SFS Annual Meeting

6/06/2024  |   10:30 - 10:45   |  Philadelphia Ballroom

PLASTICS BY PROXY? INCORPORATING MICROPLASTICS INTO LONG TERM WATER QUALITY MONITORING Microplastics, or plastic particles between 0.1 um and 10 mm in size, are an emergent contaminant in aquatic ecosystems. Due to widespread use of plastics in modern society, and the fact that plastics will fragment into smaller and smaller pieces rather than break down fully, Microplastics are ubiquitous in ecosystems and organisms, although the scope and impacts of this are still uncertain. In the suburban Lamprey River watershed, monthly water quality samples have been taken for over 20 years at 19 different sites. The goal of the sampling is to understand drivers of spatial and temporal variability in water quality, with sites spanning a range of stream order, watershed area, and land uses including discharge of treated sewage effluent. Here, we outline an approach to incorporate a low-cost method to quantify microplastics to explore the relationships between microplastic abundance and the land use and water quality metrics which are more commonly measured. Water quality measurements include major cations and anions, dissolved organic matter, and inorganic nutrients. Since September 2023 we have analyzed whole water samples for microplastics using a Nightsea stereomicroscope fluorescence adapter, a relatively low-cost method to quantify the amount, type, and size of microplastics in the water samples. By incorporating these methods, we are exploring the relationship between microplastic abundance and both water quality metrics and land use within the watersheds. Analysis of samples is still ongoing, although preliminary results have found more than 30,000 particles per liter in some samples.

William G. McDowell (Primary Presenter/Author), Merrimack College, wgmcdowell@gmail.com;

Alyssa Cugno (Co-Presenter/Co-Author), Merrimack College, cugnoa@merrimack.edu;

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

William McDowell (Co-Presenter/Co-Author), Department of Natural Resources and the Environment, University of New Hampshire, 03824, Durham, New Hampshire, bill.mcdowell@unh.edu;

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6/06/2024  |   10:45 - 11:00   |  Philadelphia Ballroom

MERCURY CYCLING DURING ACID RAIN RECOVERY AND CLIMATE CHANGE AT THE 14 FORESTED CATCHMENTS OF THE GEOMON MONITORING NETWORK, CZECH REPUBLIC Central Europe has received high emissions of sulfur (S) and associated mercury (Hg) from coal-fired power plants. Emissions peaked in the 1980s and 1990s and have since been sharply reduced. To evaluate current conditions and the effects of legacy Hg deposition, we investigated Hg cycling at the 14 forested GEOMON catchments managed by the Czech Geological Survey. The temperate forest catchments had variable exposure to Hg emissions, and have variable size, elevation, and bedrock type. The catchments were monitored monthly for Hg inputs (bulk precipitation, throughfall, litterfall) and outputs (stream runoff) for two full years in 2021-2022. Air Hg concentrations at all sites were assessed using passive samplers, and soil Hg pools were assessed through random sampling. Hg sources and sinks were assessed using a catchment mass balance approach. Gaseous elemental mercury (GEM) concentration was low and fairly stable (1.25 to 1.66 ng m-3) at the 14 catchments. The main pathway of Hg input was litterfall. Across the 14 GEOMON catchments, spruce litterfall Hg deposition averaged 44.5±15.7 µg m-2 yr-1. Hg deposition via throughfall was three-fold higher than in bulk deposition, but was an order of magnitude lower than litterfall Hg deposition, averaging 4.5±1.5 µg m-2 yr-1. Stream Hg output varied greatly across catchments and averaged 1.5±1.7 µg m-2 yr-1. Thus the average retention rate, calculated as a ratio of average Hg inputs (throughfall + litterfall) to average Hg outputs in stream runoff of these 14 catchments, representing the central European forest ecosystems, was 97%.

Tomas Navratil (Co-Presenter/Co-Author), Czech Academy of Sciences, NavratilT@gli.cas.cz;

Jamie Shanley (Primary Presenter/Author), U.S. Geological Survey, jshanley@usgs.gov;

Filip Oulehle (Co-Presenter/Co-Author), Czech Geological Survey, filip.oulehle@geology.cz;

Jan Rohovec (Co-Presenter/Co-Author), Czech Academy of Sciences, rohovec@gli.cas.cz;

Tereza Novakova (Co-Presenter/Co-Author), Czech Academy of Sciences, novakova@gli.cas.cz;

Michal Roll (Co-Presenter/Co-Author), Czech Academy of Sciences, roll@gli.cas.cz;

Miroslav Tesa? (Co-Presenter/Co-Author), Czech Academy of Sciences, miroslav.tesar@iol.cz;

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6/06/2024  |   11:00 - 11:15   |  Philadelphia Ballroom

Temperature interacts with nutrient availability to alter nitrogen dynamics in stream ecosystems Climate warming and eutrophication are important drivers of global environmental change, and both influence nitrogen (N) cycling in freshwater ecosystems. Yet, little is known about how the effects of warming on N storage and fluxes are mediated by the identities or availability of limiting nutrients. Over three summers, we conducted whole-stream enrichments of N and phosphorus (P) in four Icelandic streams along a natural 5°C gradient of ambient temperature (year 1: ambient concentrations, year 2: +200 µg P/L, year 3: +200 µg N/L). Each summer, we conducted simultaneous 5-d pulse-releases of 15N (labelled ammonium and nitrate added together, both enriched to ~15,000 per mil), followed by ~48 d of post-release sampling. All major food-web compartments were quantitatively sampled on each of 7 dates (one pre-15N addition, six post) at 6 transects in each stream in each year, generating >8000 isotope values. We are analyzing this large data set using isotracer, an R package that implements a Bayesian approach based on Hidden Markov Models to estimate nutrient-flow parameters simultaneously across all 12 food-web networks (three years x four streams). Here, we present preliminary results, highlighting the interacting effects of temperature and nutrient enrichment on N uptake rates, N turnover rates, and total N fluxes, as well as their uncertainty. We will also assess the ability of isotracer to compare alternative hypotheses of food-web structure based on model selection.

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

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

Wyatt Cross (Co-Presenter/Co-Author), Montana State University, wyatt.cross@montana.edu ;

James Hood (Co-Presenter/Co-Author), The Ohio State University, hood.211@osu.edu;

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

Jill Welter (Co-Presenter/Co-Author), St. Catherine University, jill.welter@gmail.com;

Jon Olafsson (Co-Presenter/Co-Author), Iceland Marine and Freshwater Research Institute, jon.s.olafsson@hafogvatn.is;

Gisli Gislason (Co-Presenter/Co-Author), University of Iceland, gisli@ui.is;

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6/06/2024  |   11:15 - 11:30   |  Philadelphia Ballroom

INCREASE IN LABILE CARBON AVAILABILITY CAUSES SPATIAL AND TEMPORAL CHANGES IN IN-STREAM NUTRIENT UPTAKE IN AN URBAN MEDITERRANEAN STREAM Wastewater treatment plant (WWTP) effluents can influence sub-daily patterns of nutrient load in receiving streams. This is especially noticeable in Mediterranean regions, where receiving streams have a limited capacity to dilute nutrient excesses. We hypothesized that a low availability of labile carbon (C) limits the heterotrophic activity of urban streams, and thus, we expected that an increase in labile C would increase in-stream nutrient uptake rates (U). To test this idea, we added a C-labile-enriched brewery by-product for 4 days to a forested headwater Mediterranean stream receiving a WWTP effluent input. The addition was done in summer, when the WWTP effluent accounted for 100% of stream flow. We collected hourly water samples upstream and 20 and 175 m downstream of the C addition point before and during the C addition to examine the persistence of sub-daily changes in U in the downstream direction of soluble reactive phosphorus (SRP), ammonium (NH4), and nitrate (NO3). For the three nutrients, the effect of C addition in hourly U was only significant 20 m downstream of the addition point during some hours of the day: U increased during daytime for SRP and NO3, and for NH4 during nighttime. Sub-daily changes in UNH4 and UNO3 showed a positive relationship with concentrations of NH4 and NO3, respectively, being these relationships stronger during the C addition. Our results pointed out that alleviation of labile C limitation in urban streams can increase nutrient retention at sub-daily time scales, but this effect does not persist along the stream.

David Pineda-Morante (Primary Presenter/Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, dpineda@ceab.csic.es;

Miquel Ribot (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, mribot@ceab.csic.es;

Susana Bernal (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, sbernal@ceab.csic.es;

Sara Castelar (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, saracastelar@ceab.csic.es;

Esperança Gacia (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, gacia@ceab.csic.es;

Anna Lupon (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, alupon@ceab.csic.es;

Stephanie N. Merbt (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, stephanie.merbt@ceab.csic.es;

Francesc Sabater (Co-Presenter/Co-Author), Universitat de Barcelona, fsabater@ub.edu;

Helena Guasch (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, helena.guasch@ceab.csic.es;

Eugènia Martí (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), eugenia@ceab.csic.es;

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6/06/2024  |   11:30 - 11:45   |  Philadelphia Ballroom

Balancing spatial and temporal resolution for optimal water quality monitoring Water quality monitoring for the purposes of both water resource management and interpretation of biogeochemical function has historically relied on costly, time- and labor-intensive grab samples from aquatic ecosystems at weekly or monthly time scales. Although still valuable, these efforts are limited in both temporal and spatial scope, potentially limiting our understanding of freshwater ecosystem function. Recent methodological advancements, such as improved sensor technology and the development of platforms for collecting water quality data with high spatial resolution, have mobilized progress in remote monitoring of water quality and have resulted in more spatially and temporally rich datasets. These datasets have the potential to revolutionize the insights we can gain about stream ecosystem function and allow for more rapid detection of events concerning resource managers, such as the presence of harmful algal blooms. In this study, we leverage a dataset that includes water quality data collected with both high spatial and temporal resolution using in situ high-frequency sensors and spatially-resolved data collected from a novel, ultralight sampling platform to consider tradeoffs between sampling efforts that prioritize capturing spatial or temporal variability. Considering constraints such as limited time, resources, alongside the imperative to minimize the environmental impact of research, we use these data from an agricultural watershed in Minnesota, USA to explore optimal monitoring strategies combining spatial and temporal efforts for effective water quality management and deeper insights into biogeochemical function.

Allison Herreid (Primary Presenter/Author), USDA-ARS, allison.herreid@usda.gov;

Brent Dalzell (Co-Presenter/Co-Author), USDA-ARS, bdalzell@umn.edu;

Kade Flynn (Co-Presenter/Co-Author), University of Minnesota, flynn574@umn.edu;

John Baker (Co-Presenter/Co-Author), USDA-ARS, john.baker@usda.gov;

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6/06/2024  |   11:45 - 12:00   |  Philadelphia Ballroom

USING MULTI-SOLUTE CONCENTRATION-DISCHARGE (CQ) RESPONSES TO DOCUMENT INTERACTING DRIVERS OF CHANGE Despite being a water-rich region, the Southeastern United States is experiencing intensified droughts as a result of climate change. In addition, this region is vulnerable to increasing water use via anthropogenic water demands. Our goal was to explore how the interaction between intensified wet-dry cycles and human water use emerge as changing surface water quality, as expressed by concentration-discharge (CQ) relationships. We leveraged a long-term (21-29 years) record of paired water chemistry and continuous stream discharge data that span the lowest and highest recorded flows on record from six sites distributed within the Ichawaynochaway Creek Basin in Southwestern Georgia. The water chemistry data include total suspended solids (TSS), dissolved inorganic and total organic carbon (DIC, DOC), nitrogen species (nitrate, NO3--N ammonium, NH4+-N), soluble reactive phosphorus (SRP), and other physicochemical data (pH, alkalinity). For each site and solute, we characterized seasonal and annual export patterns using the C-Q slopes. To further explore trends in CQ responses, we conducted a trajectory analysis, a method used in community ecology, to capture seasonal and annual shifts in CQ behaviors from a multi-solute perspective. Using the trajectory analysis, we found climate-driven differences in CQ trajectories, where the largest divergence in the CQ responses occurred during years of extreme drought. These emergent patterns suggest that there may be long-term changes to ecosystem function as water availability is changed by human influences and extreme drought.

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

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

Nicholas Marzolf (Co-Presenter/Co-Author), J.W. Jones Ecological Research Center, nmarzolf@jonesctr.org;

Stephen Plont (Co-Presenter/Co-Author), The University of Alabama, plontste@gmail.com;

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

Stephen W. Golladay (Co-Presenter/Co-Author), J.W.Jones Research Center, steve.golladay@jonesctr.org;

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