most-hydrologically variable site was consistently low (<5 ug/L). Our semi- and least-hydrologically variable sites, however, had chlorophyll a averages of 13 ug/L (range: 2-47 ug/L) and 19 ug/L (range: 0-64 ug/L), respectively. Incubations revealed that our least-hydrologically variable site has a GPP:ER > 1 (chlorophyll a: ~10 ug/L), indicating that GIW water columns can be autotrophic. Ongoing work integrates the metabolism estimates from the incubations with the DO daily fluxes at this site (ranged from 2.4-8.5mg/L over the incubation days). This data establishes a relationship between phytoplankton and the ecosystem’s overall metabolism, which contributes to the understanding of GIWs’ greenhouse gas dynamics. Future steps include comparing metabolism data to different types of wetlands and identifying phytoplankton population dynamics throughout the year.

Emily Mulcahy (Primary Presenter/Author), Virginia Polytechnic Institute and State University (Virginia Tech) , mulcahyemily1@gmail.com;

Carla López Lloreda (Co-Presenter/Co-Author), Virginia Tech , carlalopez@vt.edu;

Katherine Wardinski (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , wardinskik@vt.email;

Nicholas Corline (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , njcorline@vt.edu;

Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , ehotchkiss@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Consequences of freshwater salinization on stream carbon cycling Salinization is an increasingly prevalent stressor across freshwater ecosystems yet its influence on ecosystem metabolism and carbon cycling needs to be better understood. Mining practices in the Appalachian region of the U.S. have led to the deposition of salts (notably Ca2+ and SO42) into the region's headwaters. Eastland Creek, a reference stream with a measured specific conductivity of 25 µS/cm, and Rickey Branch, a high salinity stream with a measured specific conductivity of 1457 µS/cm, were sampled from February 2021 to August 2022 to collect preliminary metabolism estimates for comparison between high/low salinity sites. Metabolism measurements were derived from temperature, oxygen, and discharge data using streamMetabolizer in R. Mean oxygen saturation was similar across both sites: 10.6% and 10.7% at Rickey Branch and Eastland Creek respectively. Preliminary metabolism results indicate increased heterotrophy (ER > GPP) in high-salinity streams relative to one low-salinity reference. We are expanding the project to include oxygen and light measurements from nine streams across the Appalachian coal-mining region to test how ecosystem metabolism varies across a conductivity gradient, with Eastland & Rickey representing lowest and highest salinity among all sites. Metabolism estimates from these sites will be used to distinguish how varying salinization levels across stream networks will influence temporal patterns in carbon cycling and basal resource production. We anticipate an increase in heterotrophy with salinity in these streams. Understanding how varying salinity levels influence ecosystem metabolism is essential to help preserve ecosystem health as freshwater salinization becomes more prevalent across inland waters.

Caleigh Meehan (Primary Presenter/Author), Virginia Tech , cemeehan@vt.edu;

Daniel McLaughlin (Co-Presenter/Co-Author), Virginia Tech , mclaugd@vt.edu;

Sally Entrekin (Co-Presenter/Co-Author), Virginia Tech , sallye@vt.edu;

Stephen Schoenholtz (Co-Presenter/Co-Author), Virginia Tech , schoenhs@vt.edu;

Kelley Sinning (Co-Presenter/Co-Author), Virginia Tech , kelley.sinning@gmail.com;

Lisa Tabor (Co-Presenter/Co-Author), Virginia Tech , lmt@vt.edu;

Teresa Brown (Co-Presenter/Co-Author), University of Virginia's College at Wise , tlb9fd@uvawise.edu;

Carl Zipper (Co-Presenter/Co-Author), Virginia Tech , czip@vt.edu;

Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , ehotchkiss@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

USING NUTRIENT DIFFUSING SUBSTRATA (NDS) TO EXPLORE NUTRIENT LIMITATIONS IN A MANAGED FORESTED WATERSHED IN ALABAMA Autotrophic biofilms (e.g., algae and diatoms) serve multiple important functions in headwater stream ecosystems, driving rates of carbon fixation and serving as an important energy source. However, algal growth is often limited by the availability of dissolved nutrients, especially inorganic forms of [N]itrogen (as nitrate, NO3- or ammonium, NH4+) and [P]hosphorus (as phosphate, PO43-). We conducted repeated deployments (June, July, and September) of nutrient diffusing substrata (NDS) to explore the factors controlling algal growth in Coastal Plain streams. We placed NDS across nine sites nested within the South Sandy Watershed (125 km2), which flows within the Talladega National Forest in central AL. For each NDS deployment, we included the following treatments: control (no nutrients added), +N, +P, and +N+P, with 5 NDS per treatment deployed at each site. We topped each NDS with an inorganic fritted glass disk to promote autotrophic biofilm growth. We left the NDS to incubate for 3-4 weeks during each deployment. After each incubation, we estimated the response of algal growth to each nutrient treatment via chlorophyll-a (chl-a) concentrations. In June, we found no difference in chl-a across nutrient treatments at all sites, indicating that algal growth experienced little nutrient limitation. However, we then observed significant nutrient limitation in July, especially N and N+P limitation. Our results suggest strong seasonal controls on biofilm growth and function across the South Sandy watershed. Capturing the nutrient limitation status of biofilms reveals the dynamic drivers of primary productivity in headwater stream ecosystems.

Sarah Kelley (Primary Presenter/Author), The University of Alabama , sgkelley1@gmail.com;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

Savannah Hansen (Co-Presenter/Co-Author), The University of Georgia , savannah.hansen@uga.edu;

Jacob Dorris (Co-Presenter/Co-Author), The University of Alabama , jddorris@crimson.ua.edu;

Zacharie Loveless (Co-Presenter/Co-Author), The Unversity of Alabama , ztloveless@crimson.ua.edu;

Carla L. Atkinson (Co-Presenter/Co-Author), University of Alabama , clatkinson@ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

In the boreal forest net carbon exchange puzzle, how big of a piece are stream CO2 emissions? Streams and rivers are usually sources of CO2 to the atmosphere. Quantifying the CO2 emitted from headwater streams and understanding the drivers is important to accurately account for all of the fluxes of dissolved inorganic carbon (DIC) out of the stream ecosystem in order to estimate net ecosystem exchange (NEE). This study focuses on an interior Alaskan boreal forest ecosystem where the effects of climate change are resulting in permafrost thaw and destabilization of permafrost carbon. We used high-frequency sensor measurements of stream water O2 to model gas exchange (K) estimates across three years. Using concomitant measurements of CO2, we estimated CO2 evasion from the stream. We aligned stream gas exchange calculations with the National Ecological Observatory Network’s (NEON) eddy covariance CO2 measurements to determine the contribution of the stream (CARI) to the terrestrial net carbon exchange (BONA). Preliminary results indicate that our stream site has higher and more variable pCO2 later in the summer months as the permafrost active layer thaws, potentially signaling inputs from deeper terrestrial flow paths and increased in-stream microbial activity. Further, we found no strong relationship between gas exchange and discharge, indicating that stream flow may not have a large impact on stream CO2 emissions. We expect that as permafrost thaw progresses and the growing season lengthens, boreal streams will be fed by increasingly deep groundwater sources with higher DIC concentrations than shallow, organic-rich sources. This shift in terrestrial flow path may lead to streams becoming stronger sources of CO2 and greater contributors to NEE.

Kristin Olson (Primary Presenter/Author), University of Alaska Fairbanks , kolson39@alaska.edu;

Jeremy B. Jones (Co-Presenter/Co-Author), University of Alaska Fairbanks , jbjonesjr@alaska.edu;

Erin Hotchkiss (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University (Virginia Tech) , ehotchkiss@vt.edu;

David Butman (Co-Presenter/Co-Author), University of Washington , dbutman@uw.edu;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire , wil.wollheim@unh.edu;

Keli Goodman (Co-Presenter/Co-Author), National Ecological Observatory Network (NEON) operated by Battelle , kgoodman@battelleecology.org;

Kaelin Cawley (Co-Presenter/Co-Author), National Ecological Observatory Network (NEON) operated by Battelle , kcawley@battelleecology.org;

Frances Iannucci (Co-Presenter/Co-Author), Virginia Tech , frances.m.iannucci@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

EFFECTS OF MULTIPLE STRESSORS ON ALGAL BIOFILM GROWTH: MANIPULATING SEDIMENT DEPOSITION AND UREA NITROGEN CONCENTRATIONS Agricultural activities can put an exorbitant amount of stress on freshwater ecosystems through land use change, increased erosion, runoff, and excess nutrients or contaminants from fertilizers and pesticides. The fertilizers and pesticides used for agriculture are often changing as seen with the recent increased use of urea-based fertilizers. The effects of urea-based fertilizers on freshwater ecosystems are less well studied than the effects of nitrates and ammonium. Urea is an organic source of nitrogen, unlike ammonium and nitrates, and has been shown to have the potential to increase the toxicity of cyanobacteria as well as impacting algal community structure. To test the effects of agricultural stressors on stream ecosystems we utilized a flow-through mesocosm experiment with 30 streams and a gradient design with 5 sediment (0-30 g/L) and 5 urea treatments (0-240 µg/L). We measured algal growth over 22 days (August-September 2023) through chlorophyll a and ash free dry mass and community composition using a BenthoTorch. The community was originally dominated by diatoms and moved toward cyanobacteria throughout the duration of the experiment. Preliminary results indicate that the lowest urea treatment (30 ug/L) combined with the minimal sediment treatment (0-7 g/L) yielded the greatest algal biofilm growth as ash-free dry mass. This study shows how multiple stressors in stream ecosystems can interact to affect the functioning of the ecosystem. Particularly, excess sediment can inhibit the capacity of algae to take up nitrogen fertilizers, which can exacerbate nutrient loading in sensitive downstream ecosystems.

Claire Ebner (Primary Presenter/Author), Kent State University , cebner3@kent.edu;

Renn Schipper (Co-Presenter/Co-Author), Kent State University , rschipp1@kent.edu;

Olufemi Akinnifesi (Co-Presenter/Co-Author), Kent State University , oakinnif@kent.edu;

Talia Pope (Co-Presenter/Co-Author), Kent State University , tpope8@kent.edu;

David Costello (Co-Presenter/Co-Author), Kent State University , dcostel3@kent.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

NUTRIENT STOICHIOMETRY AND DISSOLVED ORGANIC MATTER IN THE LOWER OHIO RIVER The Ohio River, a source of drinking water for roughly 4 million people, receives nutrients and organic matter from a large and diverse watershed. Cyanobacterial blooms occur each summer, at times resulting in dangerous toxin concentrations, as happened during the 2015 and 2019 blooms of Microcystis. We present historical data and new data for three sites on the Ohio River located throughout a 50-river-mile stretch from Cannelton, IN to Evansville, IN. For each site, we collected nutrient and other data 7 times during the 2023 water year. We use nitrogen (N), phosphorus (P), and dissolved silica (SiO2, DSi), concentrations to assess the extent to which stoichiometric conditions in the river favored diatoms over non-siliceous algae and cyanobacteria. For most of the year, DSi:N:P ratios indicated abundant DSi relative to N and P, suggesting stoichiometric conditions favored diatoms. However, in August the ratios dropped sharply (DSi:N to <1 and DSi:P to <16), likely as a result of diatom uptake of DSi. The diatom bloom shifted stoichiometric conditions to a state that favored cyanobacteria. Additionally, we examined the quantity and quality of dissolved organic carbon (DOC) to assess the contribution of autotrophic sources to the riverine DOM pool. DOC ranged from < 1 to 3.5 mg/L with increases in DOC concentration during high flow in December 2022 and during the height of the growing season during the late summer of 2023. This study supports our emerging hypothesis that DOM is coupled to DSi through phytoplankton composition and production.

Lindsey Rasnake (Primary Presenter/Author), Indiana University Bloomington , lrasnake@iu.edu;

Todd Royer (Co-Presenter/Co-Author), Indiana University , troyer@iu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

A Vast And Developing Phosphorus Sink In Thawing Arctic Soils Rising atmospheric temperatures in the Arctic region are driving widespread ecological change through thaw of previously frozen soil (permafrost). Permafrost thaw alters landscape hydrology, increases weathering rates, and thus increases the delivery of solutes to adjacent waters. Long-term monitoring of the Kuparuk River (North Slope, Alaska) has confirmed significant increases in many solutes that are indicative of thawing permafrost. However, contrary to our expectations, we found no evidence of an increase in phosphorus (P), the nutrient that most often limits primary production in tundra streams. Here, we show that soils in the upper Kuparuk River watershed have a high biogeochemical sorption capacity that can limit P mobility and use published data to show that this may be a pan-Arctic characteristic. The prevailing assumption is that P bioavailability is primarily restricted by vegetative cycling, but we found that concentrations of Mehlich-3 extractable iron (Fe) and aluminum (Al) impart a very high P sorption capacity across our study sites. Analysis of a pan-Arctic soils database suggests that this high P sorption capacity could be a ubiquitous feature of Arctic soils. Therefore, we conclude that while warming-induced permafrost thaw may increase P mobility, simultaneous increases in pedogenic secondary Fe/Al minerals will likely be sufficient to perpetuate landscape P retention in tundra soils and will continue to limit biological productivity in adjacent aquatic systems. The projection we present provides new information about landscape P movement and sequestration and potentially alters our understanding of how Arctic headwaters may respond to continued warming and permafrost degradation.

Frederick Sutor (Primary Presenter/Author), University of Vermont , fsutor@uvm.edu;

William Breck Bowden (Co-Presenter/Co-Author), University of Vermont , breck.bowden@uvm.edu;

Eric Roy (Co-Presenter/Co-Author), University of Vermont , Eric.Roy@uvm.edu;

Andrew Schroth (Co-Presenter/Co-Author), University of Vermont , aschroth@uvm.edu;

Alexander Michaud (Co-Presenter/Co-Author), Ohio State University , a.b.michaud@gmail.com;

David Emerson (Co-Presenter/Co-Author), Bigelow Laboratory for Ocean Sciences , demerson@bigelow.org;

Elizabeth Herndon (Co-Presenter/Co-Author), Oak Ridge National Laboratory , herndonem@ornl.gov;

Lauren Kinsman-Costello (Co-Presenter/Co-Author), Kent State University , lkinsman@kent.edu;

Stephanie Hurley (Co-Presenter/Co-Author), University of Vermont , stephanie.hurley@uvm.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Riparian rain: hydrology and bromide retention in soil along a tallgrass prairie stream terrestrial-aquatic interface Riparian zones are an important interface because they act as buffers that can stop or slow pollutants entering the water system. Riparian soils can absorb much of the pollutant-rich runoff, but little is known about this function in native tallgrass prairie. We did four field experimental simulations of rain falling on riparian zones by running sprinklers attached to a reservoir of deionized water labeled with bromide near streams to assess the movement of the water into the soil and the bromide that was retained in soil. Our experimental additions occurred along a strip 12 m long perpendicular to the stream channel and 3 m wide. We tested responses on vegetated and bare areas with different slopes. These experiments simulated a strong thunderstorm with 5 –15 cm of water falling over 31 to 54 minutes. We found little influence on total soil moisture, but that bromide entered soil in three of four experiments down to 12.5 cm depth, and soil concentrations decreased with depth. Velocity of movement into the soil was roughly 0.6 cm/min. The experiment where bromide and water did not enter the soil was heavily trampled by bison, so soil was compacted and there was little vegetation to impede runoff. Follow-up sampling weeks after the experiment indicated subsequent storms washed the bromide down through the soil. These experiments allowed us to specifically measure riparian retention immediately next to a native tallgrass prairie stream.

Brooke Burris (Primary Presenter/Author), Kansas State University , blburris@ksu.edu;

Abu Raihan (Co-Presenter/Co-Author), Kansas State University , aburaihan@ksu.edu;

Walter Dodds (Co-Presenter/Co-Author), Kansas State University , wkdodds@ksu.edu;

Madison Moriello (Co-Presenter/Co-Author), Kansas State University , moriello@ksu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

BIOAVAILABILITY OF DISSOLVED ORGANIC CARBON WITHIN EIGHT URBANIZED WATERSHEDS ACROSS THE PORTLAND, OR, METROPOLITAN AREA (OREGON, USA) Bacterial utilization of dissolved organic carbon (DOC) is dependent on DOC molecular composition and size, which are likely to be altered substantially as urbanization affects the sources, transport, and transformation of DOC This study looks at the bioavailable DOC (BDOC) concentrations across twenty sites from eight watersheds across an urbanization gradient within the Portland, OR, metropolitan area. We hypothesized that BDOC would decrease in the fall compared to summer due to increased water turbidity and decreased sun exposure and temperature. Triplicate surface water samples were collected in July 2023 and again in October 2023 to measure seasonal effects. The samples were filtered, inoculated with pooled unfiltered water, and incubated for 28 days in the dark at 20°C. Significant differences in %BDOC between summer and fall were found, with averages ranging from ~15% to ~60% net DOC loss in the summer and a range of ~10% to ~35% loss observed in the fall. Seasonal differences were seen in the Clackamas watershed samples, with a greater loss of DOC in the summer versus fall (~40% and ~25% respectively), and in Lake Oswego, with ~30% and ~15% loss, respectively. The Tualatin watershed showed the least change between the seasons, with ~17% BDOC loss in the summer and ~18% in the fall. Different environments and urban inputs within these different watersheds significantly alter DOC bioavailability. Continued sampling in the winter and spring will be used to gain further insight into the effects of seasonality and urbanization on BDOC.

Mary Munt (Primary Presenter/Author), Portland State University , munt@pdx.edu;

Jacob Rudolph (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , rudolphjc@icloud.com;

Jennifer Morse (Co-Presenter/Co-Author), Portland State University , jlmorse@pdx.edu;

Rebecca Hale (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , haler@si.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

LONGITUDINAL DIFFERENCES IN NUTRIENT ACQUISITION AND ENZYMATIC ACTIVITY IN AN URBAN STREAM IN PORTLAND, OREGON Microbial metabolism in stream ecosystems plays an important role in carbon (C), nitrogen (N), and phosphorus (P) cycling and is an integral part of stream food webs. Urbanized watersheds remain relatively understudied despite the potential for altered C:N:P ratios and microbial metabolism due to significant changes in stream structure and surrounding land characteristics. Our study assessed the effects of urbanization on potential metabolic activity in streams by comparing rates of extracellular enzyme activity (EEA) and calculating C:N:P stoichiometric ratios from weekly samples of three sites along Johnson Creek in the Portland, Oregon, metropolitan area. Assays were run for dissolved organic matter (DOM), fluorescence, and rates of beta-glucosidase (BG), phosphatase (AP), leucine aminopeptidase (LAP), and phenol oxidase (POX) activity. We hypothesized that EEA rates would differ between the more and less urbanized sites because water-column C:N:P stoichiometry was found to differ along the urbanization gradient. Through stoichiometric vector analysis, and supported by fluorescence and nutrient data, we determined that the most urban site had the most labile C and highest levels of N. Despite differences in C:N:P stoichiometry, EEA rates remained relatively constant between sites. BG:LAP was consistently low, which suggests that microbial communities are using protein-rich DOM as a primary source of C rather than N. Although contrary to established enzymatic stoichiometric theory, the relative activities of C-, N-, and P-acquiring enzymes are consistent with findings from other cities, lending support to generalizable models of microbial nutrient acquisition in urban streams.

Zoie Brauser (Primary Presenter/Author), Portland State University , zbrauser@pdx.edu;

Jacob Rudolph (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , rudolphjc@icloud.com;

Jennifer Morse (Co-Presenter/Co-Author), Portland State University , jlmorse@pdx.edu;

Jennifer Follstad Shah (Co-Presenter/Co-Author), University of Utah , jennifer.shah@envst.utah.edu;

Kristina Hopkins (Co-Presenter/Co-Author), U.S. Geological Survey , khopkins@usgs.gov;

Rebecca Hale (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , haler@si.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

RACIAL DISPARITIES DURING 2016 FLOOD EVENTS IN LOUISIANA INSIDE AND OUTSIDE FEMA-FLOODPLAIN The frequency and intensity of floods are expected to increase in the state of Louisiana in the near future, due to climate-induced increases in heavy rainstorms and the naturally flat terrain and impermeable soils characteristic of the region. The US Federal Emergency Management Agency (FEMA) illustrates the risk of flooding through its 100-year flood zone map. However, recent flood events have occurred outside of this risk zone, limiting the capacity of residents to determine their potential impact. A recent study in the aftermath of Hurricane Harvey found that the proportion of areas outside the FEMA flood zone that were flooded was in fact higher for minority communities in terms of race, highlighting a potential social disparity in federal assistance in the face of a flood emergency. Our study seeks to investigate if a similar trend could be observed for the 2016 flood events in Louisiana, by determining if social factors associated with race, gender, or income were predictive of the proportion of people inside or outside the FEMA flood zone at two different geographical units (parcels and block groups). This study will help consider social equity in developing local policies for flood mitigation and highlight the importance of improving flood hazard risk mapping.

Israt Jahan Tama (Primary Presenter/Author), Louisiana State University , itama1@lsu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Spatio-temporal projections of precipitation in the Mekong River Basin based on a Regional Climate Model The Mekong River Basin (MRB) accommodates an approximate population of 70 million people, with precipitation serving as the primary water resource, exerting pronounced influence on ecological, productive, and livelihood aspects within the region. This study utilized the Regional Climate Model (RegCM), driven by CNRM-ESM2-1, to project forthcoming precipitation patterns in the MRB. The Quantile Mapping (QM) bias correction technique was applied to rectify simulated precipitation biases during both the baseline and future periods (2070-2099) under SSP245 and SSP585. Independent validation corroborated the efficacy of the QM technique in significantly mitigating biases and enhancing the fidelity of precipitation indices representation. Both projected future scenarios indicated an upward trajectory in MRB precipitation, with annual anomalies of 96 mm to 137 mm for the period 2070-2099. Marginal increments in precipitation during spring and winter were observed in the northern MRB, while the southern MRB experienced declines. Conversely, substantial and widespread increases in precipitation occurred during summer and autumn, hinting at a potential escalation in the frequency of droughts and heavy rainfall events. Daily rainfall under SSP585 from 2070 to 2099 exhibited a notable 5-10% augmentation in days with precipitation surpassing 20 mm/day. Spatially, regions with annual precipitation exceeding 2400 mm and 1800 mm expanded outward, particularly on the west side of the Annamite range, while the central region with annual precipitation exceeding 1500 mm shifted westward. These findings underscore substantial alterations in precipitation patterns, holding implications for forthcoming hydrological and climatic conditions within the MRB.

LONG TRINH-TUAN (Primary Presenter/Author), VNU Hanoi University of Science , trinhtuanlong@hus.edu.vn;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

IMPACTS OF CLIMATE CHANGE ON SEDIMENT AND NUTRIENT DYNAMICS ON CATCHMENT SCALE LEVEL: A CASE STUDTY ON THE LARGEST TRIBUTARY OF TONLE SAP LAKE The water quality of the Tonle Sap Lake is becoming a public concern due to urbanization and agricultural expansion. Hence, the SWAT model was employed to assess the spatial and temporal differences in sediment and nutrient loads. At the same time, the climate change scenarios were applied to evaluate changes in water quality at the Sen River basin, the largest tributary of Tonle Sap Lake. Results illustrated that the highest peak of monthly sediment and nitrate loading appeared in September and October, while the lowest was observed in April. The annual simulation result of the climate scenarios RCP 6.0 in the 2030s is predicted to increase for GFDL-CM3 and to decrease for GISS-E2-R-CC as compared with the baseline. In the 2060s, it will be twice as compared to the 2030s. This double change also occurred from RCP 6.0 to RPC 8.5. The IPSL-CM5-MR is predicted to increase for sediment but decrease for nutrients in RCP 6.0. Nutrient loads (in extreme change scenario) were most likely growing compared with baseline. This study investigated nutrient yields in the Tonle Sap Lake basin for the first time, which can further be generalized for the entire basin.

Sovatey Lim (Primary Presenter/Author), Open Development Cambodia Organization , sovateylim@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Hot Water Generation with Auxiliary by Heat Pump A Feasibility Study This study investigates the feasibility of a combined solar collector and heat pump system for sustainable and efficient hot water generation. A flat-plate solar collector design with a single glass pane, copper tubes, and a blackened absorber plate was tested. Experiments utilized two collector sizes (4m² and 6m²) with varying water flow rates (15L/min, 17.5L/min, and 20L/min) through a 200L storage tank. Solar collector efficiency reached 56.7%, heating water from 30°C to 80°C under diverse solar radiation conditions (505.2W/m² - 1,392.3W/m²). A 3,300W heat pump with a 25-plate heat exchanger and a 370W water pump were employed. Experiments identified 17.5L/min as the optimal flow rate, achieving 5.13% heat pump efficiency and heating water to 50°C in 22 minutes. The electricity cost for heating water from 30°C to 50°C at 17.5L/min was 1,382.48LAK, lower than other flow rates. The system can generate hot water up to 50°C with a maximum storage capacity of 800L. Economic analysis compared the combined system to a conventional coil water heater system. While the initial cost was higher (15,234,500LAK vs. 9,566,000LAK), it offered significant energy savings (81.36% annually) with a 5-year payback period and a 31.83% Internal Rate of Return (IRR). This study demonstrates the feasibility of the combined system for hot water generation. Despite the higher upfront cost, it offers substantial energy savings and a fast payback period, making it a viable option for sustainable and efficient hot water production.

xayalak vilaida (Primary Presenter/Author), National University of Laos , x.vilaida@nuol.edu.la;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Changes in periphyton biochemical properties across different winter intensities and road salt regimes Winter road salt application is increasing across the US for several reasons. An increase in the severity and frequency of winter storms is a major contributing factor to this increase. As the effects of climate change become more apparent, northern regions are predicted to experience more major snow events, requiring the use of more road salt to maintain safe driving conditions. Increases in the salinity of freshwater habitats has negative consequences for the organisms there. A previous survey (2018-2019) of periphyton responses to winter road salt use showed an increase in omega-6 fatty acid molecules correlated with high salinity measurements. We recently replicated this survey in the latter half of 2023. The 2023 early winter season was much more mild in comparison to 2018, with warmer air temperatures and less consistent snowfall. Despite a colder (average air temperature 0.67 °C) and snowier (measured stream salinity 0.524 ppt) Dec 2018, Dec 2023 was warmer (average air temperature 4.11 °C) but had one large snow event (measured stream salinity of 0.564 ppt). We will examine how periphyton biomass (chlorophyll and AFDM), nutrient stoichiometry (phosphorous), and fatty acid composition (omega-3:omega-6) have changed between very different winter seasons. We hypothesize that while biomass may be negatively affected due to increases in precipitation run-off, fatty acid profiles and nutrient stoichiometry will reflect minimal impacts of salinity.

Sage Sellers (Primary Presenter/Author), Daemen University , sage.sellers@daemen.edu;

Sarah Whorley (Co-Presenter/Co-Author), Daemen University , swhorley@daemen.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Carbon dioxide, methane, and nitrous oxide fluxes from managed distributaries across the Rio Grande River Delta Aquatic ecosystems are globally important emitters of greenhouse gases (GHG), with small and human-made systems exhibiting a disproportionally high contribution to emissions compared to their global coverage. The Rio Grande Delta region along the US-Mexico border harbors a unique system of abandoned channels, distributaries, and their associated ox-bows—locally known as ‘resacas’—that serve as sources of biodiversity refuge, human recreation, flood control, and irrigation. Formed by the Rio Grande’s natural flooding cycles over the past 10,000 years, resacas are now artificially sustained due human alterations in the river’s flood cycles by dams, levees, and diversion systems. Patterns of GHG emissions from these uniquely managed natural aquatic ecosystems remain largely unexplored. To understand spatial, temporal, and hydrological influences on GHG emissions, we focus on biweekly sampling across three distinct resacas, each managed under different hydrologic regimes. We use portable GHG analyzers to quantify diffusive fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as ebullitive fluxes of greenhouse gases, particularly CH4. In addition, we quantify basic limnological parameters such as dissolved oxygen, chlorophyll-a, temperature, pH, turbidity, and conductivity using a portable water quality probe. We hypothesize that temperature, seasonality, and hydroperiod significantly influence the GHG fluxes from these systems. Indeed, our initial findings suggest warmer conditions and extended water residence times are associated with increased emissions of CO2, CH4, and N2O. This research offers novel insight into the GHG dynamics of the Rio Grande Delta and their potential responses to future hydrological and temperature changes.

Siena Stassi (Primary Presenter/Author), University of Texas- Rio Grande Valley , siena.stassi01@utrgv.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

WATER SOURCE AFFECTS ABUNDANCE, DIVERSITY AND TEMPORAL STABILITY OF MACROINVERTEBRATE COMMUNITIES IN THE TROPICAL HIGH ANDES High-elevation streams have heterogeneous water sources that can strongly impact biodiversity patterns. In the tropical Andes, there are two major water sources: glacier runoff and groundwater springs. Glacier-fed streams have flashy, unpredictable flows, while groundwater-fed streams are highly stable and predictable. We collected macroinvertebrates from paired groundwater and glacier-fed streams through a full year and asked the following two questions: 1) do the stable groundwater-fed streams have greater macroinvertebrate richness and abundance? 2) is macroinvertebrate community structure more stable through time in the groundwater-fed than glacier-fed streams? We collected data using a Surber sampler from five pairs of glacier/groundwater streams on the volcanoes Cotopaxi and Chimborazo. Each pair shared a common watershed and converged downstream of our sample locations. Data collection spanned nine evenly distributed dates from October 2014 through August 2015. Sorting and taxonomic identification are ongoing. When complete, we will run paired t-tests to answer question 1 and use the Bray-Curtis similarity index to answer question 2. Preliminary data from one stream pair with all nine sample dates complete suggest groundwater streams have greater richness and abundance than glacier-fed streams, as well as greater stability of community structure through time. If groundwater sources persist through climate change, they might serve as refuge for a sizable proportion of macroinvertebrate diversity. Ice and snow are melting particularly rapidly with ongoing climate change in the tropical Andean cryosphere, and studies like this are important for understanding the role of glacier-fed streams on biodiversity before they disappear.

Brynn Kayhill (Primary Presenter/Author), Missouri State University , bek893s@missouristate.edu;

Andrea Encalada (Co-Presenter/Co-Author), Universidad San Francisco de Quito , aencalada@usfq.edu.ec ;

Debra Finn (Co-Presenter/Co-Author), Missouri State University , dfinn@missouristate.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

A meta-analysis of aquatic plant demographic and trait responses to changes in precipitation regimes Climate change is predicted to alter global precipitation regimes, with consequences for plant growth, trait expression, and physiological function. Plants contribute strongly to ecosystem functions, acting as natural water filters and resources for animals. Thus, the effects of altered water availability can potentially cascade up to produce community and ecosystem scale outcomes. How plants respond to changes in water availability is expected to be a function of the evolution of their life-history strategies in response to particular environmental conditions. The evolution of these strategies can influence whether plants respond (or do not respond) to shifts in water availability through demographic changes, morphological plasticity, or altered physiological regulation and function. The effects of changes in water availability, typically water reduction, on plants have received extensive attention in terrestrial systems. However, the response of aquatic plants to changes in water availability is far less understood and a synthesis of how changes in water supply affect plant demography and traits is lacking. Here, we present a global meta-analysis of plant responses to increases and decreases in water availability across aquatic systems. We test for overall responses across these environments to reductions and increases in water availability. Additionally, we test for variation in the mechanisms of plant responses and their magnitude across different plant taxa. Through this synthesis, it becomes possible to not only predict how plants will respond to climate change and glean insights into the ecological and evolutionary mechanisms that shape these responses through time.

Joseph Braasch (Primary Presenter/Author), Rutgers University Camden , jb1950@camden.rutgers.edu;

Angélica González (Co-Presenter/Co-Author), Rutgers University , ag1271@camden.rutgers.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

CHANGES IN UPLAND, RIPARIAN, AND STREAMBED SEDIMENT C:N AND ASSOCIATED WATER QUALITY IN RESPONSE TO AGRICULTURAL ACTIVITY Converting forests to cropland is often associated with nitrogen inputs to soils, which drive a decrease in soil C:N. Excess nitrogen is leached from the soil and enters surface waters, where it contributes to eutrophication. Restoring riparian buffers along crop fields has the potential to drastically reduce the amount of nitrogen entering surface waters. This study examined variations in water quality and soil/sediment C:N in forested versus agricultural watersheds, with and without forested riparian zones. Six streams were chosen: 3 in forested watersheds (control), and 3 in forested watersheds (experimental). Of the experimental watersheds, one had a well-established buffer (BDF), one had no buffer (MOF), and one had a grassy buffer (CB-Ag). Water samples were taken upstream and downstream of sample sites to monitor changes in water chemistry. The study found, as expected, that soil C:N was lower in agricultural systems compared to forested systems. This supports the assumption that excess nitrogen is accumulating in agricultural soils. C:N decreased moving from upland soils to stream sediments in the site without a riparian buffer. Both sites with buffers saw an increase in soil C:N within the buffer and in the stream, which suggests uptake or removal of nitrogen in the riparian zone. These findings support the premise that restoring riparian buffers is vital to reducing nutrient runoff from crop fields into surface waters.

Kayleigh Hummel (Primary Presenter/Author), University of New Hampshire , kah1121@unh.edu;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire , wil.wollheim@unh.edu;

Lara Munro (Co-Presenter/Co-Author), University of New Hampshire , lara.munro@unh.edu;

Shaad Mahmud (Co-Presenter/Co-Author), University of New Hampshire , shaad.mahmud@unh.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Aqueous Temperature Spatial-Temporal Trends Linked to Climate Change and Land Use in the Delaware River Watershed Impacts of climate change on watersheds will manifest in alterations of abiotic and biotic processes. However, detecting and managing these impacts is challenging because the changes are heterogeneous in time and space. Our research question is to determine if watershed restoration mutes the climate driven changes to water temperature in the Delaware River watershed. This analysis requires addressing issues of missing data, varied site characteristics, and a limited length of time-series data. To combat those challenges, we will model missing data, aggregate data from multiple sources (Delaware River Watershed Initiative, Monitor My Watershed, and USGS), define seasonality and trends throughout the data, and model the trends in a spatial stream network (SSN) format across the entire Delaware River watershed. Our SSN will incorporate spatial correlation and allow us to define temperature trends as a function of restorations and land use/land cover. While restoration efforts are not uniform in design or scale, our approach allows us to extract these relationships despite additive uncertainty from modeled estimates of missing data and SSN model uncertainty. Time-series trend analysis is always limited by the number of years available in the data, and trend components are stochastic, but our available data covers ten years, a wide range of stream orders, and varying localized conditions which will allow us to capture the effects of climate change on water temperature in the Delaware River watershed.

Melissa Bross (Primary Presenter/Author), The Academy of Natural Sciences of Drexel University , mab582@drexel.edu;

Timothy Maguire (Co-Presenter/Co-Author), The Academy of Natural Sciences of Drexel University , tjm438@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

INVASIVE EFFECTS OF AILANTHUS ALTISSMA ON FRESHWATER MACROINVERTEBRATE COMMUNITIES The exponential growth of invasive species has caused devastating effects to freshwater and terrestrial habitats. The competitive advantages of invasive species include outcompeting native species for natural resources, which results in habitat loss and localized extinction of native species. To comprehend the impact of invasive plant species we studied the allochthonous leaf litter inputs of riparian Ailanthus altissima (Tree of Heaven) on freshwater macroinvertebrate communities. Specifically, we surveyed invasive leaf litter effects on 1) macroinvertebrate density and diversity, and 2) unique macroinvertebrate functional feeding group (FFG) abundance compared to leaf litter from native tree species. The study was accomplished by deploying artificial leaf packs into a perennial stream using three treatments: invasive leaf litter, native leaf litter, and a mix of both litters. Leaf packs were anchored in the stream (n = 25 leaf packs treatment-1; n = 75 leaf packs total) and a subset was harvested weekly (n = 5 leaf packs treatment-1) for five to six weeks. Results of the experiment demonstrated that macroinvertebrate density and FFG relative abundances were reduced in the invasive leaf packs compared to native leaf packs, with the mixed leaf packs supporting the greatest macroinvertebrate density and FFG relative abundance over time. This study highlights that allochthonous materials from riparian invasive plant species can affect freshwater macroinvertebrate communities, potentially altering freshwater ecosystem processes.

Andrew Alba (Primary Presenter/Author), CALIFORNIA STATE UNIVERSITY BAKERSFIELD , aalba7@csub.edu;

Jonathan Juarez (Co-Presenter/Co-Author), California State University Bakersfield , j_juarez123@yahoo.com;

Rae McNeish (Co-Presenter/Co-Author), California State University Bakersfield , rae.mcneish@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Assessment of nutrient transport and exchange in the tributary of the Lancang-Mekong River, A case study of the Mun and Chi Rivers in Thailand The Mun and Chi Rivers hold significant importance as vital tributaries within the Lancang-Mekong Basin, a region supporting a population exceeding 10 million people heavily reliant on the abundant water resources and rich biodiversity it provides. Furthermore, these tributaries serve as crucial agricultural resources in Thailand, playing a pivotal role in sustaining the economic well-being of the northeastern region. Understanding the intricate dynamics of mineral and nutrient transport from the Mun and Chi Rivers into the Lancang-Mekong River is imperative for the functioning of the lower Mekong ecosystem. Comprehensive research is required to unravel the intricate connections governing the flow of minerals and nutrients between these tributaries and the Lancang-Mekong Rivers, addressing existing knowledge gaps. Specifically, a meticulous evaluation of the mineral and nutrient exchange at the confluence point of the Mun and Chi Rivers in Sisaket and Ubon Ratchathani provinces is essential. Equally important is the assessment of mineral and nutrient levels in the Mun River downstream of the Chi River confluence before its merger with the Lancang-Mekong River in Ubon Ratchathani Province. This study seeks to estimate the transport of minerals and nutrients in the Mun and Chi Rivers both before and after their junction, as well as the mineral and nutrient transport in the Mun River at its mouth in Ubon Ratchathani Province prior to entering the Lancang-Mekong River.

Pavisorn Chuenchum (Primary Presenter/Author), Chulalongkorn University , Pavisorn.C@chula.ac.th;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

FROM HEADWATERS TO THE VALLEY: INVESTIGATING THE RIVER CONTINUUM CONCEPT IN THE ARID ENVIRONMENT Headwater streams are sensitive freshwater ecosystems due to their small size, making headwaters vulnerable to physical disturbances like erosion and sedimentation, also could be changed through climate change, which can alter flow regimes and habitat availability. The river continuum concept (RCC) serves as a guide for understanding terrestrial-aquatic connections throughout river systems located in deciduous forests. We investigated if the RCC developed for eastern deciduous forests is applicable to the river systems located in California’s arid climate across an elevation gradient. Aquatic macroinvertebrate, nutrient, and energy resources sample collection and processing is in progress (n = 10 sites). Surber samplers were used to collect aquatic macroinvertebrate samples, colorimetric methods were used to determine nutrient concentration, and total dry mass of allochthonous materials was determined. Results are expected to demonstrate that stream allochthonous energy sources will dominate the headwaters in the high elevation mountains with energy sources shifting to autochthonous sources as the river systems transition to the valley ecosystem with less riparian forest cover. In addition, we expect that the aquatic macroinvertebrate community composition will shift with energy sources within the stream systems. Specifically, the macroinvertebrate community will be dominated by the shredder and collector-gatherer functional feeding groups in the higher elevations. And the collector-filterer and scraper-grazer functional feeding groups dominating the macroinvertebrate community in valley streams. These results will highlight the RCC’s ability to be applied to different environment throughout the United States and can contributing to potential management and restoration efforts that support functioning freshwater streams.

Isaac Owens (Primary Presenter/Author), California State University of Bakersfield , iowens@csub.edu;

Rae McNeish (Co-Presenter/Co-Author), California State University Bakersfield , rae.mcneish@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Exploring Morphological Plasticity of Arundinaria gigantea, or Rivercane, in Response to Light Variability: an Arkansas Field Study Arundinaria gigantea, or rivercane, is an endangered riparian bamboo species in the Southeast United States undergoing significant restoration efforts led by the Rivercane Restoration Alliance. Rivercane is organized in groupings called canebrakes, which house birds, mammals, and invertebrates, including some threatened species, like the Swainson’s Warbler. Rivercane is also a culturally significant species, prized by Southeastern Native tribes for functions like architecture, baskets, and instruments. Restoration of rivercane demands data on rivercane growth and density in differing environments so that sites can be prioritized. Rivercane is a clonal plant that spans the understory and forest gaps, but the dynamics of rivercane morphology and density within low- and high-light environments remain underexplored. To address this, we conducted a field study in the Ozark Highlands, Arkansas, focusing on morphological and biomass differences between two light treatments. Nine sites were selected in Summer 2023, and within each canebrake, high- and low-light areas were identified using a LI-COR light meter. At each site, data were collected on cane size, cane density, and biomass. There were significant differences in total biomass across sites (R2=0.86, p<0.001), and in general total biomass was higher in open canopy sites (p<0.001). Preliminary analysis indicates no difference in density between high- and low-light areas across all sites (p=0.85). We found an average density of 4.04 culms m-2 in the low-light areas and 4.18 culms m-2 in the high-light areas across all sites. Densities are more than three times lower than those reported in previous studies.

Emily Carter (Primary Presenter/Author), University of Arkansas , emilyc@uark.edu;

Michelle Evans-White (Co-Presenter/Co-Author), University of Arkansas , mevanswh@uark.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Seasonality and urbanization effects on basal resource elemental standing stocks in Central Arkansas streams Anthropogenic land use can strongly alter the quantity and quality of basal resources in stream food webs, but these effects are likely seasonally-dependent and different across resources. We measured basal resource standing stocks and elemental composition (carbon (C), nitrogen (N), and phosphorus (P)) in 15 headwater streams during winter and summer of 2022. Sites were selected from predominantly forested (n=5) or urban catchments (n=10) in Central Arkansas, USA. Among the urban streams, sites were separated in half by locally open or closed canopy. We determined areal C, N, and P standing stocks (g/m2) in epilithic periphyton, coarse particulate organic matter (CPOM), and benthic fine particulate organic matter (FPOM). Compared to urban streams, forested streams exhibited significantly greater C and N stocks as CPOM, especially during winter, whereas urban open canopy streams exhibited significantly greater C stocks as periphyton during summer. Urban streams also had significantly greater P stocks in the form of FPOM and periphyton, as compared to forested streams, during both seasons. Across all streams, CPOM was generally the largest areal stock (average 80%, 58%, and 59% of C, N, and P, respectively) and FPOM was the smallest areal stock, although periphyton N and P stocks approached or exceeded CPOM N and P stocks in urban streams with open canopy. These trends suggest that urbanization consistently increases N and P storage in FPOM and periphyton, and canopy openness can exacerbate urban shifts at the trophic base of stream food webs by decreasing CPOM quantity and increasing periphyton quantity.

Halvor Halvorson (Primary Presenter/Author), University of Central Arkansas , hhalvorson@uca.edu;

Anthony Pignatelli (Co-Presenter/Co-Author), University of South Carolina , PIGNATEA@email.sc.edu;

Emily Walsh (Co-Presenter/Co-Author), University of Central Arkansas , ewalsh1@cub.uca.edu;

Matthew Connolly (Co-Presenter/Co-Author), University of Central Arkansas , mconnolly@uca.edu;

Eric Moody (Co-Presenter/Co-Author), Middlebury College , erickmoody@gmail.com;

Erin Larson (Co-Presenter/Co-Author), University of Alaska-Anchorage , ern.larson@gmail.com;

Steven Thomas (Co-Presenter/Co-Author), University of Alabama , sathomas16@ua.edu;

Jessica Corman (Co-Presenter/Co-Author), University of Nebraska-Lincoln , jcorman3@unl.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Stream consumer-resource stoichiometry across an agricultural gradient in the Arkansas River Valley, USA. Over 280,000 U.S. stream miles are impaired due to nutrient pollution by nitrogen (N) and phosphorus (P). The leading cause of nutrient pollution in the U.S. is due to agricultural practices, but few studies have investigated the stoichiometric impacts of agriculturally-derived nutrient pollution on stream food webs. To study the impacts of agricultural land-use/land-cover on benthic macroinvertebrate consumer-resource stoichiometry, we measured the stoichiometric composition of larval macroinvertebrates and their foods (coarse particulate organic matter, fine particulate organic matter, and periphyton). Sampling occurred from May-June across eight headwater streams ranging from <1% to 72% pasture/hay land-cover within the Arkansas River Valley. Preliminary data show positive trends of increased %P in basal resources alongside increased pasture/hay land-cover, especially in periphyton. Macroinvertebrates appeared to be relatively consistent in their %P regardless of pasture/hay land-cover. However, macroinvertebrate family richness (R) decreased in response to increased %pasture/hay (lowest %pasture/hay land-cover R=15, highest %pasture/hay land-cover R=5). Excess P from pasture/hay within the watershed of headwater streams may become incorporated into the basal resources of macroinvertebrates, resulting in shifts in the macroinvertebrate community composition towards taxa that are better able to process basal resources with elevated %P. Agricultural P pollution may result in stream degradation via alteration of the stoichiometric composition of the stream’s basal resources, resulting in altered food web structure. In the future, P data will be paired with carbon (C) and N data, enabling us to study shifts in the C:nutrient ratios of macroinvertebrate consumers and their resources.

Eli Wess (Primary Presenter/Author), University of Central Arkansas , ewess@cub.uca.edu;

Halvor Halvorson (Co-Presenter/Co-Author), University of Central Arkansas , hhalvorson@uca.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

THRESHOLD ELEMENTAL RATIOS OF STREAM SESTON Stoichiometric and thermodynamic constraints help explain observed non-linear, negative relationships among concentrations of dissolved organic carbon (resource quantity) and nutrient elements such as nitrogen (N) and phosphorus (P) and related solute pairs, such as nitrate and ammonium. However, few studies have explored whether the carbon:nutrient ratios of particles transported via streams (seston) are similarly constrained, either stoichiometrically or thermodynamically. Here, we combined the threshold elemental ratio (TER) concept with consideration of oxidation-reduction (redox) biogeochemistry to define thresholds in seston elemental content that could integrate signals of seston-associated microbial activity vs. substrate demand. We used seston and solute data from 27 National Ecological Observatory Network (NEON) wadeable stream sites collected from 2014-2023. Our analysis revealed that seston elemental ratios exhibit clear thresholds relative to both carbon quantity (total organic carbon, TOC) and the availability of alternative electron acceptors used by microorganisms to decompose organic carbon (nitrate, manganese, iron, sulfate), indicating fundamental constraints on seston elemental content. Specifically, the seston C:N threshold relative to TOC concentration was ~3:1, and for seston C:P it was ~5:1. Seston C, N and P each showed non-linear (asymptotic), negative relationships with nitrate, manganese, iron, and sulfate, indicating that redox biogeochemistry also potentially plays a role in the elemental content of stream seston. Overall, applying TER models to seston elemental content in this way could help identify and integrate the dual role of stoichiometric and thermodynamic constraints on bulk seston C:N:P content.

David Manning (Primary Presenter/Author), University of Nebraska at Omaha , davidmanning@unomaha.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama , jbenstead@ua.edu;

Zacharie Loveless (Co-Presenter/Co-Author), The Unversity of Alabama , ztloveless@crimson.ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

DRIVERS OF VARIATION IN BODY STOICHIOMETRY OF RIFFLE BEETLES Stoichiometric traits (such as C:P or N:P ratios) of aquatic macroinvertebrates help elucidate relationships between organisms’ body chemistry, biological processes, and abiotic conditions. By looking at body stoichiometry of aquatic macroinvertebrates, we can better understand how these nutrients are differentially used by organisms across life stages, geographic gradients, and evolutionary lineages. Among benthic macroinvertebrate groups, riffle beetles (Elmidae) are a diverse lineage spanning a broad geographic range and thus serve as an ideal group in which to test these questions. We collected macroinvertebrate samples from NEON sites across the United States and processed them for body %C, %N, and %P to create a database of body stoichiometry for aquatic macroinvertebrate genera. Within Elmidae, average body %P varied with life stage, genus, and latitude. Adult elmids had lower average %P than their larval counterparts, supporting the growth rate hypothesis as larval growth rates likely are greater than those of adults. Furthermore, there were differences in body %P between genera. For example, adult Hexacylloepus exhibited significantly higher body %P than its larval counterpart and the adults of Optioservus and Macrelmis. Lastly, there were latitudinal differences in body %P. Adult elmids at the highest latitudes had the lowest body %P, with body %P tending to increase at lower latitudes. The differences between these elemental ratios indicate that evolutionary history, geographic variation, and ecological differences between larvae and adults contribute to elmids’ differing elemental needs. These stoichiometric differences also demonstrate the need for further research to make clearer the mechanisms of difference.

Emma Neill (Primary Presenter/Author), Middlebury College , neill.emmad@gmail.com;

Baker Angstman (Co-Presenter/Co-Author), Middlebury College , bangstman@middlebury.edu;

Qiting Cai (Co-Presenter/Co-Author), University of California Santa Cruz , qcai17@ucsc.edu;

Julia Keon (Co-Presenter/Co-Author), Middlebury College , jskeon@middlebury.edu;

Natalie Montano (Co-Presenter/Co-Author), Middlebury College , nmmontano@outlook.com;

Elizabeth Peebles (Co-Presenter/Co-Author), Harvard T.H. Chan School of Public Health , epeebles@hsph.harvard.edu;

Ella Roelofs (Co-Presenter/Co-Author), Middlebury College , groelofs@middlebury.edu;

A.J. Rossbach (Co-Presenter/Co-Author), Middlebury College , arossbach@middlebury.edu;

Sophie Schuele (Co-Presenter/Co-Author), Middlebury College , sschuele@middlebury.edu;

Liza Toll (Co-Presenter/Co-Author), Middlebury College , etoll@middlebury.edu;

Molly Costanza-Robinson (Co-Presenter/Co-Author), Middlebury College , mcostanz@middlebury.edu;

Eric Moody (Co-Presenter/Co-Author), Middlebury College , erickmoody@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Detection of Zn2+ and Cd2+ using an ion specific low-molecular-weight fluorescence probe in Chironomidae larvae, Rheocricotopus spp. The uptake and accumulation of metal ions in freshwater benthic organisms are often determined using analytical techniques. However, ion-specific low-molecular-weight fluorescence probes have become increasingly significant in the field of cell biology due to their easy technical operability and high affinity for metal ions. Although these probes are interesting alternatives for detecting small concentrations of metal ions, this technology is not frequently used to assess ion uptake and tissue distribution in whole-body aquatic insect larvae. In this study, the uptake and distribution of Zn2+ and Cd2+ in Chironomidae larvae, Rheocricotopus spp., were separately evaluated using novel low-molecular-weight Zn2+ and Cd2+-selective fluorescence probes, with and without dissolved humic acids (HAs). The chironomid larvae were exposed to various concentrations of Zn and Cd along with 0, 1, 10, and 50 mg/L of dissolved HAs for 48 hours and then incubated with the ion-selective fluorescence probes. The results revealed that intercellular and intracellular Zn2+ and Cd2+ were mainly distributed in the midgut region of the larval body. However, Zn2+ appeared throughout the digestive tract, with low fluorescence intensities observed in the anal papilla. Additionally, the presence of dissolved HAs renders metal ions unavailable to the chironomid larvae, significantly reducing their concentration in the larval body. This study provides insights into the potential use of ion-selective low-molecular-weight fluorescence probes to detect metal pollution and understand the toxicological implications of metals in aquatic insect larvae.

Ashok Kumar Shrestha (Primary Presenter/Author), Saitama University , shresthanirantar09@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Working Toward a Comprehensive Checklist for PA Chironomidae Species checklists are invaluable resources for biologists and conservationists. Unfortunately, there is currently no checklist for the Chironomids of Pennsylvania. Chironomids are effective freshwater bioindicators, but their usefulness is limited by their difficulty to identify as larvae. Having a checklist of species known to be found in a specific location can help researchers narrow down the potential species they are working with. This can help with identification, as well as with efforts to conserve rare or ecologically important species. To this end, a list of species known from Pennsylvania is being compiled using existing literature, museum collections, and DNA data. Highlighted here will be the sources where data is being collected from as well as a brief description of how the checklist is being put together and why it is important.

Duncan Brown (Primary Presenter/Author), Academy of Natural Sciences of Drexel University , db3536@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

What chemosensory cues do Chironomid midge larvae use for evaluating food resources of differing qualities? Midge larvae are often found in high densities in fine sediments that are rich in organic matter. Prior studies have documented their ability to select substrates with higher levels of food, but the exact cues (visual or chemosensory) they use to locate and evaluate food resources are not well-described. The purpose of this project was to find out if individual nutrients play a role in how aquatic midges use their chemosensory cues to find the most nutritional food sources. Larval behaviors were investigated while they were searching for and settling on artificial diets enriched with different quantities of protein, sugars, amino acids, and algae. In one experiment larvae located food in complete darkness within 1 hour, supporting the hypothesis that chemosensory cues, rather than visual cues are involved. Larvae exhibited preference for diets containing higher protein and glucose. Additional experiments are underway to test the attractiveness of diets enriched in free amino acids and algae. Understanding how these aquatic insects detect higher quality food is important because it can help us eventually know how they cope with environmental stressors by settling in habitats with higher food quality. Also, looking at tissue biomarkers such as hemoglobin, heat shock, or oxidative damage on tissue could help us learn more about how physiological stress might impact their ability to orient to food.

Brittney Sargent (Primary Presenter/Author), Ohio University , bs873119@ohio.edu;

Kelly Johnson (Co-Presenter/Co-Author), Ohio University , johnsok3@ohio.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Chironomid-Plant Relationships in Response to Revegetation in Lake Austin and Lady Bird Lake Lake Austin and Lady Bird Lake are adjoining reservoirs located in Austin, Texas. Sterile grass carp were introduced into Lake Austin as a biocontrol agent to control the invasive aquatic plant Hydrilla verticillata. This practice nearly eliminated Hydrilla but also resulted in the decline of native aquatic vegetation and led to increased shoreline erosion and the colonization of other nuisance species. Conservation efforts to reestablish the vegetation are underway. Epiphytic macroinvertebrate assemblages are being used to assess the success of this restoration. Chironomidae, a large and diverse insect family, are often the dominant epiphytic macroinvertebrate. Due to the tedious identification process, chironomids are typically identified to the family level in ecological studies, minimizing their ability to contribute to the detection of ecological patterns. Through further identification of the chironomids to the genus level, this study evaluated the chironomid taxonomic sufficiency required to identify ecological patterns to facilitate management decisions. The results demonstrate that the identification of Chironomids beyond the family level is necessary to identify these patterns and identify the best conservation practices.

James Shugart (Primary Presenter/Author), University of North Texas , jamesshugart@my.unt.edu;

Katie Vasquez (Co-Presenter/Co-Author), University of North Texas , katievasquez@my.unt.edu;

James Kennedy (Co-Presenter/Co-Author), University of North Texas , james.kennedy@unt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

DISTINGUISHING THE EFFECTS OF SELENIUM FORMS AND CONCENTRATIONS ON BIOACCUMULATION AND LETHALITY TO AQUATIC INSECT COMMUNITIES IN STREAM MESOCOSMS. Mines in the Elk River Valley in British Columbia have been active since the 1880s. These mines have caused elevated selenium levels in surface waters flowing into the United States. While selenium is essential for life, its accumulation in food webs can be toxic to wildlife. This study aims to investigate the bioaccumulation rates and potential toxic effects of two water-soluble inorganic selenium compounds, selenate (Se 6+) and selenite (Se 4+), on benthic communities in stream ecosystems. Selenite is generally more bioavailable and is more toxic at lower concentrations, but the interactive effects of selenium forms and concentrations on accumulation are poorly understood. Selenite and selenate will be added at varying concentrations to 36 stream mesocosms. Each mesocosm represents a small-scale stream ecosystem comprised of rocks, native water, algae, and invertebrates. Each experimental stream will receive selenite or selenate, or a mixture of both (1:10 ratio selenite: selenate) for 30 days. Total selenium concentrations in treatments will range from 0.5 ug/L to 100 ug/L. Each treatment will be duplicated, whereas the control (near zero total selenium) will be quadrupled. Sediment, algae, macroinvertebrates, and adult aquatic insect samples will be collected to quantify accumulated total selenium. Additionally, dissolved selenium, selenium species, and ancillary water-quality parameters (specific conductance, temperature, pH, etc.) will be collected regularly in all exposed water. This poster will highlight relevant background information on the experimental design and analysis plan.

Molly Moloney (Primary Presenter/Author), USGS , mmoloney@usgs.gov;

Madison Foster (Co-Presenter/Co-Author), USGS , madisonjfoster@gmail.com;

Travis Schmidt (Co-Presenter/Co-Author), USGS WY-MT Water Science Center , tschmidt@usgs.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

INTERACTIONS BETWEEN MICROPLASTICS, THE ANTIMICROBIAL COMPOUND TRICLOSAN, AND MICROBIAL BIOFILM COMMUNITIES IN FRESHWATER ECOSYSTEMS Microplastics (MPs), defined as plastics less than 5mm in diameter, are ubiquitous contaminants in freshwater systems that could be hotspots for the interaction of antimicrobial compounds and microbial biofilms. Triclosan is a synthetic, broad-spectrum antimicrobial compound and a common contaminant in surface waters and sediments. MPs and antimicrobials are common in untreated wastewater, within wastewater treatment systems, and in treated wastewater effluent. Due to high surface area and hydrophobicity, many MPs adsorb contaminants like antimicrobials to their surface. Adsorbed antimicrobials could affect biofilms that colonize MPs, altering their diversity and composition and selecting for resistant traits and taxa. Using a microcosm approach, we assessed the potential for triclosan to adsorb to MP fibers and alter the taxonomic composition and resistance capacity of bacterial and algal communities in MP biofilms. We exposed acrylic, nylon, and polyester MP fibers to triclosan and measured its adsorption to each. Experimental microcosms containing triclosan-exposed or control fibers of each polymer type and water from the Chicago River were incubated in the lab for 30 days. Polyester adsorbed the most triclosan (2.5 ng / fiber) and nylon the least (0.2 ng / fiber). We analyzed bacterial and algal communities via high-throughput amplicon sequencing. Exposure to triclosan significantly changed the taxonomic composition of both bacterial and algal communities attached to MP fibers and in the water column. These results suggest that widespread MP and triclosan contamination could potentially alter bacterial and algal biofilm communities.

Ryan Krantz (Primary Presenter/Author), Loyola University Chicago , rkrantz@luc.edu;

Justine Nguyen (Co-Presenter/Co-Author), Loyola University Chicago , justine.nguyen@marquette.edu;

Kathryn Renyer (Co-Presenter/Co-Author), Loyola University Chicago , krenyer@live.com;

Paul Chiarelli (Co-Presenter/Co-Author), Loyola University Chicago , mchiare@luc.edu;

Timothy Hoellein (Co-Presenter/Co-Author), Loyola University Chicago , thoellein@luc.edu;

John Kelly (Co-Presenter/Co-Author), Loyola University Chicago , Jkelly7@luc.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Environmental determinants of fishery yield in one of the world’s largest tropical flood pulse system The Tonle Sap Lake and River (TSLR) ecosystem in the Lower Mekong Basin (LMB) is one of the world's most productive inland fisheries. Many studies in LMB have focused mainly on catch weight, abundance, fish ecology, taxonomic diversity and spatiotemporal dynamics of fish assemblages. However, no temporal analyses by functional fish traits have been studied for the fishes in LMB to inform fisheries policies. Here, we describe temporal variability of fish catches by traits in the Tonle Sap dai fishery, the largest commercial fishery in the Mekong Basin, and the environmental drivers determine the variability. We analyze 17-year time-series (2000–2017) data on the fishery’s catches composing of 119 species with 26 traits. We found that traits with highly significantly declining catch in the Dai fishery were disproportionately represented by large-sized, carnivorous and long-distance migratory fishes, fishes preferring demersal and pelagic habitats in the water column and fishes feeding higher in the tropic position (> 2.76). The largest portion of variance for the changes in the dai catch by traits is explained by precipitation, water level, flooded forest, and maximum air temperature. This study stresses a dire need for sustainable decisions on fish catch by species?specific traits and essential information for effective fishery regulation and management.

Pin Kakada (Primary Presenter/Author), Royal University of Phnom Penh , pin.kakada77@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

From Staple Food to Scarce Resource: The Population Status of an Endangered Striped Catfish Pangasianodon hypophthalmus in the Mekong River, Cambodia Striped catfish Pangasianodon hypophthalmus (Sauvage, 1878) is a flagship catfish species of the Mekong River region, a commercially valuable food fish, and a popular aquaculture species in many Asian countries. The species was assessed as “Endangered” by the International Union for Conservation of Nature (IUCN) due to range contraction and declining abundance, though the status of the species’ wild population in Cambodia, a critical habitat for the species, is not well understood. Here, we assess the population status of the striped catfish in Cambodia using multiple sources, including time-series catch data and length frequency distribution data from a commercial fishery operated in the Tonle Sap River from 1998/99 to 2017/18 and larval drift data monitored in the Mekong River from 2004 to 2018. We found that there was a significant decline in the catch (metric tonnes) of the striped catfish. Similarly, length-based indicator analysis indicates that striped catfish mean length and abundance have both declined over the study period. Moreover, long-term larval drift monitoring in Mekong River shows that there was a marginally significant decline in the quantity of striped catfish larvae/juvenile drifting downstream to the lower floodplain over the last decade. Both larval fish abundance and floodplain fish harvests have a significant positive relationship with Mekong flow and flood extent. Therefore, actions such as maintaining natural seasonal flows to the Tonle Sap floodplain and protecting migratory fish stocks from overharvest and habitat fragmentation are essential to the persistence of stocks of striped catfish and other large-bodied migratory fishes.

Sothearith Soem (Primary Presenter/Author), Royal University of Agriculture, Faculty of Fisheries and Aquaculture , thearithsoem12345@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

A Meta-Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in the Biota of the Laurentian Great Lakes Per- and polyfluoroalkyl substances (PFAS) are a family of synthetic organofluorine chemicals with over 15,000 recognized congeners. The strong C-F bonds and electrostatic interactions of these organofluorines, especially of the PFCA (perfluorinated carboxylic acids) and PFSA (perfluorinated sulfonic acids) subgroups, make them resistant to degradation, bioaccumulative, and toxic to biota. To assess gaps in our knowledge of PFAS dynamics in freshwater ecosystems, we performed a systematic, statistically-rigorous meta-analysis of PFAS distributions and spatiotemporal variance in the biota of the Laurentian Great Lakes' watersheds. We reviewed 45 publications from the past 25 years and focused on PFCAs, PFSAs, and emerging precursor/replacement compounds that have been consistently detected in biological tissues. Preliminary analysis suggests that, while biomagnification and bioconcentration pathways explain some of the variation in contaminant concentrations, total PFAS burden is intrinsically linked to an organism's life history and habitat preference. While Lake Superior tends to have lower concentrations of PFAS relative to industrially-contaminated Lake Ontario, we found substantial within-lake heterogeneity, especially in groups like herring gulls: the average concentration of PFOS in gull eggs across years in Lake Superior was 119 ± 75 ng/g w.w. versus 424 ± 405 ng/g w.w. in Lake Ontario; n = 6 publications. Our review also revealed that Lake Michigan and the Canadian shores of Lake Superior and Huron remain comparatively underrepresented in the literature. Synthesizing the environmental abundance of these contaminants in the Great Lakes will provide an important benchmark for current knowledge, and inform future scientific research, policy decisions, and restoration efforts.

Peter Martin (Primary Presenter/Author), University of Notre Dame , pmarti23@nd.edu;

Daniele Miranda (Co-Presenter/Co-Author), University of Notre Dame , ddealmei@nd.edu;

Alison Zachritz (Co-Presenter/Co-Author), University of Notre Dame , azachrit@nd.edu;

Sarah Klepinger (Co-Presenter/Co-Author), University of Notre Dame , skleping@nd.edu;

Juan Flores (Co-Presenter/Co-Author), University of Notre Dame , jflores9@nd.edu;

Therese Reisch (Co-Presenter/Co-Author), University of Notre Dame , treisch@nd.edu;

Whitney Conard (Co-Presenter/Co-Author), University of Notre Dame , whitneymconard@gmail.com;

Gary Lamberti (Co-Presenter/Co-Author), University of Notre Dame , glambert@nd.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Evaluation of Climate Change Impacts on Floods and Droughts in Stung Sen Basin using SWAT Model Climate change can result in fluctuations in flooded areas, and the frequency and duration of droughts. The outcome is contingent on anticipated climate changes whether wetter or drier and their interaction with local conditions. This study aims to evaluate the impact of climate change by assessing the percentages of flood and drought magnitudes in Stung Sen basin using the SWAT model. The evaluation of the calibration model is shown very good statistics indicators such as NSE=0.81, RSR=0.44, and PBIAS=-0.48%, and the validation also displayed a great performance with NSE=0.87, RSR=0.37, and PBIAS=-2.01%. The result of the daily streamflow simulation in baseline (1985-2013) was used to compare with the daily streamflow under the scenarios of climate change. There are 3 different GCMs projected climate change models with a low and a high emission rate of greenhouse gas and return interval in the 2030s and the 2060s. As results illustrated that the magnitude of the extreme floods would become more increase for wet overall (GFDL-CM3) and increased seasonal variability (IPSL-CM5A-MR) models for both time horizons, except dry overall (GISS-E2-R-CC) model which is reminded decrease the magnitude of the flood. The dry overall (GISS-E2-R-CC) and increase seasonal variability (IPSL-CM5A-MR) models will be increased droughts magnitude for both horizon years. In contrast, the wet overall (GFDL-CM3) model results in a decrease in the magnitude of droughts for both low and high emission rates. The percentage changes of floods and droughts magnitude under climate change scenarios in streamflow likely depend on the chosen hydrological model.

Bunhak CHHUONG (Primary Presenter/Author), Institute of Technology of Cambodia , chhuong.bunhak@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

EFFECTS OF BODY SIZE AND SEASON ON TOTAL AND METHYL MERCURY CONCENTRATIONS IN ORB-WEAVING SPIDERS Riparian spiders have been proposed as sentinels of bioaccumulative contaminants, like methylmercury (MeHg). Riparian spiders become contaminated with MeHg when they feed on emergent aquatic insects and concentrations of MeHg in riparian spiders reflect the level of contamination of the aquatic food web. Although previous studies suggest riparian spiders have potential as sentinels of MeHg, few studies have examined how MeHg concentrations in riparian spiders vary seasonally. We sampled two genera of orb-weaving spiders (Araneidae: Larinioides sp. and Metazygia sp.) monthly from May-September 2019 at a private boat dock on Eagle Mountain Lake, Texas. We collected 574 spiders and separated them by, genera, size class and month of collection into composite samples. The samples were then analyzed for total Hg (THg, inorganic+MeHg) and MeHg. We observed no difference in THg concentration between genera and so combined them for subsequent analyses. During most months we observed a positive correlation between THg concentration and spider size, indicative of age-dependent Hg bioaccumulation, but the slope of the relationship between THg and size increased throughout the summer. As a consequence, the highest concentrations of THg occurred in the largest spiders in late summer and fall. Unlike, total Hg, MeHg concentrations were low and remained constant over the course of the study, resulting in a steady decrease in %MeHg in spider tissues. We hypothesize that these patterns were caused by an increasing reliance on terrestrial insect prey (with low % of MeHg) through the summer.

Matthew Chumchal (Primary Presenter/Author), Texas Christian University , m.m.chumchal@tcu.edu;

Ray Drenner (Co-Presenter/Co-Author), Texas Christian University , r.drenner@tcu.edu;

Benjamin Barst (Co-Presenter/Co-Author), University of Alaska, Fairbanks , bdbarst@alaska.edu;

Olivia Eberwein (Co-Presenter/Co-Author), Texas Christian University , O.EBERWEIN@tcu.edu;

Maddy Hannappel (Co-Presenter/Co-Author), California Academy of Sciences , mphannappel@gmail.com;

Garrett Helburn (Co-Presenter/Co-Author), Texas Christian University , garrett.helburn@tcu.edu;

Cale Perry (Co-Presenter/Co-Author), Texas Christian University , cale.r.perry@tcu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Potential health effects to anurans of microplastic mixtures from point and nonpoint sources in San Antonio Greenways Among vertebrates, amphibians currently face the highest rate of extinction due to a myriad of environmental and anthropogenic factors. Apropos, little attention has been given to the impacts of emerging pollutants (i.e., microplastics) on amphibian health and contributory role to global declines. Aquatic ecosystems have also been documented as sink-sources for a variety of anthropogenic pollutants, especially microplastics (MP), originating across contrasting land-uses. In this study, 12 ephemeral pools were monitored monthly for amphibian activity in two urban intermittent river and ephemeral stream (IRES) systems of San Antonio, Texas. Two tadpole species were observed and sampled from each pool for MP ingestion; in the lab tadpoles were staged, weighed, measured, and identified. Fibers were the most abundant morphotype (~99%) across species and developmental stages. Potential MPs were marked and analyzed using Fourier Transformed Infrared Spectroscopy (FTIR) for confirmation and identification. Observed polymers ranged from fully synthetic blends of polyester to semi-synthetic cellulose acetate. Results regarding MP intake are currently being processed and MP characterizations can be reports during presentation. With the expansion of IRES systems globally, amidst ongoing climate change dynamics, it becomes crucial to understand how these reproductive habitats influence exposure to co-occurring amphibians.

Sue Ellen Gibbs-Huerta (Primary Presenter/Author), University of Texas at San Antonio , sueellen.fernandez@my.utsa.edu;

Andre Felton (Co-Presenter/Co-Author), University of Texas at San Antonio , andre.felton@my.utsa.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Analysis of Fire Retardant in Runoff As wildfires increase in intensity and frequency throughout California and the world, humans look for ways to mitigate impacts. One of those ways is spraying aerial fire retardant. While many different brands and concentrations are used in fighting wildfires, impacts on water chemistry and aquatic ecosystems are not known. We will simulate the application of fire retardant followed by a precipitation event to observe how much phosphorus is washed off. Working with the Big Sur Land Trust and the Central Coast Burn Association, I will apply 2 or more fire retardants to 1 m^2 plots and collect and analyze runoff samples after being filtered through the soil. We will then compare phosphorus concentrations in runoff from different fire retardants. With a more developed understanding of fire retardants, recommendations for wildfire management can be established to reduce negative impacts on aquatic ecosystems.

Alexandra Yokomizo (Primary Presenter/Author), California State University, Monterey Bay , aecyok@gmail.com;

John Olson (Co-Presenter/Co-Author), Dept of Applied Environmental Science, California State University Monterey Bay, CA, USA , joolson@csumb.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Assessing the Fluorescence Characteristics of Optical Brighteners in Rocky Mountain Streams Optical brightening agents (OBAs) are common fluorescent chemical additives to detergents and other household products and are indicative of untreated wastewater sources when present in streams. Differentiating the fluorescence of OBAs from other compounds such as naturally occurring organics requires knowledge of the specific excitation and emission wavelengths useful for detecting OBAs. We employed a two-phase experimental approach to assess the fluorescence characteristics of OBAs. First, we created a 5 by 5 grid of standard samples with 5 concentrations (0 ppm to 50 ppm) of artificial stream water (ASW) and 5 concentrations of OBAs. This allowed for the identification of optimal excitation-emission pairings where ASW fluorescence was least sensitive and OBA fluorescence was most sensitive. Subsequently, we sampled four local streams, split each sample into 5 parts, and added 5 known concentrations of OBAs ranging from 0 ppm to 50 ppm. Millipore water samples with similar added OBA concentrations were used as a control. And an excitation emission matrix was produced for each sample. We examined the correlation between emission intensity and OBA concentration for each combination of excitation and emission wavelengths to determine the wavelengths that yielded the strongest responses to OBA concentration with the least emission intensity interference from background stream-water organics. Our comprehensive analysis identified appropriate excitation and emission wavelengths to optimize detection of OBAs in Rocky Mountain Streams.

Jordyn Solliday (Primary Presenter/Author), Montana State University , jrsolliday@gmail.com;

Geoffrey Poole (Co-Presenter/Co-Author), Montana State University, Montana Institute on Ecosystems , gpoole@montana.edu ;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Mining Reclamation and Lake Recovery: Does One Influence the Other? Metal mining is critical during the wake of the green transition. A common environmental consequence of mining is downstream metal contamination of lakes. It is broadly presumed that anthropogenically-disturbed lakes recover over time, but this may not be true in metal-impacted systems. We investigated the biological and geochemical recovery of lakes affected by metal inputs from reclaimed mines that were subjected to different remediation actions. We analyzed the metal levels in the water, sediment, and benthic macroinvertebrates of three impacted lakes in northern Sweden. Preliminary results show that the metal levels in the sediments declined post reclamation, but the levels were still elevated, and presumably toxic to the macroinvertebrates. We found lower biodiversity where metal levels were highest. These results highlight that mining reclamation improves lake properties, but not to a high enough degree. Therefore, we encourage further development of reclamation efforts so that remediation adequately reduces the detrimental impact on surface waters.

Camila Urrea (Primary Presenter/Author), , maria.camila.urrea@umu.se;

Ryan Sponseller (Co-Presenter/Co-Author), Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden , ryan.sponseller@umu.se;

Christian Bigler (Co-Presenter/Co-Author), ;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Estimating decomposition rates of water stargrass (Heteranthera dubia), a potential N sink in a lowland agricultural river In streams, most nitrogen (N) removal occurs via assimilatory uptake, which results in the temporary removal of N. In some rivers, aquatic plants dominate N uptake and assimilation. In such rivers, aquatic plant decomposition rates and resultant N release influences N loads to downstream waterbodies. However, decomposition rates of aquatic plants are virtually unknown as most aquatic decomposition studies focus on allochthonous, terrestrial sources. We measured water stargrass (Heteranthera dubia, WSG) decomposition rates (-k) in the lower Yakima River (Washington, USA), where WSG grows across most of the channel width and heavily influences reach-scale metabolism and N uptake. We hypothesized that -k would be faster in coarse sediments (CS) compared to fine sediments (FS) due to higher oxygen concentrations. To test our hypothesis, we packed WSG in mesh bags then deployed six replicates each in (CS) and (FS) in the lower Yakima River. Each replicate had five mesh bags of WSG, and we removed one bag per replicate each week for five weeks. We dried each sample, measured dry mass, then calculated -k as the natural log of percent remaining. We found that -k did not vary by substrate (CS = 0.0095 ± 0.0027 d-1, range: 0.0045 – 0.0197 d-1, FS = 0.0094 ± 0.0015 d-1, range: 0.0051 – 0.0133 d-1). Interestingly, WSG had a slower -k compared to many allochthonous litter decomposition rates. Our preliminary results revealed that aquatic plants might decompose slower than allochthonous litter, resulting in a gradual release of assimilated N to downstream aquatic systems.

John Buster (Primary Presenter/Author), Washington State University (Tri-Cities) , john.buster@wsu.edu;

Aaron Pelly (Co-Presenter/Co-Author), Washington State University , aaron.pelly@wsu.edu;

Sarah Roley (Co-Presenter/Co-Author), Washington State University , sarah.roley@wsu.edu ;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

AN INVESTIGATION OF THE MACROPHYTE AZOLLA FILICULOIDES AND ITS RELATION TO NUTRIENTS AND HABITAT CHARACTERISTICS IN A PHOSPHORUS POLLUTED RIVER, IDAHO. Azolla filiculoides is an emergent aquatic fern native to the study area, the lower Portneuf River, Idaho. Azolla has a unique obligate symbiosis with a nitrogen-fixing cyanobacteria that is passed via reproduction. For this reason, phosphorus is expected to be the primary nutrient determining its growth. Groundwater carrying phosphorus upwells at springs which discharge into the mainstem lower Portneuf, and segments downstream of this input have elevated P concentrations relative to upstream segments. We are investigating the distribution and abundance of Azolla filiculoides in relation to nutrient stoichiometry and habitat characteristics. We hypothesized that Azolla distribution and abundance would be driven by N:P stoichiometry. We monitored populations, habitat characteristics, and sampled stream margins for nutrients. Analysis included multivariate model selection and is ongoing. Our results indicate phosphorus likely influences Azolla’s distribution between and within upstream and downstream segments. Azolla was absent at sites upstream of P-enriched spring inputs (N:P > 15:1) and was present at most sites downstream (N:P < 15:1). Results for TP and presence/absence were consistent with previous studies describing a P threshold for Azolla and the advantages of N fixation. Within the downstream segment, we also observed differences in Azolla abundance between spring and mainstem sites. We detected an unexpected negative association with DOC which we are investigating further. We hope these results may aid in understanding Azolla’s ecology and provide information to support potential future use as a sensitive bioindicator responsive to shifts in nutrient stoichiometry occurring in this river.

Nina Keck (Primary Presenter/Author), Idaho State University , ninakeck@isu.edu;

Colden Baxter (Co-Presenter/Co-Author), Idaho State University , baxtcold@isu.edu;

Kathleen Lohse (Co-Presenter/Co-Author), Idaho State University , klohse@isu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

RESEARCH THE UTILIZATION OF IRRIGATION SYSTEM INTO INTEGRATED FRAMING AT NAXAITHONG DISTRICT, VIENTIANE CAPITAL CITY. Abstract The development of a fish farming system that uses modern techniques to increase fish production is still very much needed in Laos as well as in the countries downstream of the Mekong River to guarantee food from production to consumers; Water management in the irrigation supply area must use new techniques that are used in fish farming and reduce production costs. Therefore, this research study is not only a report to be published in the journal on the results of the efficient and effective use of water resources in the irrigated, also a summary of the progress of the research conducted in the strategy of reducing the effects of climate change, adaptation, and resilience in agricultural production in Vientiane Plain on sustainable use of water resources to study implementation of strategies and policies into the integrated fish farming system to increase productivity as well as guarantee. In terms of food and income generation for farmer families, empowering producers, reducing the cost of production at the farm level, to mediate and solve the effects of changes in the environment, and weather that affect the production of fish. This research has gathered technical and scientific data from many relevant fields both domestically and abroad, especially in the LMB countries. This research will be a supporting reference for stakeholder, researchers, farmers, strategy, and policy makers for the development of aquaculture, energy, processing industry, and socio-economic development safely and sustainably. Keywords: Aquaculture, livestock, integrated farm, environment, socio- economic, climate change, adaptation, and resilience.

kommaly onxaivieng (POC,Primary Presenter), Department of Livestock and Fisheries , kommaly_2016@yahoo.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

LONG-TERM MONITORING REVEALS TEMPORAL CHANGES AND ENVIRONMENTAL IMPACTS ON BENTHIC MACROINVERTEBRATE COMMUNITIES AT BUFFALO NATIONAL RIVER, ARKANSAS The Buffalo National River is the first nationally protected riverway in the United States. It flows through the lower Ozark Plateau in northwest Arkansas and is the largest undammed river in the region. The Heartland Inventory and Monitoring Network (HTLN) of the National Park Service (NPS) began surveying benthic macroinvertebrate communities and collecting habitat and water quality data throughout the river and its tributaries in 2005. HTLN’s primary initiative is to identify the status of environmental integrity and trends in the benthic invertebrate community through time. While diversity and richness metrics have remained steady over the past 18 years of sampling, abundance for several taxa has changed drastically in that time with one notable taxon, Epoerus (Heptageniidae), remaining absent from Buffalo River collections since 2009. Preliminary statistical results show several water quality and habitat variables, including dissolved oxygen, temperature, conductivity, pH, substrate size, periphyton density, depth, velocity and watershed size are driving community composition. Further analyses are ongoing, and we expect that yearly precipitation has a profound impact on taxa abundance throughout most of the river. Insights from our long-term monitoring efforts will be indispensable for future management of this free-flowing river that, while partially protected within the national park, remains vulnerable to climate change and land use impacts within its watershed outside national park boundaries. Furthermore, we hope that by identifying the severity of various anthropogenic impacts on the benthic communities in the Buffalo River, we can facilitate best practices to preserve the biota of America’s first national river.

Cameron Cheri (Primary Presenter/Author), National Park Service , cameron.r.cheri@gmail.com;

Hope Dodd (Co-Presenter/Co-Author), National Park Service , Hope_Dodd@nps.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Long-Term Spatiotemporal Analysis of Lake Surface Water for Southeast Asia based on Global Surface Water Dataset Southeast Asia (SEA) hosts a large number of lakes that are crucial for providing essential ecosystem services such as water supply, agriculture, tourism, and recreation. Both direct and indirect factors, such as anthropogenic activities and climate variability and change, have had severe impacts on lakes’ surface water and their extent. This research aims to monitor change in lake surface water areas across the whole SEA by delineating and analyzing multi-resolution long-term satellite imagery. A methodology has been set up to track and delineate surface water areas over more than 20 years using Landsat-derived datasets. Map generalization methods were applied to ensure spatial and temporal consistency of data. The results include a seamless lake surface water extent dataset that contains time series of the 663 lakes with an area of at least 1 km2. Preliminary results reveal spatial and temporal patterns of surface water extent dynamics, essential for understanding the relative impacts of changing climate and land uses.

Tatsaneewan Phoesri (Primary Presenter/Author), Asian Institute of Technology , phoesri@gmail.com;

Salvatore G.P Virdis (Co-Presenter/Co-Author), Asian Institute of Technology , virdis@ait.asia;

Nitin K. Tripathi (Co-Presenter/Co-Author), Asian Institute of Technology , nitinkt@ait.ac.th;

Sangam Shrestha (Co-Presenter/Co-Author), Asian Institute of Technology , sangam@ait.asia;

Bachisio Mario Padeda (Co-Presenter/Co-Author), Università degli Studi di Sassari , bmpadedda@uniss.it;

Pratyush Kumar Das (Co-Presenter/Co-Author), Asian Institute of Technology , st120520@ait.asia;

Siwat Kongwarakom (Co-Presenter/Co-Author), Asian Institute of Technology , siwatk@ait.ac.th;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Relationship Between Fecal Indicator Bacteria and Salinity in Freshwater Across the United States Increasing levels of bacteria and rising freshwater salinity are both primary contributors to water quality degradation in the United States, and there might be a link between them. E. coli is widely used as a fecal indicator bacteria (FIB) to assess the presence of pathogens in freshwater, but their survival declines in brackish or marine waters. Recent research observed positive correlations between salts and FIB in watersheds of southwest Virginia and laboratory experiments found increasing salinity increased E. coli persistence along the freshwater salinity gradient. It remains unknown whether increases in salinity results in greater FIB concentrations and impairment broadly across watersheds with different landcovers and climate conditions. Our objective is to determine whether there are positive relationships between salinity and two FIB across the US. We collected water quality data from the National Water Quality Monitoring Council (NWQMC) across the continental US for 43 years (from 1980 to 2023). Watershed attributes were calculated using DEM data from USGS, while corresponding landcover information was extracted from NLCD. Our analysis reveals that as salinity increases within the freshwater range, there is a corresponding rise in FIB across the US, but that relationship is altered by landcover. This work suggests that freshwater salinization could exacerbate bacteria impairments and associated health risks.

Umme Fatema Piu (Primary Presenter/Author), Virginia Polytechnic Institute and State University , fatemapiu@vt.edu;

Stephen DeVilbiss (Co-Presenter/Co-Author), U.S. Geological Survey (USGS) , sdevilbiss@usgs.gov;

Brian Badgley (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University , badgley@vt.edu;

Meredith Steele (Co-Presenter/Co-Author), Virginia Polytechnic Institute and State University , steelem@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

ASSESSING TERRESTRIAL AND AQUATIC RESOURCE QUALITY AND DYNAMICS IN STREAMS ACROSS BIOMES We analyzed the carbon-to-nitrogen ratio (C:N) and high-frequency sensor proxies of different resources available to stream consumers to explore ecosystem energetic differences across biomes using data from NEON (National Ecological Observatory Network). One site, Martha Creek, WA (MART), is in a temperate rainforest containing well-drained, old-growth coniferous forests. The other site, Kings Creek, KS (KING), is a tallgrass prairie stream surrounded by agriculture with intermittent flow and seasonal dry periods. Both streams had similar periphyton C:N ratios (median = 9, 13 at MART, KING), while terrestrial litter resource quality was lower in MART than KING (median = 115 and 42, respectively) and lower quality (higher C:N) than periphyton in both streams. Further research will integrate water quality and sensor data at MART, KING, and three additional sites for further exploration of patterns across biomes: a temperate deciduous forest stream (Walker Branch, TN), a Rocky Mountain stream (Como Creek, CO), and a boreal stream (Caribou Creek, AK). We are compiling water quality nutrient data to compare with the terrestrial and algal nutrient content to potentially link resource input(s) with overall aquatic chemistry. Resource C:N and water quality data will be integrated with high-frequency sensor measurements of chlorophyll (stream algal proxy) and fluorescent dissolved organic matter (terrestrial proxy), and stream discharge to quantify seasonal and flow-driven changes in resource quantity and quality. Integration of resources, water quality, and metabolism estimates across these five sites will aid in the assessment of food web structure drivers.

Allyson N. Kaelin (Primary Presenter/Author,Co-Presenter/Co-Author), Virginia Tech , allysonk@vt.edu;

Caroline M. Brickner (Co-Presenter/Co-Author), Virginia Tech , carolineb27@vt.edu;

Sarah F. Masters (Co-Presenter/Co-Author), Virginia Tech , smasters02@vt.edu;

Tiffany N. Meadows (Co-Presenter/Co-Author), Virginia Tech , tiffanymeadows@vt.edu;

Evelyn L. Dana (Co-Presenter/Co-Author), Virginia Tech , evelyndana@vt.edu;

Isabella Z. Korobow-Velez (Co-Presenter/Co-Author), Virginia Tech , ikorobow21@vt.edu;

Jared A. Rasmussen (Co-Presenter/Co-Author), Virginia Tech , jaredras26@vt.edu;

Peyton W. Rowe (Co-Presenter/Co-Author), Virginia Tech , pwrowe02@vt.edu;

Erin R. Hotchkiss (Co-Presenter/Co-Author), Virginia Tech , ehotchkiss@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Ecological Mechanisms Associated with Fish Species Discharge Relationships in Rivers are Scale Dependent Riverine flow alterations represent an increasing threat to global freshwater fish diversity. Species-discharge relationships (SDR) are used to forecast fish diversity responses to changes in discharge, but they are scale-dependent and likely related to multiple community ecology mechanisms. Possible mechanisms for SDRs are differences in evenness of fish abundances among sampling locations (SAD effects), the number of individuals collected during sampling (N effects), and the degree of within-species aggregation at sampling locations (agg effects). Here we apply traditional linear models to estimate SDRs as well as the Measurement of Biodiversity (MoB) framework to investigate how ecological mechanisms drive the formation of SDR for stream fishes collected using 1,020 seine hauls across reach (102 m extent), segment (103 m), and stream (104 m) spatial scales in the Colorado River Basin of Texas. We found evidence of SDRs at the stream and segment scales that were driven by positive SAD effects, but lack of an SDR at the reach scale was driven by SAD and N effects operating in opposing directions. Our work emphasizes the scale-dependent nature of mechanisms underpinning SDRs, suggests the need for scaling up biodiversity inventories beyond reaches to include segments and streams, and reveals that a major driver of species richness loss caused by dewatering might be the emergence of dominance by a small number of species where water abstraction and diversion are greatest.

Rebecca Mangold (Primary Presenter/Author), Texas A&M University , rebecca.mangold@tamu.edu;

Lindsey Elkins (Co-Presenter/Co-Author), Texas Parks and Wildlife , Lindsey.Elkins@tpwd.texas.gov;

Christina Saltus (Co-Presenter/Co-Author), US Army Engineer Research and Development Center , christina.l.saltus@erdc.dren.mil ;

Richard Johansen (Co-Presenter/Co-Author), US Army Engineer Research and Development Center , richard.a.johansen@erdc.dren.mil;

Joshuah Perkin (Co-Presenter/Co-Author), Texas A&M University , jperkin@tamu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Using ICON Science to Understand River Biogeochemistry at a Continental Scale River corridors exert a large influence in regulating Earth’s climate through the microbial conversion of organic matter into carbon dioxide. The hyporheic zone, an essential site of biogeochemical processing within river corridors, contributes anywhere from minimal amounts (4%) to nearly all (96%) of this respiration. There remains a lack of data-driven and mechanistic models to predict this variability, leaving a gap in our ability to predict changes across local and global scales. We address this gap by leveraging crowdsourced science, facilitated by the collaborative efforts of the Worldwide Hydrobiogeochemical Observation Network for Dynamic River Systems (WHONDRS) consortium and applying ICON (Integrated, Coordinated, Open, and Networked) science principles to provide mutual benefit and transferable knowledge. Input collected before the study commenced ensured that the data met a wide variety of needs. Following this, a machine learning (ML) model was constructed using laboratory-measured sediment respiration and metadata observations from collaborators to inform future sampling decisions across the contiguous United States. After 18 iterations between model-guided data generation and testing, the ML model achieved 80% predictive skill for sediment respiration rates. Broadly, organic matter properties as well as physical parameters such as sediment size and land use indices, have emerged as the most important inputs to the ML model. Our engagement process and improvements in model prediction facilitates effective communication of outcomes and refines our approach to make our data and models FAIR (findable, accessible, interoperable and reusable) for a wide spectrum of stakeholders, including scientists, educators, and policymakers.

Dillman Delgado (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , dillman.delgadoparedes@pnnl.gov;

Maggi Laan (Primary Presenter/Author), Pacific Northwest National Laboratory , maggi.laan@pnnl.gov;

Vanessa Garayburu-Caruso (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , vanessa.garayburu-caruso@pnnl.gov;

Lupita Renteria (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , lupita.renteria@pnnl.gov;

Sophia McKever (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , sophia.mckever@pnnl.gov;

Brieanne Forbes (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , brieanne.forbes@pnnl.gov;

Amy Goldman (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , amy.goldman@pnnl.gov;

Stefan Gary (Co-Presenter/Co-Author), Parallel Works , sfgary@parallelworks.com;

Em Rexer (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , emily.rexer@pnnl.gov;

Timothy Scheibe (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , tim.scheibe@pnnl.gov;

James Stegen (Co-Presenter/Co-Author), Pacific Northwest National Laboratory , james.stegen@pnnl.gov;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

INSIGHTS INTO SPATIAL VARIATION IN ANATOXIN PRODUCTION WITHIN AND ACROSS RIVER NETWORKS AND LAKES IN CALIFORNIA, USA Proliferations of anatoxin-producing benthic cyanobacteria, notably Microcoleus, threaten aquatic ecosystems and public health. While our understanding of within-river temporal variation in anatoxin concentrations has improved, accurately predicting locations where anatoxins are produced remains a significant challenge. We used data from the California Environmental Data Exchange Network (CEDEN) to analyze anatoxin detections in 236 lake and 315 river samples to explore the influence of environmental factors. Total anatoxin concentrations were primarily measured using ELISA (70%), with fewer measured by LC-MS/MS (22%) or RBA (8%). Collection methods varied; lakes were primarily sampled using water grabs (75%) instead of algal mat or scum samples (25%). In contrast, rivers were predominantly sampled using benthic or surface algal mats (78%) instead of water grabs (22%). Across all sample types, lake samples had a lower positive detection rate (20%) than river samples (40%). Median concentrations among lake samples above detection were 1.05 µg/L (range: 0.11 to 3.89 µg/L) with the highest concentration occurring in a scum sample from Big Bear Lake. Median concentrations among river samples above detection were 1.58 µg/L (range:0.13 to 7709.1 µg/L) with the highest concentration occurring in a benthic algal mat from the Russian River. Further investigation of the relative influence of river and watershed characteristics on spatial variation in detected anatoxins will inform a 2024 spatial sampling campaign. Improving our understanding of anatoxin production in rivers can help inform monitoring strategies to mitigate ecological and public health risks.

Andrea Garcia Jimenez (Primary Presenter/Author), University of Nevada-Reno , agarciajimenez@nevada.unr.edu;

Taryn Elliott (Co-Presenter/Co-Author), University of Nevada, Reno , taryne@unr.edu;

Rosalina Stancheva Christova (Co-Presenter/Co-Author), George Mason University , rchris13@gmu.edu;

Laurel Genzoli (Co-Presenter/Co-Author), University of Montana , laurel.genzoli@umontana.edu;

Michael Thomas (Co-Presenter/Co-Author), California State Water Resources Control Board , Michael.Thomas@waterboards.ca.gov;

Rich Fadness (Co-Presenter/Co-Author), California State Water Resources Control Board , Rich.Fadness@waterboards.ca.gov;

Ramesh Goel (Co-Presenter/Co-Author), University of Utah , ram.goel@utah.edu;

Robert Shriver (Co-Presenter/Co-Author), University of Nevada, Reno , rshriver@unr.edu;

Joanna Blaszczak (Co-Presenter/Co-Author), University of Nevada, Reno , jblaszczak@unr.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Species Abundance and Stream Food Web Structure Across Biomes What determines stream food web structures and interactions across terrestrial biomes? We are addressing this question with National Ecological Observatory Network (NEON) data, published diets, and analyses in R. We extracted data from two streams over 4 years (2019–2022): Martha Creek, WA (MART) in a temperate rainforest climate and drains old-growth coniferous forest and King Creek, KS (KING) in a tallgrass prairie ecoregion, drains prairie, agriculture and pasture, and has intermittent flow with seasonal dry periods. For these sites, we analyzed the abundance and food web roles of aquatic primary producers, macroinvertebrates, and fish. MART and KING each contain nine primary producer species, eight of which are unique to each site. We used growth forms of primary producers (submerged, emergent) to relate primary producers to published diet information for macroinvertebrates and fish. We found higher invertebrate species richness at MART over KING (239 and 152, respectively); there were 1 fish species at MART and 20 at KING. Despite different terrestrial biomes surrounding MART and KING, there were similar percentages of macroinvertebrate herbivores (17%, 15%) and detritivores (17%, 12%). Ongoing work will include data on year-to-year community turnover at each site, estimate functional group biomass at different trophic levels, assess food web structure in the context of basal resource availability, and integrate food web data from three other stream sites to assess drivers of food web dynamics across biomes: Walker Branch, TN, in a temperate deciduous forest; Como Creek, CO, in the Rocky Mountains; and Caribou Creek, AK, a boreal stream.

Evelyn L. Dana (Primary Presenter/Author,Co-Presenter/Co-Author), Virginia Tech , evelyndana@vt.edu;

Isabella Z. Korobow-Velez (Co-Presenter/Co-Author), Virginia Tech , ikorobow21@vt.edu;

Peyton W. Rowe (Co-Presenter/Co-Author), Virginia Tech , pwrowe02@vt.edu;

Jared A. Rasmussen (Co-Presenter/Co-Author), Virginia Tech , jaredras26@vt.edu;

Caroline M. Brickner (Co-Presenter/Co-Author), Virginia Tech , carolineb27@vt.edu;

Allyson N. Kaelin (Co-Presenter/Co-Author), Virginia Tech , allysonk@vt.edu;

Sarah F. Masters (Co-Presenter/Co-Author), Virginia Tech , smasters02@vt.edu;

Tiffany N. Meadows (Co-Presenter/Co-Author), Virginia Tech , tiffanymeadows@vt.edu;

Erin R. Hotchkiss (Co-Presenter/Co-Author), Virginia Tech , ehotchkiss@vt.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Taxonomic and functional assemblage turnover thresholds in response to hydrologic alteration and temperature across flow regimes Alterations to stream hydrology and temperature are occurring at accelerating rates by the combined pressures of human water needs and climate change. Quantifying critical environmental thresholds where assemblages are predicted to turnover and potentially destabilize ecosystem integrity is integral for targeted management of stream alteration. We will identify environmental thresholds where the taxonomic and functional composition of freshwater fish and aquatic insect assemblages are predicted to turnover within and across flow regimes (runoff, intermittent, and groundwater) of Interior Highlands (Arkansas, Missouri, and Oklahoma), USA. We collated over 100,000 occurrence records encompassing 614 aquatic insect taxa and 250 fish species from aquatic surveys and life history data incorporating morphological, phenological, reproductive, trophic, thermal, habitat, and dispersal characteristics. We identified an average insect richness across sites of 33.6 (range 1 – 154) and an average functional diversity, as estimated by functional dispersion, of 0.149 (range 0 – 0.224). Average fish richness was 16 (range 1 – 102) and functional diversity was 0.168 (range 0 – 0.256). We found no diversity quantity difference among flow regimes in both insects and fish. We will estimate functional composition turnover by first developing life history guilds using hierarchical cluster analysis. Finally, we will use gradient forest modeling to identify taxonomic and functional assemblage turnover using stream condition alteration thresholds within and across flow regimes. Identifying stream alteration-ecology relationships can help inform stream management efforts to minimize the loss of ecosystem integrity while balancing the inevitable increase in stream alteration from human water needs and climate change.

Chloe Moore (Primary Presenter/Author), Arkansas Cooperative Fish and Wildlife Research Unit, Department of Biological Sciences, University of Arkansas , chloe9mo@gmail.com;

Daniel Magoulick (Co-Presenter/Co-Author), Arkansas Cooperative Fish and Wildlife Research Unit, University of Arkansas , danmag@uark.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Broad-scale patterns of macroinvertebrate food web structure in United States intermittent streams Non-perennial streams are considered the most commonly occurring stream type across the globe. Periodic flow cessation in streams can alter interactions between aquatic and terrestrial habitats, which are important in determining stream food web structure. The cyclical nature of drying and rewetting in intermittent streams can modify food chain length, as well as the dominance of algal vs. detrital energetic pathways. Due to their abundance, aquatic-terrestrial life cycles, and intermediate trophic position, benthic macroinvertebrates serve as model organisms for food web studies in lotic systems. Here, we aim to quantify macroinvertebrate food web structure using stable isotopes from 6 river networks across the United States. The networks have been selected to be representative of the climatic and precipitation gradient across the southern US. Using ?15N and ?13C from basal resource and macroinvertebrate samples we will calculate community-wide metrics for each taxa present, to model food web complexity and resource usage. We expect to see a decrease in food chain length, as well as a greater dependence on terrestrial energy pathways with increased drying.

Kierstyn Higgins (Primary Presenter/Author), The Pennsylvania State University , kth5285@psu.edu;

Albert Ruhi (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley , albert.ruhi@berkeley.edu;

Kyle Leathers (Co-Presenter/Co-Author), University of California Berkeley , kyle_leathers@berkeley.edu;

Rose Mohammadi (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley , rmohammadi@berkeley.edu;

Travis Apgar (Co-Presenter/Co-Author), University of California, Berkeley , travis.apgar@berkeley.edu;

Yang Hong (Co-Presenter/Co-Author), The University of Oklahoma , yanghong@ou.edu;

Carla L. Atkinson (Co-Presenter/Co-Author), The University of Alabama , carla.l.atkinson@ua.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

Chelsea R. Smith (Co-Presenter/Co-Author), The University of Alabama , crsmith5@crimson.ua.edu;

Meryl Mims (Co-Presenter/Co-Author), Virginia Tech , mims@vt.edu;

Sam Silknetter (Co-Presenter/Co-Author), Virginia Tech , silknets@vt.edu;

Daniel Allen (Co-Presenter/Co-Author), The Pennsylvania State University , dca5269@psu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

HIGH, DRY AND OUT IN THE COLD: A CALL FOR COORDINATED RESEARCH ON FREEZING NON-PERENNIAL STREAMS In recent years, there has been a concerted and remarkably successful effort to draw scientific and public attention to the hydrologic, biogeochemical, and ecological role of non-perennial streams. Much of this work has and is being accomplished through a shift towards coordinated and networked efforts spanning across tropical and temperate climates. Several studies have also highlighted the unique hydrology, ecology, and biogeochemistry of freezing non-perennial streams, identifying several unanswered questions about the function and resilience of such systems that experience drying and freezing conditions. However, unlike their temperate counterparts, there has yet to be a proliferation of coordinated or networked studies to synthesize knowledge of non-perennial systems in high-elevation and high-latitude regions. Rather, most studies of freezing stream networks remain focused on singular sites and/or experiments. We seek to catalyze interest in efforts to develop shared hypotheses, methods, technologies, and data curation strategies needed for cross-system synthesis and prediction on non-perennial streams in cold regions experiencing accelerating change.

Joel Singley (Primary Presenter/Author), Roger Williams University , jsingley@rwu.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

INFLUENCE OF FLOW INTERMITTENCY ON LEAF LITTER DECOMPOSITION AND MACROINVERTEBRATE COMMUNITIES IN A GULF COASTAL PLAIN STREAM NETWORK Decomposition and assimilation of leaf litter-derived [C]arbon and [N]itrogen are critical to ecosystem function in forested streams, and these processes vary with flow magnitude. Due to climate change and anthropogenic water extraction, the extent of flow intermittency is increasing, reducing connectivity and altering biotic communities with unknown consequences on organic matter (OM) dynamics. Here, we quantify OM decomposition across an intermittency gradient to assess the impacts of connectivity and macroinvertebrate community composition on decay rates. We conducted benthic Surber sampling of macroinvertebrates in February 2021 and March 2022 from 10 streams across the South Sandy watershed (125 km2), a forested stream network flowing through the Talladega National Forest in central Alabama, USA. Our sites include a spatially distributed network of perennial and intermittent reaches. We then performed an in-situ leaf litter decomposition study from June-July 2023 using 190 Liriodendron tulipifera litter packs across our 10 sites. We periodically collected litter packs to measure decomposition and identify litter-occupying macroinvertebrates. Though we found no difference in the mean litter decomposition rates of intermittent and perennial sites, we found greater variation in sites with intermittent flow (CV = 51.46 and 9.43, respectively). Decomposition was significantly correlated with shredder abundance from 2021-2022 samples (p = 0.01), and the proportion of shredders was greater in perennial sites than in intermittent sites (p = 0.03). Our results show that detrital resource processing is not exclusively flow-limited, but driven by complex biotic and abiotic factors.

Jacob Dorris (Primary Presenter/Author), The University of Alabama , jddorris@crimson.ua.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

Brian Gill (Co-Presenter/Co-Author), School of Natural Resources and the Environment, The University of Arizona , briangill@email.arizona.edu;

Michael Bogan (Co-Presenter/Co-Author), School of Natural Resources and the Environment, The University of Arizona , mbogan@email.arizona.edu;

Chelsea Smith (Co-Presenter/Co-Author), University of Alabama , chelsea.smith@jonesctr.org;

Sarah Kelley (Co-Presenter/Co-Author), The University of Alabama , sgkelley1@gmail.com;

Carla L. Atkinson (Co-Presenter/Co-Author), The University of Alabama , carla.l.atkinson@ua.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Hydrologic variables, rather than land management practices, exert a profound influence on aquatic macroinvertebrate communities. Non-perennial streams stand as pivotal ecosystems, harboring a diverse array of macroinvertebrate species. These organisms assume multifaceted roles within their habitats—integral components of the food web, bioindicators reflecting ecosystem quality, and significant contributors to the natural biodiversity of these systems. In our exploration of the interplay between hydrologic regime and land management practices on macroinvertebrate communities, we conducted comprehensive sampling along the Kings Creek, KS watershed, which courses through the Konza Prairie Long-Term Ecological Research (LTER) site. The Konza Prairie LTER exhibits varying sub-watershed land management practices contingent upon grazer type and burn status. Over a span of two years, we collected benthic and edge macroinvertebrate samples from 10 sites across the watershed. Post-collection, we subjected the empirical data to analysis, utilizing both Excel and R. Taxonomic identification was pursued to the lowest practical taxonomic unit. We focused on the impacts of the year of sampling, the presence of grazers (bison, cattle, or none), flow dynamics (intermittent or perennial), and burn schedule (ranging from 0 to 4 years, or no burning) on two diversity metrics—taxonomic richness and Shannon’s diversity index. The outcomes of this analysis were expressed visually through scatterplots. In our discernment, aquatic invertebrate communities displayed variations in response to flow regime yet remained unaffected by land management practices. Our discernments propose that the influences of the flow regime eclipse any potential impacts of grazers or burn status on aquatic macroinvertebrate communities.

Olivia Tow (Primary Presenter/Author), University of Oklahoma , towolivia0900@gmail.com;

Megan Malish (Co-Presenter/Co-Author), University of Oklahoma , megan.malish@ou.edu;

Daniel Allen (Co-Presenter/Co-Author), Penn State , daniel.c.allen@psu.edu;

Thomas Neeson (Co-Presenter/Co-Author), University of Oklahoma , neeson@ou.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Quantifying Movement and Storage of Anthropogenic Materials in Urban Restored Floodplains in Charlotte, North Carolina, USA. Garbology is a new frontier of study worldwide, and can be approached using multiple scientific disciplines across a diversity of ecosystems. While many researchers are focused on the role of microplastics in the oceans, there is less literature on the macro-trash pollution in freshwater ecosystems. The goal of this study is to determine the main driving landscape factors that contribute to the storage of anthropogenic debris on urban floodplains. Three transects along 2 streams of varying sizes in the Charlotte Metropolitan area are being sampled bi-monthly from February - August 2024. Collected trash is sorted into material categories of Plastic, Paper, Metal, Glass, and Other, in partial accordance with the EPA’s Environmental Trash Assessment Protocols (ETAP). For each category, an individual item count, total volume (L) and total weight (Kg) is recorded. As trash is being collected, it will be noted if it was found either buried in sediments, freestanding, or caught in vegetation. Trash variables will be analyzed using general linear models to test for correlation between 17 proposed landscape factors representing physical, human, and business parameters. Each factor will be measured for correlation at three landscape scales, 200m, 2km, and 5km from the pour point of the selected stream. Results will be able to inform the local public and government about targeted plans of action that can be taken to reduce debris pollution in urban restored floodplains.

Sophie Barnett (Primary Presenter/Author), University of North Carolina at Charlotte , sophie8barnett@gmail.com;

Sandra Clinton (Co-Presenter/Co-Author), Department of Geography and Earth Sciences, University of North Carolina Charlotte , sclinto1@uncc.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

SPATIAL DISTRIBUTION OF MICROPLASTICS IN AN URBAN RIVER The production and disposal of plastic have generated accelerating global accumulations of litter since the mid-1900s. Rivers are key sources of microplastics (i.e., particles 1 µm - 5 mm) to oceans, but the distribution of microplastics within river habitats is less well studied. We measured microplastic abundance in 3 habitats (surface water, water column, benthic zone) at 4 sites in the North Branch Chicago River watershed. We used peroxide oxidation, visual counting, and polymer identification to quantify microplastics. We predicted deposition as suspended particles would generate the highest number of microplastic particles at the benthic zone relative to the surface water and water column habitats. By polymer type, we predicted stratification by density, with heavier polymer types found more in the water column and benthic zone relative to the surface. Across the four study sites, we predicted a higher concentration of microplastics would occur downstream, reflecting instream breakdown of macroplastic and movement of suspended microplastics with the river current. Overall, microplastics are likely to show high variation among ecosystem compartments, both by abundance and composition. Assessments of habitat-specific distribution data are needed to better quantify microplastic movement and retention. These data will help place stream microplastic dynamics within the broader framework of global plastic budgets.

Jaden Nguyen (Primary Presenter/Author), Loyola University Chicago , nguyenjaden2002@gmail.com;

Olivia Schaul (Co-Presenter/Co-Author), Loyola University Chicago , oschaul@luc.edu;

Bailey Schwenk (Co-Presenter/Co-Author), Loyola University Chicago , bschwenk@luc.edu;

Elizabeth Kazmierczak (Co-Presenter/Co-Author), Loyola University Chicago , ekaz0103@gmail.com;

Fritz Petersen (Co-Presenter/Co-Author), Case Western Reserve University , fxp120@case.edu;

Richard Lammers (Co-Presenter/Co-Author), University of New Hampshire , Richard.Lammers@unh.edu;

Emily Lever (Co-Presenter/Co-Author), University of New Hampshire , Emily.Lever@unh.edu;

Shan Zuidema (Co-Presenter/Co-Author), University of New Hampshire , shan.zuidema@unh.edu;

Xia Zhu (Co-Presenter/Co-Author), University of Toronto , alicexia.zhu@mail.utoronto.ca;

Jacob Haney (Co-Presenter/Co-Author), University of Toronto , jacob.haney@utoronto.ca;

Chelsea Rochman (Co-Presenter/Co-Author), University of Toronto , chelsearochman@gmail.com;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire , wil.wollheim@unh.edu;

Timothy Hoellein (Co-Presenter/Co-Author), Loyola University Chicago , thoellein@luc.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

STORM-MEDIATED TRANSPORT OF MICROPLASTIC IN AN URBAN WATERSHED Plastic pollution is persistent, and pervasive at a global scale. Microplastics (particles 1 µm - 5 mm) are a focus of research, given their abundance, mobility, and capacity for ingestion by biota. Rivers export microplastics to oceans and periods of flooding are likely a critical component of their movement downstream. However, measurements of microplastics during floods are uncommon. We quantified microplastics before, during, and after storm events at 4 sites throughout the North Branch Chicago River, USA. Before and after the storm events, we collected surface, water column, and benthic water samples. During storms, water column samples were collected with automated samplers. We used peroxide oxidation, visual characterization, and Fourier-transform infrared spectroscopy (FTIR) for microplastic identification. We predict microplastic concentration and flux will be highest on the rising hydrograph limbs of storm hydrographs (i.e., the ‘first flush’ pattern) relative to other phases of the storms. We also expect higher-density polymers will be found at high discharge relative to low discharge. Last, we expect total microplastic flux from storms will be positively related to storm intensity, and flux will be highest at the most downstream site. Results will provide a more comprehensive understanding of the distribution and movement of microplastics within freshwater ecosystems. Data will contribute to improved models of the plastic cycle at the watershed scale, supporting efforts to mitigate and prevent plastic pollution in aquatic ecosystems.

Olivia Schaul (Primary Presenter/Author), Loyola University Chicago , oschaul@luc.edu;

Jaden Nguyen (Co-Presenter/Co-Author), Loyola University Chicago , nguyenjaden2002@gmail.com;

Bailey Schwenk (Co-Presenter/Co-Author), Loyola University Chicago , bschwenk@luc.edu;

Elizabeth Kazmierczak (Co-Presenter/Co-Author), Loyola University Chicago , ekaz0103@gmail.com;

Fritz Petersen (Co-Presenter/Co-Author), Case Western Reserve University , fxp120@case.edu;

Emily Lever (Co-Presenter/Co-Author), University of New Hampshire , Emily.Lever@unh.edu;

Shan Zuidema (Co-Presenter/Co-Author), University of New Hampshire , shan.zuidema@unh.edu;

Xia Zhu (Co-Presenter/Co-Author), University of Toronto , alicexia.zhu@mail.utoronto.ca;

Jacob Haney (Co-Presenter/Co-Author), University of Toronto , jacob.haney@utoronto.ca;

Chelsea Rochman (Co-Presenter/Co-Author), University of Toronto , chelsearochman@gmail.com;

Wilfred M. Wollheim (Co-Presenter/Co-Author), University of New Hampshire , wil.wollheim@unh.edu;

Timothy Hoellein (Co-Presenter/Co-Author), Loyola University Chicago , thoellein@luc.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

SEASONAL MICROPLASTIC ABUNDANCE AND COMPOSITION IN RIVER BIOTA LINKED WITH LAND USE AND SPECIES TRAITS Microplastics (MPs; < 5 mm) are a pervasive contaminant in freshwater habitats and biota worldwide. Terrestrial-aquatic subsidy exchanges can move anthropogenic litter into aquatic habitats where they may fragment into MPs and enter the food web. We sought to understand the importance of watershed land use and landcover (e.g., percent urban; LULC) and river tributaries in connection to the sources, abundances, and compositions of MPs entering a freshwater lake. We investigated 1) if seasonal MP concentrations in freshwater biota vary with species traits across a LULC gradient, and 2) the potential relationships between MP patterns in biota and their habitats. Eight river tributaries differing in dominant LULC were sampled seasonally for MPs in river surface water, benthic sediments, fish, and macroinvertebrates. Preliminary results from three of the eight rivers sampled indicated that MP contamination was present in river habitat, fish, and macroinvertebrate samples, with fibers contributing approx. 97-100% of all MP particles. Surface water samples contained an average of 16 particles/sample. Eighty-five percent of fish individuals across functional feeding groups (e.g., detritivore, zoobenthivore) contained an average of approximately 13 MPs/fish. There was a positive relationship between MP concentrations and fish trophic fraction, suggesting that MPs may move through the food web due to species trophic traits (X2= 14.18, P= 0.001). This study is anticipated to further reveal potential links of MP pollution to environmental variables (e.g., season, LULC). This will inform targeted MP mitigation strategies for aquatic resources and increase our knowledge of the ecological consequences of MP pollution.

Alexandra Brown (Primary Presenter/Author), California State University Bakersfield , abrown84@csub.edu;

Rae McNeish (Co-Presenter/Co-Author), California State University Bakersfield , rae.mcneish@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

THE EFFECT OF URBANIZATION ON GUPPY'S FUNCTIONAL TRAITS Urbanization and the introduction of invasive species to freshwater systems have been rapidly expanding. Yet there is limited understanding of how invasive organisms adapt and survive to urban streams. Urban stream ecosystems are characterized by high loads of nitrogen and phosphorus. Researchers hypothesized that invasive species will thrive in systems with high nutrient availability if they can present adaptive responses of nutrient assimilation that capitalize on that nutrient excess. However, the effects of urbanization on morphological structures related to assimilation, such as gut length, remain understudied in freshwater fish. Natural observations have showed that under poor-quality diets, fish often present longer guts. The opposite is true for fish consuming protein-rich food (e.g. macroinvertebrates). To explore the influences of urbanization on gut length we will use the Trinidadian guppy, an invasive species introduced around the globe and well known for their rapid evolution. Our main objective is to analyze the influences of different levels of urbanization on the allometric relationships between gut length and body size of guppies. We hypothesize that if invasive species are adapting and taking advantage of the nutrient-rich resources present in urban environments, then the energy spent on the production of gastrointestinal tissues will be reduced. I predict that fish under high urbanization will show shorter gut lengths than fish under low urbanization sites. Thus, I expect to find a hypoallometric relationship (a<1) between gut length and body size for fish under high urbanization.

Ellie Butkovich (Primary Presenter/Author), Cornell University , efb85@cornell.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

THE QUEST PROJECT: INTEGRATING CATCHMENT EXPANSION-CONTRACTION DYNAMICS INTO CROSS-CONTINENTAL HYDRO-BIOGEOCHEMICAL PREDICTIONS The QuEST (Quantifying Ecosystem exports across Space and Time) Project seeks to expand our understanding of hydrologic and biogeochemical change in headwater networks that dynamically expand and contract. Headwater stream networks comprise ~80% of all river miles on Earth and are important “reactors” due to their relatively large reactive streambed surface area compared to the volume of water and materials they transport. We currently lack a predictive understanding of how climate-mediated changes in patterns of stream network expansion and contraction in response to shifting precipitation regimes interact with material processing within headwaters and change material export to larger rivers. Our approach integrates hydrologic modeling with complementary hydrologic and biogeochemical observations within five watersheds spanning the United States’ cross-continental aridity gradient. Specific activities include: 1) integrating empirical data and hydrological models to evaluate surface and subsurface flow contributions to the flowing structure of the stream network, 2) using comparative ecohydrologic metrics from repeated “snapshot” campaigns of catchment-wide stream chemistry to evaluate how small headwater tributaries impose variability observed at coarser spatial scaless, and 3) deploying an array of high-frequency water quality sensors spatially distributed within each catchment to capture how stream network expansion and contraction dynamics change carbon, nutrient, and material exports across climatic conditions. As data collection occurs, we are also analyzing existing long-term datasets to address our central questions and characterize our focal watersheds. We will present the project’s structure and goals, as well as preliminary results from initial field campaigns and ongoing analyses.

Joanna Blaszczak (Primary Presenter/Author), University of Nevada, Reno , jblaszczak@unr.edu;

Alex Webster (Co-Presenter/Co-Author), University of New Mexico , awebster2@unm.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama , ashogren@ua.edu;

Mengye Chen (Co-Presenter/Co-Author), University of Oklahoma , mchen15@ou.edu;

Yang Hong (Co-Presenter/Co-Author), The University of Oklahoma , yanghong@ou.edu;

Shannon Speir (Co-Presenter/Co-Author), University of Arkansas , slspeir@uark.edu;

Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire , adam.wymore@unh.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Information Flow in Watersheds Using High-Frequency Sensor Networks Landscape attributes can cause certain river reaches to disproportionately contribute to surface water and nutrient budgets compared to others. Identifying such reaches can be difficult due to multiple converging tributaries and time lags between inputs of nutrients and potential in-reach transformations. The role of antecedent conditions may also influence the spatial and temporal interactions between runoff and solute fluxes. High-frequency sensor networks within a watershed provide a means for collecting 15-minute data on the concentrations (C) of nutrients (e.g., nitrate) and hydrologic tracers (e.g., specific conductance) alongside river discharge (Q) in a nested watershed design. Here, we apply information theory metrics to 10-years of high-frequency sensor data records of Q and C from the Lamprey River Hydrological Observatory in New Hampshire, USA from four sites spanning river order and landuse. We use this dataset to describe dominant mechanisms, spatial “hot spots”, and temporal “hot moments”, that lead to enhanced predictability of CQ relationships across a watershed. We perform this analysis both annually and seasonally to characterize variability in these hot spots and hot moments. Overall, we hypothesize that the tributary Q term will provide more information to mainstem CQ dynamics than the C term, and that sites will display variability in information flow from tributary to mainstem based on landuse. Specifically the largest tributary will transfer the most information to mainstem Q dynamics and the urban tributary will transfer the most information to mainstem C dynamics.

Desneiges Murray (Primary Presenter/Author), University of New Hampshire , desneiges.murray@unh.edu;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire , bill.mcdowell@unh.edu;

Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire , adam.wymore@unh.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

METABOLIC RESPONSES OF A TROPICAL STREAM TO DROUGHT AND HURRICANE DISTURBANCES Droughts and hurricanes are increasing in severity and frequency in tropical rainforest ecosystems due to climate change. These disturbance events alter the quantity and variety of organic matter (OM) inputs entering tropical freshwater streams, which are subsequently metabolized by microbes and macroinvertebrates. We investigate how climatic events affect metabolic responses (i.e., gross primary production (GPP) and ecosystem respiration (ER)) to disturbance-initiated organic matter entering streams. This study uses long-term, high-frequency sensor data over multiple years to calculate the metabolic regime of a small headwater stream at the Luquillo Long-Term Ecological Research site in Puerto Rico as a way to identify the effects of droughts and hurricanes in a tropical freshwater ecosystem. We expect droughts to cause a tropical stream to become increasingly heterotrophic because ER will increase and GPP will decrease due to the combination of increased allochthonous OM as a result of physiological stress to riparian vegetation and decreased water flow. Conversely, we expect hurricanes will cause a stream to become less heterotrophic because ER will decrease and GPP will increase due to the combination of increased scouring and discharge overpowering the increased allochthonous OM inputs and increased light penetration resulting from the opening canopy. Calculating GPP and ER and analyzing dissolved oxygen trends during and following major disturbances will further our understanding of carbon cycling and whole-ecosystem processes in tropical watersheds in response to hurricanes and droughts-based disturbances.

Alicia Dixon (Primary Presenter/Author), University of New Hampshire , dixon.alicia98@gmail.com;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire , bill.mcdowell@unh.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Concentration-discharge relationships of chlorophyll describe the origin and export of river algae in the Delaware River Basin Benthic and planktonic sources of algae differ in structural and functional patterns and exhibit unique ecological roles in river ecosystems dynamics. Hence, partitioning the contribution of benthic and planktonic sources to phytoplankton fluxes will advance our understanding of algal production and transport in river systems. Here, we examine concentration-discharge (C-Q) relationships of suspended chlorophyll to determine the origin (benthic or planktonic) and mobilization (proximal or distant sources) of river algae during storm events. We aim to relate C-Q responses characterized by hysteresis (HI), flushing (FI), or C-Q slope indices to specific conditions of river size, channel slope, or nutrient availability across the Delaware River Basin (DRB).Our study includes 7 sites across 5 sub-watersheds ranging in size from 141km2 to 17,818km2 with varying structural complexity, land use, and eutrophication degree. Preliminary results show predominantly positive HI (0.199 ± 0.042) and positive FI (0.492 ± 0.051) values in the Schuylkill (4,927 km2), Musconetcong (403km2) and Pennypack (144km2) watersheds, indicating nearby sources that mobilize rapidly. In contrast, the Brandywine River (865km2), characterized by numerous low-head dams and lower nutrient concentrations, exhibits a negative HI (-0.187 ± 0.0295) indicating delayed mobilization of benthic algae. Interestingly, C-Q responses observed in the free-flowing portion of the Delaware River (17,818km2) significantly resemble those of much smaller watersheds, suggesting similar algal dynamics despite their channel size differences. Results from phytoplankton community composition and benthic standing stocks during baseflow conditions provide additional insight to compare phytoplankton origin and transport across these watersheds.

Rachel Leonard (Primary Presenter/Author), Stroud Water Research Center / University of Delaware , rleonard@stroudcenter.org;

Marc Peipoch (Co-Presenter/Co-Author), Stroud Water Research Center , mpeipoch@stroudcenter.org;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Phosphorus concentration and stoichiometry in a tropical rain forest Humid tropical forests play a dominant role in many global biogeochemical cycles, yet long-term records of tropical stream chemistry and nutrient stoichiometry are relatively rare. Here we document the effect of season, storms, and long-term trends on P and N:P in Puerto Rico over a period of 22 years. Phosphorus can limit terrestrial primary productivity in humid tropical forests, since tropical soils are high in iron oxides that bind the P and make it unavailable to plants and downstream ecosystems. Weathering of parent material can increase phosphorous availability in streams, as does African dust from the Sahara in our study region of Puerto Rico and much of the neotropics. Half (interquartile range) of the stream N:P values ranged from 7-34 (median 15), while 50% of the rain N:P values were in the range 3-19 (median 6), indicating that stream nutrient (N versus P) limitation is variable around Redfield N:P of 16:1. Watersheds with higher deposition of Saharan dust exhibit higher concentrations of P and lower N:P in inputs and outputs than watersheds downwind. Stream N:P declines with increasing silica indicating weathering as a source of P as well. We also explore N:P relationships with discharge and stream N and P additions for insight into in-stream dynamics. Phosphorus cycling is more dynamic in this tropical region than previously thought and may be subject to a wide range of biogeochemical controls.

Jody Potter (Primary Presenter/Author), University of New Hampshire , jody.potter@unh.edu;

Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire , adam.wymore@unh.edu;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire , bill.mcdowell@unh.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Dissolved Organic Matter as a Socioecological Tool Urban stream pollution from wastewater, stormwater, nutrient runoff, and trash is a global issue. As urbanization continues, it is important to assess sources of pollution and the impact of mitigation measures, and the distribution of risks and investments across populations. The optical properties of dissolved organic matter (DOM) reflect DOM sources, and therefore can be used as a tool to identify pollutant sources. We combined water sampling and geospatial analysis in Baltimore, Maryland to answer: 1) what urban watershed characterizations influence Baltimore’s DOM quality? And 2) what do these patterns suggest about the sources of poor urban water quality? We sampled surface water at 54 sites within the City of Baltimore and analyzed them for concentrations of nutrients, organic carbon, and DOM quality. DOM quality primarily varied along a gradient from microbially-sourced to humic DOM. The fluorescence index, an indicator of microbially-source DOM expected to be associated with wastewater inputs, was negatively correlated with median household income (R² =0.26, p= <0.0001), and negatively correlated with nutrient best management practice (BMP) density (R²=0.31, p= <0.0001). BMP density was positively correlated with household income (R²= 0.46, p= <0.0001). These results indicate that restoration efforts are disproportionately distributed within Baltimore watersheds, and BMP density may mitigate wastewater inputs to streams, though the mechanism of this effect is unclear. These disproportionalities cause poorer communities to have more impaired waterways.

Alexandra Acevedo (Primary Presenter/Author), Smithsonian Environmental Research Center , alexandra24rose@gmail.com;

Rebecca Hale (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , haler@si.edu;

Carey Pelc (Co-Presenter/Co-Author), Smithsonian Environmental Research Center , pelcc@si.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Effects of Single-Use Plastic Bans on the Abundance and Types of Anthropogenic Litter in southeast Pennsylvania streams Large quantities of plastic and low recycling rates result in a great deal of plastic waste and accumulation of plastic litter in the environment. In urban and suburban landscapes, this plastic litter accumulates in streams, where it can be transported to coastal and marine ecosystems as well as affect the ecology of these streams themselves. With the goal of decreasing plastic pollution, several municipal governments in southeast Pennsylvania have enacted bans on the distribution of single-use plastics, such as shopping bags and drinking straws. However, the impact of such legislation on the abundance and types of plastic litter in streams has not been widely documented. We are using a replicated before-after-control-impact study to ask how municipal-scale plastic bans affect the abundance and types of anthropogenic litter in streams. We are collecting and categorizing litter monthly (from September 2023 through December 2024) from nine urban headwater streams, each with homogeneous policy regarding single-use plastics within their watersheds: three streams without plastic bans, three streams that have had plastic bans for at least one year, and three streams in which plastic bans were enacted beginning in January 2024. Here, we will share preliminary results of this in-progress work based on the first seven months of data collection, which spans before and after enactment of single-use plastic bans.

Lauren Kuehne (Primary Presenter/Author), Omfishient Consulting, LLC , lauren.kuehne@gmail.com;

Victoria Moreira (Co-Presenter/Co-Author), West Chester University , vm1020492@wcupa.edu;

Adeline Brown (Co-Presenter/Co-Author), West Chester University , ab951319@wcupa.edu;

Amanda Cohan (Co-Presenter/Co-Author), West Chester University , ac995014@wcupa.edu;

Mara Jansons (Co-Presenter/Co-Author), West Chester University , mj982909@wcupa.edu;

Gianna Parrish (Co-Presenter/Co-Author), West Chester University , gp1008437@wcupa.edu;

Brianna White (Co-Presenter/Co-Author), West Chester University , bw956444@wcupa.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Efficiency of Low Impact Development on Urban Stormwater in Phnom Penh Capital of Cambodia Cambodia is at an early stage of development, with 21% of people presently living in cities. Phnom Penh, the capital and largest city of Cambodia, is under urbanization pressure with a population of 2.1 million and the annual growth rate of 3.2% in 2019. In this regard, aging infrastructure needs an upgrade or replacement with a new design considering a percentage, as high as possible, of permeable surfaces in urban areas. Low Impact Development (LID), including green infrastructure, should be taken into account in planning and design approaches to mitigate land development impacts on the environment. This study aims to evaluate the efficiency of LID scenarios on surface runoff reduction, peak flow reduction, and pollutant removal under rainfall patterns using PCSWMM model in Boeng Trabek sewerage system, Phnom Penh. Flow monitoring and water quality sampling during three rainfall events were conducted in a main conduit for testing model performance. Six types of LIDs (Infiltration trenches, bioretention, porous pavements, rain garden, green roof, and rain barrels) were implemented in an applicable proportion of existing sub-catchments. For every selected rainfall event, LIDs could reduce in average 48% of surface runoff, 35% of peak flow and increase infiltration rate to 90%. For water quality (COD, NO3, PO4, and TSS), the average sub-catchment’s washoff removal and outlet’s total pollutant removal is 55%. In summary, the implementation of LIDs has significant impact on runoff reduction, peak flow reduction, and pollutant removal. The results provide concrete evidence for stakeholders to consider LIDs technique for sustainable development.

MENG HOUR HOUT (Primary Presenter/Author), Institute of Technology of Cambodia , houtmenghour78@gmail.com;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

CATCHMENT FOREST RESTORATION EFFECT ON INSTREAM ORGANIC MATTER DECOMPOSITION AND BENTHIC INVERTEBRATE COMMUNITIES The Atlantic Forest, a Brazilian hotspot of biodiversity, has been deforested in the last centuries. Land-use changes threaten water quality, biodiversity and functioning of riverine ecosystems. To counteract these effects, restoration of the natural vegetation at the landscape level is needed. Brazil aims to restore 12 million hectares of native forest in the next 16 years, however, there is an urgent need to assess the effect of forest restoration on stream structure and processes. This study aims to assess the effects of forest restoration on organic matter decomposition and on the associated invertebrates. We studied 30 headwater streams, located in Paraíba do Sul river basin. Different stages of restoration were considered ranging from natural forest, old and young forest restoration and pasture. We assessed the microbial decomposition potential of cellulose (using cotton strips) and leaf litter decomposition of Guazuma ulmifolia in coarse (where both invertebrates and microbes can enter) and fine (from where invertebrates are mostly excluded) mesh bags. Invertebrates colonizing leaf litter in coarse mesh bags were also assessed. Results show that leaf litter decomposition rates in coarse mesh bags were highest in natural forest and old restoration streams, aligning with the abundance and biomass of invertebrates from the Ephemeroptera, Plecoptera, and Trichoptera orders. Pasture streams showed the highest decomposition rates of cellulose and litter in fine mesh bags. Forested streams showed the highest coarse/fine mesh decomposition rates. In conclusion, long-term restoration is essential to achieve stream functioning and diversity comparable to that of natural forests.

Vitor Gomes dos Santos (Primary Presenter/Author), University of São Paulo, USP/ESALQ, Dept of Forest Sciences, Brazil , vitor.gomes020@usp.br;

Paula Caroline dos Reis Oliveira (Co-Presenter/Co-Author), University of São Paulo, USP/ESALQ, Dept of Forest Sciences, Brazil , reolivpaula@gmail.com;

Verónica Ferreira (Co-Presenter/Co-Author), MARE - Marine and Environmental Sciences Centre, ARNET - Aquatic Research Network, University of Coimbra , veronica@ci.uc.pt;

Silvio Frosini de Barros Ferraz (Co-Presenter/Co-Author), University of São Paulo, USP/ESALQ, Dept of Forest Sciences, Brazil , silvio.ferraz@usp.br;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

The Influence of Bedrock Composition on Surface Water Chemistry in the Delaware River Basin The Delaware River Basin (DRB) spans across several states in the Northeast and provides drinking water to major metropolitan regions, including Philadelphia. In natural waterways, the weathering of bedrock and other geochemical processes impact the chemical composition of surface waters. Magnesium (Mg2+) and calcium (Ca2+) ions, the main constituents of total hardness (TH), are found in carbonate (CaCO3)-bearing bedrock and may enter a waterway through erosion and weathering processes. Here, we present a study aimed towards developing a comprehensive understanding of how local geology interacts with water chemistry parameters, specifically TH, among 30 different rivers and streams in the DRB. Geochemical data from the years 2013 through 2021 suggests that Ca2+ and Mg2+ are found in higher concentrations in stream water in basins formed from both crystalline and sedimentary bedrock, in comparison to those formed from crystalline bedrock only. Interestingly, surface water chemistry from the Philadelphia sites shows results that are not reflective of the non-carbonate pelitic schist and gneiss bedrock of the Wissahickon Formation. In contrast, ion and hardness concentrations are comparable to other sites with carbonate-bearing bedrock. This may be due to a number of reasons, including land usage and industrial activity in an urban area. This study serves as a basis to create a deeper understanding of the interactions between bedrock and surface water chemistry in the DRB and the results may be used in future reports and research by the Delaware River Watershed Initiative to provide a more comprehensive model of water chemistry in the Basin.

Kayla Aughenbaugh (Primary Presenter/Author,Co-Presenter/Co-Author), Western Washington University , aughenk@wwu.edu;

Michelle Gannon (Co-Presenter/Co-Author), Academy of Natural Sciences of Drexel University , meg355@drexel.edu;

David Velinsky (Co-Presenter/Co-Author), Drexel University Biodiversity, Earth, and Environmental Science Department , djv23@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Biogeochemical recovery of relict hydric soils on a restored floodplain after three years In the Mid-Atlantic region of the US, historic and contemporary land use practices have resulted in large deposits of legacy sediment filling valley bottoms. Buried beneath these legacy sediment deposits are organic-rich (C and N) soils from pre-colonial surficial marshes, bogs, or wetlands. Current stream and floodplain restoration practices aim to remove overlying legacy sediments and enhance the hydrologic connection and nutrient exchange between the stream and floodplain. The buried organic horizon is not typically considered in these restorations and is removed and discarded during this process. These relic organic layers could be leveraged to improve nitrogen removal through denitrification by the “daylighting” of these soil horizons on floodplains and their hydrologic reconnection to the stream. Relict soils could also help activate historic soil microbiomes and enhance and “rewild” the restored floodplains. This study compared changes in soil and pore water nitrogen (N) concentrations and process rates for relict, hydric soils against contemporary wetland and restored floodplain soils over a three-year period. Following exposure to the floodplains surface, an initial high release of nitrogen and organic carbon was seen in the first year of the study across all soil types. Relict hydric soil N process rates remained low compared to contemporary wetland soil rates at the conclusion of the study and higher than restored floodplain soil rates. These results may be an indication that the biogeochemical recovery of relict soils may be slow and require more than three years exposure on the floodplain to match contemporary soil rates.

Alexis Yaculak (Primary Presenter/Author), University of Delaware , yaculak@udel.edu;

Shreeram Inamdar (Co-Presenter/Co-Author), University of Delaware , inamdar@udel.edu;

Jinjun Kan (Co-Presenter/Co-Author), Stroud Water Research Center , jkan@stroudcenter.org;

Marc Peipoch (Co-Presenter/Co-Author), Stroud Water Research Center , mpeipoch@stroudcenter.org;

Joseph Galella (Co-Presenter/Co-Author), University of Delaware , jgalella@udel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Fingerprinting the Delaware River Watershed using Piper Diagrams Since 2013, surface water samples have been collected seasonally from 35 streams in the Delaware River Watershed (DRW) through the Delaware River Watershed Initiative. This region spans many distinct lithologies and land uses. Numerous analytes were measured in each sample including Alkalinity, Chloride, Sulfate, Calcium, Magnesium, and Sodium. To classify the hydrochemical characteristics of surface water of subwatersheds within the DRW, Piper diagrams were created using the smwrGraphs package for R and the piperPlot function. Piper diagrams are a useful tool when analyzing large datasets and help identify the fingerprint of the hydrofacies with which the water is interacting. Here, we present a seasonal and temporal comparison of each location. Additionally, subwatersheds are analyzed to determine small scale discrepancies within the subwatershed. Finally, we compare each subwatershed to determine if ionic shifts occurred spatially. Preliminary results suggest there were temporal shifts in the cationic and anionic hydrochemistry. Additionally, there are discrepancies between subwatersheds which may be due to a shift in land use, chemical pollution, removal of the sources of chemical pollution, or novel hydrochemical interactions with ambient rocks.

Leslie Wong (Primary Presenter/Author), Drexel University , lmw357@drexel.edu;

Timothy Maguire (Co-Presenter/Co-Author), The Academy of Natural Sciences of Drexel University , tjm438@drexel.edu;

Michelle Gannon (Co-Presenter/Co-Author), Academy of Natural Sciences of Drexel University , meg355@drexel.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Transfer of microplastics from one trophic level vs two in a freshwater food web Microplastics are emerging pollutants that may harm aquatic organisms. Microplastics can adsorb onto gill surfaces, interfere with feeding structures, or be mistakenly ingested and bioaccumulate in living organisms. There are reports of ingested microplastics causing intestinal blockage, reduced foraging, and decreased energy reserves. These harmful effects depend on various factors such as size, shape, gut morphology, species, and abiotic factors. Trophic transfer of microplastics in food webs can occur directly (from water and sediments) and indirectly from contaminated prey and might have adverse impacts on wildlife and humans. We investigated differences in microplastic uptake from different food items of variable nutritional quality in freshwater midge larvae (Chironomus riparius) and crayfish. Crayfish were fed contaminated prey (midge larvae) versus artificial diets of differing nutritional quality (acting like sediments and carriers of microplastics). For indirect exposure, C. riparius larvae were fed spherical blue microplastics (polyethylene microspheres, size:53-63 µm) for 48 hours, then fed to crayfish. Microplastics were extracted from midge carcasses, crayfish gut, and gills using 10 % potassium hydroxide digestion and filtration. More microplastics were found in the guts of crayfish fed an artificial diet compared to midge larvae. Very few microplastic particles were found to adsorb onto gill tissue, supporting our hypothesis that the gut is the critical retention site for microplastics in crayfish. Additional experiments are underway to determine the importance of food quality on ingestion and gut retention rates.

Mohsin Khan (Primary Presenter/Author), Ohio University Athens Ohio United States , mk228822@ohio.edu;

Kelly Johnson (Co-Presenter/Co-Author), Ohio University , johnsok3@ohio.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Insights into Microplastics Accumulation and Distribution in Freshwater Environments Plastics have become an essential part of our daily lives. However, little attention is paid to the detrimental effects of massive plastic use, which generates small pieces known as microplastics that persist in the environment. Although regulations to control and remediate microplastics in the environment have not been published, many studies have reported adverse impacts of microplastics on living organisms. To support the establishment of regulations and the mitigation of this pollutant, we aimed to study how microplastic transports and persists in freshwater environments, connecting crucial media to food chains and human exposure. Our study collected sediment cores in different watersheds and land covers. We measured the chronology of the sediment cores, sedimentation rate, organic matter content, population density, land cover types, and microplastic concentration in these samples. Microplastics were counted under a stereomicroscope and identified morphology, size, and color. We classified morphology as fiber, fragment, film, and pellet. Contrary to expectations, our results found that urban area and population density were not correlated with microplastic concentrations in these sediment cores. Interestingly, microplastic concentrations were observed to have negative correlations with sedimentation rate and organic matter content, but positive correlation with open-water area. In freshwater sedimentary settings, human activities with greater plastic use are not the only parameters controlling microplastic pollution. Instead, external factors such as land type, sedimentation rate, and organic matter content should not be overlooked in understanding the distribution of microplastics in freshwater sedimentary environments.

Jutamas Bussarakum (Primary Presenter/Author), Pennsylvania State University , jkb6426@psu.edu;

Samuel Cohen (Co-Presenter/Co-Author), Pennsylvania State University , sxc5884@psu.edu;

Kimberly Van Meter (Co-Presenter/Co-Author), Pennsylvania State University , vanmeterkvm@psu.edu;

Lisa Emili (Co-Presenter/Co-Author), Pennsylvania State University , lae18@psu.edu;

Nathaniel Warner (Co-Presenter/Co-Author), Pennsylvania State University , nrw6@psu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

Evaluating the Digestive System Microplastic Content of Central Appalachian Stream Fishes Within the past two decades investigation of microplastic pollution has increased in response to accumulation in global water systems and the possibility for human and animal ingestion. It is estimated that humans ingest/inhale tens to hundreds of thousands of microplastic particles annually. Despite a growing awareness of the issue, there is not yet a standard procedure for the extraction and measurement of microplastic particles from organisms or bodies of water. Methodologies vary from visual inspection to chemical analyses but findings are often largely underestimated due to procedural complexities. The purpose of this study is to determine the extent of microplastic pollution in the digestive tracts of small freshwater fishes representing different functional feeding groups and from relatively pristine and heavily impacted streams within north central West Virginia. To extract microplastic particles, the digestive tract of individual fish was removed and digested in a 10% KOH/volume solution. Samples were then filtered through 500, 300, 212, 106 and 20?m sieves, allowed to dry, and visually inspected for microplastic content. All samples had an accompanying air control and strict contamination protocol was followed to lessen confounding microplastic interference. Preliminary results indicated a variety of primarily microplastic fibers in trial samples including the species northern hog sucker, Hypentelium nigricans (benthic invertivore) and central stoneroller, Campostoma anomalum (herbivore/detritivore), among others. In this initial study, we will present the extent and variation of microplastic contamination within the digestive tracts of common stream fishes across several feeding styles and a range of watershed conditions.

Isabella Tuzzio (Primary Presenter/Author), West Virginia University , imt00004@mix.wvu.edu;

Brent Murry (Co-Presenter/Co-Author), West Virginia University , brent.murry@mail.wvu.edu;

Caroline Arantes (Co-Presenter/Co-Author), West Virginia University , caroline.arantes@mail.wvu.edu;

6/3/2024  |   15:00 - 17:00   |   Liberty Ballroom D

EVAULATING THE SPATIAL AND TEMPORAL VARIABILITY OF MICROPLASTICS IN MACROINVERTEBRATES WITHIN THE SPRUCE CREEK WATERSHED, CENTRAL PENNSYLVANIA Microplastics are a rising concern globally and are increasingly being reported to occur in freshwater environments. Despite this recognition of their prevalence, there is still limited understanding of the potential impacts of microplastics on aquatic life. Macroinvertebrates are critical components of freshwater streams, occupying an intermediate position in the trophic web, and are key organisms used in freshwater biomonitoring. Recent studies have found that microplastics can accumulate in macroinvertebrate tissues, however there is some evidence that there is variability in how taxa accumulate microplastics. In addition, the abundance of microplastics and the macroinvertebrate community assemblage vary seasonally, so the impacts of microplastics and their potential to transfer through the trophic web may vary. To evaluate the spatial and temporal variability of microplastics in macroinvertebrates, we will examine archived invertebrate samples collected at multiple periods in 2021 and 2022 across a gradient of land use in the Spruce Creek Watershed, Pennsylvania. The presence of microplastics in macroinvertebrate tissue from different functional feeding groups will be assessed and evaluated across sampling periods. This research will increase our knowledge on the fate, occurrence, and potential for biomagnification of microplastics in freshwater ecosystems.

Emily Roush (Primary Presenter/Author), The Pennsylvania State University , edr5207@psu.edu;

Morgan Watkins (Co-Presenter/Co-Author), The Pennsylvania State University , mlw6200@psu.edu;

Mason Ward (Co-Presenter/Co-Author), The Pennsylvania State University , msw5688@psu.edu;

Francesca Ferguson (Co-Presenter/Co-Author), The Pennsylvania State University , fmf5061@psu.edu;

Lisa Emili (Co-Presenter/Co-Author), Pennsylvania State University , lae18@psu.edu;

Nathaniel Warner (Co-Presenter/Co-Author), Pennsylvania State University , nrw6@psu.edu;

Heather Gall (Preisendanz) (Co-Presenter/Co-Author), Pennsylvania State University , heg12@psu.edu;

Jon Sweetman (Co-Presenter/Co-Author), The Pennsylvania State University , jfs6745@psu.edu;