Back to top

SFS Annual Meeting

2021 Detailed Schedule

Click titles to view presentation information.

A research directive for positive biotic interactions in freshwaters [Oral Presentation]

Brandon K. Peoples (Primary Presenter/Author)
Clemson University, peoples@clemson.edu;

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

Bryan Brown (Co-Presenter/Co-Author)
Virginia Tech, stonefly@vt.edu;

Robert Creed (Co-Presenter/Co-Author)
Appalachian State Universtiy, creedrp@appstate.edu;

Emmanuel Frimpong (Co-Presenter/Co-Author)
Virginia Tech, frimp@vt.edu;

James Skelton (Co-Presenter/Co-Author)
University of Florida, skelto3@gmail.com;

Abstract: Positive interspecific interactions such as mutualism, commensalism, and facilitation are globally ubiquitous. Recent advances have brought the study of positive interactions in freshwater systems to a point where synthesis is warranted. It is well known that interaction outcomes vary with abiotic and biotic context. However, only a few of studies have examined context dependency in positive interactions in freshwater systems. Likewise, positive interactions incur costs as well as benefits; conceptualising interactions in terms of net cost/benefit to participants will help to clarify complex interactions. It is likely that there are many positive interactions that have yet to be discovered in freshwater systems. To identify these interactions, we encourage inductive natural history studies combined with hypotheses deduced from general ecological models. Research on positive interactions must move beyond small?scale experiments and observational studies and adopt a cross?scale approach. Likewise, we must progress from reducing systems to oversimplified pairwise interactions, toward studying positive interactions in broader community contexts. Positive interactions have been greatly overlooked in applied freshwater ecology, but have great potential for conservation, restoration, and aquaculture.

BETA DIVERSITY PATTERNS AND DRIVERS ACROSS CONTRASTING COASTAL PLAIN WETLANDSCAPES [Oral Presentation]

Joshua Epstein (Primary Presenter/Author)
University of Florida, jmepstein12@ufl.edu;

Olivia Cacciatore (Co-Presenter/Co-Author)
University of Florida, o.cacciatore@ufl.edu;

Matthew Cohen (Co-Presenter/Co-Author)
University of Florida, mjc@ufl.edu;

Abstract: Geographically isolated wetlands (GIWs) are wetlands surrounded by uplands that lack persistent surface water inlets or outlets. Despite their infrequent surface water exchanges, GIWs exhibit various modes and frequencies of surface and subsurface flows over space and time. Differences in GIW connectivity and inundation patterns within wetlandscapes (i.e., wetland-rich landscapes) provide insight on the diversity of supported wetland functions. The provision of habitat for wetland flora and fauna is one such function, with wetlandscapes providing increased habitat heterogeneity and beta diversity (i.e., taxonomic dissimilarity) when their GIWs differ in hydrologic and geographic properties. To better understand differences in wetlandscape beta diversity, we selected 16 GIWs from across three Florida Coastal Plain wetlandscapes, surveyed vegetation and fishes twice annually between summer 2018 and spring 2020, and measured beta diversity for each taxonomic group. We also recorded wetland stage and collected biogeochemical measurements to assess the physical and chemical hydrologic influences on taxonomic dissimilarity using constrained ordination. Our results suggest informative differences in beta diversity patterns and drivers across taxonomic groups and wetlandscapes that shed light on dominant metacommunity processes and have implications for the conservation of GIW biota.

CHARACTERIZNG COMMUNITY-LEVEL SIZE SPECTRA IN MID-ATLANTIC, PIEDMONT SREAMS OF VIRGINIA (USA) [Oral Presentation]

Daniel McGarvey (Co-Presenter/Co-Author)
Center for Environmental Studies, Virginia Commonwealth University, djmcgarvey@vcu.edu;

Giancarlo Racanelli (Primary Presenter/Author)
Virginia Commonwealth University, racanellig@mymail.vcu.edu;

Abstract: Many aquatic communities demonstrate an inverse scaling relationship between average body mass and density. Using quantitative samples of benthic macroinvertebrates and fishes, we modeled this relationship in three Mid-Atlantic, Piedmont streams where little empirical research has been conducted. The size-spectra method, in which individuals are identified by size, not taxonomy, and are aggregated within log2 dry mass bins was used to model density as a power-law function of individual mass. Our size-spectra models provide new insight to aquatic community structure in the study region and are particularly notable because they combine macroinvertebrate and fish data in community-level models. Time-staggered samples were also used to test the hypothesis that size-specific fish density is an instantaneous function of invertebrate density. Fish data were collected in September, but macroinvertebrates were collected in July, August, and September. By comparing macroinvertebrate samples from different months with the September fish data, we assess whether fish density is more closely associated with contemporaneous or prior invertebrate density.

CLIMATE-DRIVEN VARIATION IN A SOUTHERN APPALACHIAN STREAM INVERTEBRATE COMMUNITY DIFFERS BY HABITAT TYPE [Oral Presentation]

Phillip Bumpers (Primary Presenter/Author)
Odum School of Ecology, University of Georgia, bumpersp@gmail.com;

Seth Wenger (Co-Presenter/Co-Author)
Odum School of Ecology, University of Georgia, swenger@uga.edu;

Amy Rosemond (Co-Presenter/Co-Author)
University of Georgia, rosemond@uga.edu;

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

Mary Freeman (Co-Presenter/Co-Author)
US Geological Survey, mcfreeman@usgs.gov;

Sue Eggert (Co-Presenter/Co-Author)
USDA Forest Service, Northern Research Station, seggert@fs.fed.us;

J. Bruce Wallace (Co-Presenter/Co-Author)
Dept. Entomology and Odum School of Ecology, University of Georgia, bwallace@uga.edu;

Abstract: Long-term data can provide insights into how stream populations and communities respond to climate change, driven by both gradual changes and extreme events in hydrologic and thermal regimes. These master variables define the physical environment and control biological activity in streams. Thus, responses of communities to such variables can help inform conservation and management. Using a long-term (13-yr) data set of monthly invertebrate abundance and biomass in a southern Appalachian stream, we quantified changes in community structure and explored whether observed differences were associated with variation in discharge and temperature. Further, we assessed whether habitat type (rock-face vs. cobble) mediates response to climate variables. Initial analyses suggest that changes in cobble community structure were not related to any climate variables that we tested, despite periods of historically intense drought and rainfall during the study. Changes in rock-face community structure were correlated with total annual precipitation and the mean annual minimum discharge. Our results suggest that habitat type mediates responses to climate variation and that invertebrate communities in the dominant cobble habitat of small forest streams are relatively robust to historical variation in discharge and temperature over the 13-yr period.

Community stability in stream networks: Experimentally disentangling the roles of dispersal mode and network position [Oral Presentation]

Sara Cathey (Primary Presenter/Author)
Virginia Tech, catheyse@vt.edu;

Christopher Swan (Co-Presenter/Co-Author)
University of Maryland Baltimore County, cmswan@umbc.edu;

Eric Sokol (Co-Presenter/Co-Author)
Battelle, National Ecological Observatory Network (NEON), sokole@gmail.com;

Kurt Anderson (Co-Presenter/Co-Author)
University of California, Riverside, kurt.anderson@ucr.edu;

Bryan Brown (Co-Presenter/Co-Author)
Virginia Tech, stonefly@vt.edu;

Abstract: Community assembly may vary across stream networks due to differences in environmental filtering and regional processes, such as dispersal. Stream insect dispersal varies by mode, and this variability may affect the recovery of streams at the local and network scale. To examine the effect of different dispersal modes on community assembly and stability, we conducted a field experiment using streamside flumes at Coweeta Hydrologic Lab. We built 18 flumes and divided them into four channels. Each channel received one dispersal treatment: aquatic drift only, aerial flight only, open to drift and aerial dispersal, and no drift and aerial dispersal. We completed the flumes in March 2019 and began sampling the channels in May. Following two initial sampling events, we applied a disturbance treatment across all of the flumes by raking the stream sediments and then continued to sample monthly. Preliminary data support two of our predictions: communities more central in the network are more stable than headwaters; and channels that received drift dispersal recover faster. These findings confirm community assembly and stability varies with dispersal mode and network location, which could improve restoration and management strategies in river networks.

COMPARING COMMUNITY REESTABLISHMENT IN INTERMITTENT ECOSYSTEMS: SIMILARITIES BETWEEN STREAMS AND WETLANDS IN INITIAL DEVELOPMENT [Oral Presentation]

Chelsea Smith (Primary Presenter/Author)
The Jones Center at Ichauway, chelsea.smith@jonesctr.org;

Stephen Golladay (Co-Presenter/Co-Author)
The Jones Center at Ichauway, steve.golladay@jonesctr.org;

Abstract: The study of intermittent streams and wetlands role within landscape has increased as their protection has diminished. Macroinvertebrates that exist within these habitats must be able to survive desiccation or recolonize when rewetting occurs. Comparing the communities following rewetting between these two intermittent ecosystems could provide insight into what factors control their restructuring. We examined macroinvertebrate reestablishment in an intermittent stream and a geographically isolated wetland in southwest Georgia with. In 2015 samples at three sites within the intermittent stream were taken monthly from dominant habitat types as well as drift samples to examine colonization sources following rewetting. In 2018, we examined macroinvertebrates within a cypress swamp using litter bags following inundation. Similarities between these two ecosystems were seen with early colonizers consisting of crustacean taxa as well as Chironomidae. Within two months, differences could be seen as more rheophilic taxa began to colonize the intermittent stream while wetland samples continued to be dominated by crustaceans and Chironomidae taxa as well as some predators. Similarities in initial development between these ecosystems points to the important role early colonizers such as crustaceans and Chironomidae play in early development of these communities.

Does it take a community to save a species? Investigating community interactions among at-risk unionid species in the Great Lakes basin [Oral Presentation]

Roland Eveleens (Primary Presenter/Author)
Great Lakes Institute of Environmental Research, University of Windsor, eveleen@uwindsor.ca;

Todd J. Morris (Co-Presenter/Co-Author)
Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, todd.morris@dfo-mpo.gc.ca;

Catherine Febria (Co-Presenter/Co-Author)
University of Windsor, Catherine.Febria@uwindsor.ca;

Abstract: Freshwater unionid mussels contribute numerous ecosystem functions and interact with all trophic levels of a food web, organic matter, algae, invertebrates and fish. To date research on mussel species interactions has focused on mussel-host fish relationships and early life-stage (i.e., glochidial) processes. However, improved understanding of interactions across trophic levels could be critical in addressing declines in many unionid species. We explored community interactions between different mussel species, benthic macroinvertebrates and water quality indicators across the Sydenham River watershed in Ontario, Canada. Through partnerships with federal and local conservation authorities, we conducted a survey in the 2020 summer using a hybrid timed search/quadrat approach to quantify freshwater mussel communities and co-occurring macroinvertebrate taxa. Patterns of species co-occurrence were found across multiple gradients, with differences across sites and with waterway size. Some common mussel species were nearly ubiquitous, while other species were limited to few sites, including listed species at risk. Combining efforts across agencies bolstered existing datasets and added insight into species coexistence and potential indicator species. As these interaction types are infrequently considered in conservation, this will aid future freshwater mussel management efforts across multiple scales.

EAST OR WEST, NESTS ARE BEST: DRAMATICALLY DIFFERENT DRAGONFLY HABITATS HAVE SURPRISINGLY SIMILAR NESTEDNESS (NEATO!) [Oral Presentation]

Karen Gaines (Primary Presenter/Author)
University of Kansas, khgaines@hotmail.com;

Maria Aliberti-Lubertazzi (Co-Presenter/Co-Author)
RHODE ISLAND SCHOOL OF DESIGN, MALIBERT@RISD.EDU;

Abstract: Ecologists have long sought to explain species richness patterns in which less diverse habitat patches predictably contain only subsets of species found in more diverse communities. Although such nestedness patterns are sometimes observed locally, direct comparisons of analogous communities in contrasting ecosystems are uncommon despite representing excellent opportunities to test the generality of island biogeography theory predictions. To determine if larval odonate (dragonfly and damselfly) communities in dissimilar ecosystems exhibit similar richness patterns, we collected exuviae (larval exoskeletons) from 27 saline sinkholes in New Mexico and 21 freshwater ponds in Rhode Island. Nestedness analyses reveal that both systems support significantly nested larval communities and regression analyses suggest that species richness tends to increase with increasing pond size. However, the environmental filtering mechanisms driving these patterns appear to differ: species’ idiosyncratic water salinity tolerances and predation pressure from larger larval odonates are important in the desert sinkholes, while the degree of surrounding urbanization in the temperate pond system may drive those species distribution patterns. This study illustrates that superficially similar nestedness patterns in analogous systems may arise from very different local-scale environmental forces.

Evaluating impacts of fisheries management practices on a freshwater fish community through size spectrum modeling [Oral Presentation]

David Benoit (Primary Presenter/Author)
University of Toronto, d.benoit@mail.utoronto.ca;

Abstract: Historically, fisheries management has been based on maximum sustainable yield theory of individual fish stocks; however, this approach has long been criticized for its inability to capture species interactions and dynamics of non-target species. Ecosystem-based fisheries management (EBFM), a framework that emphasizes a multispecies perspective, has been proposed as a method to address these issues. Size spectrum models, which can be used to assess interactions between species and simulate community dynamics under various scenarios, present an opportunity to apply an EBFM approach to fisheries management through modeling. Although size spectrum models have successfully been applied to numerous marine ecosystems, their use in freshwater systems is limited. Here, we develop a multispecies size spectrum model for Lake Nipissing, a large, north temperate lake with an economically and culturally important Walleye (Sander vitreus) fishery in Ontario, Canada. Through our simulations, we evaluate the impacts of various fisheries management practices on population and community dynamics of both target and non-target species. In doing so, we highlight the potential of this approach in freshwater systems.

FOREST LOSS INCREASES COMPOSITIONAL UNIQUENESS OF STREAM COMMUNITIES, BUT SPECIES CONTRIBUTE TO BETA DIVERSITY AT BOTH EXTREMES OF THE LAND-USE GRADIENT [Oral Presentation]

Fabiana Schneck (Primary Presenter/Author)
Universidade Federal do Rio Grande - FURG, Brazil, fabiana.schneck@gmail.com;

Luis Mauricio Bini (Co-Presenter/Co-Author)
Universidade Federal de Goiás, Brazil, lmbini@gmail.com ;

Adriano Melo (Co-Presenter/Co-Author)
Universidade Federal do Rio Grande do Sul, Brazil, asm.adrimelo@gmail.com;

Danielle Petsch (Co-Presenter/Co-Author)
Universidade Estadual de Maringá, Brazil, danikpetsch@gmail.com;

Victor Saito (Co-Presenter/Co-Author)
Universidade Federal de São Carlos, Brazil, victor.saito@gmail.com;

Simone Wengrat (Co-Presenter/Co-Author)
Universität Konstanz, Germany, siwbio@gmail.com;

Tadeu Siqueira (Co-Presenter/Co-Author)
Universidade Estadual Paulista - UNESP, Brazil, tsiqueira@rc.unesp.br;

Abstract: We investigated the local contributions (LCBD) and the species contributions (SCBD) to beta diversity of stream benthic diatoms and insects over a gradient of land-use intensification, ranging from streams in pristine forest to agriculture catchments. We expected that LCBD would be negatively related to the percentage of forest cover in the catchment and positively related to uniqueness in stream environmental characteristics. We also expected that species with high SCBD would occur at the most degraded sites. We sampled 100 streams in southeast Brazil. Diatom and insect LCBD were negatively related to forest cover. Insects also showed a positive relationship with environmental uniqueness. We also found that SCBD of diatoms correlated positively with forest cover, but the inverse was found for insects. As forest cover was negatively correlated to uniqueness in land use, it is clear that biologically unique streams were those that deviated from the regional typical land cover. Moreover, our results indicate that the most important species to beta diversity may occur at both ends of the gradient in land-use intensity and, more importantly, diatoms and insects with the highest contribution may occur at opposite ends of the gradient.

FROM PERENNIAL TO EPHEMERAL: HYDROLOGIC GRADIENTS IN DESERT STREAMS STRUCTURE AQUATIC INVERTEBRATE COMMUNITIES ACROSS THE AMERICAN SOUTHWEST [Oral Presentation]

Angelika Kurthen (Primary Presenter/Author)
Oregon State University, kurthena@oregonstate.edu;

Tiffany Schriever (Co-Presenter/Co-Author)
Western Michigan University, tiffany.schriever@wmich.edu;

Richard VanDriesche (Co-Presenter/Co-Author)
Oregon State University, Richard - FW Van Driesche ;

Dave Lytle (Co-Presenter/Co-Author)
Oregon State University, lytleda@oregonstate.edu;

Abstract: Intermittent streams and rivers are hallmarks of arid-land and desert ecosystems. Within these systems, there is often a gradient of hydrology, from perennial to ephemeral reaches, linked to seasonality, which may vary across ecoregions. The goal of this study was to untangle the effects of basin-wide hydrology and seasonality on aquatic insect communities. In three major desert ecoregions that differ in rainfall patterns (Sonoran, Chihuahuan, and Mojave Deserts) we intensively sampled aquatic invertebrates in all habitats (perennial, intermittent, and ephemeral) in two replicate stream networks in two seasons (Spring, Fall) across two years (51 sample sites ). We deployed electrical resistance sensors to directly quantify reach-scale hydrology year- round. Preliminary results show drainages with a majority of intermittent sites (>50%) have a larger Chao community dissimilarity than drainages that were fully perennial. Understanding how changes in hydrology impact aquatic invertebrate communities provide insight to how stream ecosystems will respond to future climate changes.

HIGH SPECIES REPLACEMENT AT SMALL SPATIAL SCALES: LOCAL CONDITIONS DRIVE TURNOVER IN INTERDUNAL WETLAND MACROINVERTEBRATE COMMUNITIES [Oral Presentation]

Nicole Stewart (Primary Presenter/Author)
Western Michigan University, nicole.a77.thompson@wmich.edu;

Tiffany Schriever (Co-Presenter/Co-Author)
Western Michigan University, tiffany.schriever@wmich.edu;

Abstract: Environmental conditions and spatial processes structure communities, but the relative roles of these factors vary across the landscape, resulting in spatially variable biodiversity. Interdunal wetlands are nested within Lake Michigan’s coastal dune ecosystem and host abundant communities of aquatic macroinvertebrates. These wetlands contain previously undocumented aquatic macroinvertebrate diversity, are locally variable, and span a strong temperature and precipitation gradient across four degrees of latitude. To determine the relative roles of spatial processes and environmental conditions on alpha diversity patterns and community composition, we sampled 36 wetlands along the coastline and implemented abundance-based beta partitioning, multivariate, and species estimation analyses. Total estimated species richness was 115.69. Despite a short latitudinal gradient, we found a negative relationship between species richness and latitude (R2 = 0.11, P = 0.03). At local spatial scales, we found moderate to highly dissimilar communities structured by species replacement tracking local conditions (Mantel r = 0.329, P = < 0.01). This pattern was repeated along the coastline. Contrary to neutral theory, multiple-site Bray-Curtis dissimilarity did not increase with increasing spatial scale. Results suggest coastline connectivity and numerous protected areas are critical to maintain biodiversity in the dune ecosystem.

MACROINVERTEBRATE INTERACTIONS STIMULATE DECOMPOSITION IN WWTP EFFLUENT IMPACTED AQUATIC ECOSYSTEMS [Oral Presentation]

Gea van der Lee (Co-Presenter/Co-Author)
Wageningen Environmental Research, gea.vanderlee@wur.nl;

Ralf C.M. Verdonschot (Co-Presenter/Co-Author)
Wageningen Environmental Research, ralf.verdonschot@wur.nl;

Piet F.M. Verdonschot (Co-Presenter/Co-Author)
University of Amsterdam / Wageningen Environmental Research , piet.verdonschot@wur.nl;

Tom van der Meer (Primary Presenter/Author)
Wageningen Environmental Research, tom1.vandermeer@wur.nl;

Abstract: Aquatic ecosystems worldwide are impacted by an influx of nutrients and sludge particles from wastewater treatment plant (WWTP) effluents, leading to a degradation of benthic habitats and a loss of associated macroinvertebrate taxa. Hence, the few tolerant macroinvertebrate taxa remaining in these systems play an important role in the degradation of organic matter, and biotic interactions between these taxa may either affect the sludge degradation rate. Therefore, the aim of the present study was to examine if the interaction between asellids and tubificids, both abundant in WWTP effluent impacted systems, enhances the sludge degradation. Thus, growth and reproduction of both taxa, sludge degradation, and nutrient concentrations in the overlying water were measured in a 28-day laboratory experiment, subjecting WWTP sludge to 4 treatments; a control without macroinvertebrates, a tubificid, an asellid, and an asellid+tubificid treatment. Sludge degradation, phosphate concentration in the overlying water and asellid reproduction were enhanced when both taxa were jointly present, whereas tubificid growth and reproduction were hampered. Hence, our results suggest that the biotic interactions between these tolerant detritivores stimulate sludge degradation, and thus possibly mitigate the negative impacts of WWTP discharges on the benthic environment.

META-ANALYSIS OF FRESHWATER FISH COMMUNITY STRUCTURE USING CO-OCCURRENCE NULL MODELS: PATTERNS ACROSS HABITATS, CLIMATES, AND SPATIAL SCALES [Oral Presentation]

Xingli Giam (Co-Presenter/Co-Author)
University of Tennessee, xgiam@utk.edu;

Julian Olden (Co-Presenter/Co-Author)
University of Washington, olden@uw.edu;

Jerald Johnson (Co-Presenter/Co-Author)
Brigham Young University, jerry.johnson@byu.edu;

Trevor Williams (Primary Presenter/Author)
Brigham Young University, trevorjwilli@byu.edu;

Abstract: Numerous processes – particularly environmental filtering and predation – are important drivers of fish community assembly. Interestingly, a meta-analysis of species co-occurrence patterns (Gotelli and McCabe 2000) showed that fish were more randomly structured than other vertebrates, suggesting assembly rules may negligibly affect fish co-occurrence patterns. However, the sample size for fish communities in that study was relatively small, therefore it is unclear whether fish are indeed more randomly structured than other vertebrates. We conducted a meta-analysis of studies that used null models of species co-occurrence in freshwater fish to reassess the findings of Gotelli and McCabe and to understand how patterns of community structure vary across habitats, climates, and spatial scales. We found that freshwater fish communities show similar amounts of community structure as other vertebrate groups when comparing the standardized effect sizes of null model analyses. Furthermore, the strength of community structuring varies across habitat types and climates: communities in lotic habitats and temperate climates are more structured than communities in lentic habitats and tropical climates. Our results highlight the contingent nature of community assembly by showing how different processes are important in structuring communities across the globe.

META-ANALYSIS OF FRESHWATER POSITIVE INTERACTIONS REVEALS THE ROLE OF COMMON PARTICIPANTS, INVASIVE SPECIES, AND STRESS [Oral Presentation]

Lindsey Albertson (Primary Presenter/Author)
Montana State University , lindsey.albertson@montana.edu;

Michael MacDonald (Co-Presenter/Co-Author)
Montana State University, macdonald.mik@gmail.com;

Benjamin Tumolo (Co-Presenter/Co-Author)
Montana State University, bbtumolo@gmail.com;

Michelle Briggs (Co-Presenter/Co-Author)
Montana State University, michelle.briggs32@gmail.com;

Zachary Maguire (Co-Presenter/Co-Author)
Montana State University, zmag1988@gmail.com;

Sierra Quinn (Co-Presenter/Co-Author)
Montana State University, sierra.quinn15@gmail.com;

Jose Sanchez-Ruiz (Co-Presenter/Co-Author)
Montana State University, jas091988@gmail.com;

Jaris Veneros (Co-Presenter/Co-Author)
Montana State University, jaris.veneros@untrm.edu.pe;

Laura Burkle (Co-Presenter/Co-Author)
Montana State University, laura.burkle@montana.edu;

Abstract: Positive interactions between organisms impact populations, communities, and ecosystems. Appreciation of positive interactions, especially in marine and terrestrial ecosystems, has contributed to fundamental concepts such as the stress gradient hypothesis and niche construction. In freshwater ecosystems, however, it is not well understood how strong the roles of positive interactions are. We used meta-analysis to evaluate how positive interactions are studied in freshwater ecosystems by quantifying outcomes from 106 publications containing 340 total studies. The research was conducted in 26 countries on four continents. Research was most commonly conducted in lotic habitats and with mollusks as the facilitator. Positive associations stemmed from two primary mechanisms, habitat modification and resource augmentation, and habitat modification has stronger positive effects. Invasive facilitators had stronger positive effects on their beneficiaries than native facilitators. We found no evidence of stronger positive interactions in high stress treatments. Avenues for future research include understudied organisms, expanding studies investigating stress gradients, comparing the relative strength of positive interactions to negative ones, and developing hypotheses for how changes to positive interaction networks associated with the loss of key species or introduction of new species could have consequences for freshwater ecosystems.

Multiple predator effects among larval stages of pond-breeding salamanders [Oral Presentation]

Tom Anderson (Primary Presenter/Author)
Southern Illinois University Edwardsville, thander@siue.edu;

Jon Davenport (Co-Presenter/Co-Author)
Appalachian State University, davenportjm@appstate.edu;

Abstract: When multiple predators co-occur in a community, they can have either additive or non-additive impacts on prey survival. Non-additive impacts, or emergent multiple predator effects (MPEs), occur when foraging rates of combined predators cannot be predicted based on their individual foraging rates, resulting in either prey risk enhancement or reduction. We conducted several experiments to assess whether emergent MPEs occur between different species of larval salamanders, as well as how different factors (prey density and the occurrence of an additional top predator) may mediate emergent MPEs. Additionally, we experimentally tested how emergent MPEs affect the diversity of anuran prey assemblages. Across all three experiments, we found that larval salamanders had additive impacts on prey, rather than exhibit emergent MPEs. This occurred despite the different contexts under which we investigated MPEs. Furthermore, we found larval salamanders had additive impacts on prey diversity. Altogether these results suggest that emergent MPEs may not play a critical role in structuring predator-prey dynamics in this system, despite substantial a priori knowledge on larval aggression that would have suggested strong interference among predators.

PREDATION MEDIATES NEGATIVE CONSEQUENCES OF HABITAT SHIFTS IN POND ECOSYSTEMS [Oral Presentation]

Isaac Shepard (Primary Presenter/Author)
University of Maine, isaac.shepard@maine.edu;

Scott Wissinger (Co-Presenter/Co-Author)
Allegheny College, swissing@allegheny.edu;

Zach Wood (Co-Presenter/Co-Author)
University of Maine, zachary.t.wood@maine.edu;

Hamish Greig (Co-Presenter/Co-Author)
University of Maine, hamish.greig@maine.edu;

Abstract: Climate change is altering local environmental gradients and rearranging ecological communities. For example, species inhabiting temporary ponds may be forced into more permanent basins as temporary pond drying outpaces species’ development rates. However, the consequences of these localized habitat shifts for resident and range-shifting species are largely unknown. We used an in-situ field experiment to understand how competition and predation influence the demographic variables of two species of limnephilid caddisflies experiencing niche overlap as the temporary pond species is forced to use semi-permanent ponds more regularly. We found that competition between these two species is strong with significant reductions in survival for the resident species. Moreover, we found that competition greatly increased the variation in survival for the shifting species indicating that this interaction introduces instability into its population dynamics. However, we also found that Dytiscus beetle larva predators balance out these negative consequences by reducing both the strength of competition and the variation in survival for the shifting species. These results demonstrate the importance for maintaining diverse habitats with healthy populations of higher order predators to increase resilience against climate-change induced alterations to freshwater communities.

RESOURCE MODIFICATION BY STREAMBED ECOSYSTEM ENGINGEERS FACILITATES INVERTEBRATE COMMUNITY ASSEMBLY AND ECOSYSTEM FUNCTION [Oral Presentation]

Benjamin Tumolo (Primary Presenter/Author)
Montana State University, bbtumolo@gmail.com;

Lindsey Albertson (Co-Presenter/Co-Author)
Montana State University , lindsey.albertson@montana.edu;

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

Grace Davenport (Co-Presenter/Co-Author)
Amherst College, gdavenport21@amherst.edu ;

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

Abstract: Ecosystem engineers that alter resource availability can facilitate aggregations of other organisms with consequences for ecosystem functions. We conducted a mesocosm experiment that quantified how net-spinning caddisflies (Hydropsychidae) influence local food resources, macroinvertebrate density, and ecosystem respiration by building retreat structures made of organic materials and silk. We found that food resources, measured as particulate organic matter (POM), and macroinvertebrate density were 1.4X and 2X higher in the presence of caddisflies compared to controls, respectively. Furthermore, we show that macroinvertebrate density was 1.7X higher per given unit of POM in the presence of caddisflies compared to controls, suggesting that caddisflies may enhance the quality of POM for colonist consumers. Finally, we found that ecosystem respiration was 1.6X higher in the presences of caddisflies compared to controls, likely due to increased metabolic activity of invertebrates and heterotrophic microbes. Taken together, these results suggest that caddisfly engineering increases the quantity, and possibly quality, of resources, which leads to greater macroinvertebrate densities and increased ecosystem respiration. Our findings highlight how positive interactions through resource modification can have consequences for community assembly which can cascade to ecosystem functions related to carbon cycling.

Rethinking Biodiversity Patterns and Processes in Stream Ecosystems [Oral Presentation]

Matthew Green (Primary Presenter/Author)
University of California Riverside, mgree013@ucr.edu;

Kurt Anderson (Co-Presenter/Co-Author)
University of California, Riverside, kurt.anderson@ucr.edu;

David B. Herbst (Co-Presenter/Co-Author)
Institute of Marine Sciences, University of California Santa Cruz, and Sierra Nevada Aquatic Research Laboratory, University of California Santa Barbara, herbst@lifesci.ucsb.edu;

Marko Spasojevic (Co-Presenter/Co-Author)
University of California, Riverside, markos@ucr.edu;

Abstract: A major goal of community ecology is understanding the processes responsible for generating biodiversity patterns. In stream ecosystems, system specific frameworks have dominated research describing biodiversity change along river networks. However, support for these frameworks has been mixed and these frameworks have placed less emphasis on general mechanisms driving biodiversity. Here, we apply the Theory of Ecological Communities (TEC) framework to focus explicitly on core ecological processes structuring communities. Using a case study of stream invertebrates from alpine lake-stream networks, we tested the generality of stream and the TEC frameworks. Overall, we found support that biodiversity in lake-stream networks is structured along the river network, similar to well-studied streams, but lakes modify aspects of community structure. Despite support for the predicted biodiversity patterns, the mechanistic reasons hypothesized to structure biodiversity were only partially supported. Local diversity was structured by niche selection and ecological drift, where beta-diversity was influenced by dispersal and niche selection. By combining stream ecology frameworks with the TEC, we were able to mechanistically determine why data did and did not conform to predictions from stream ecology frameworks.

REVERBERATING EFFECTS OF RESOURCE EXCHANGES IN STREAM-RIPARIAN FOOD WEBS [Oral Presentation]

Scott Collins (Primary Presenter/Author)
Texas Tech University, Scott.Collins@ttu.edu;

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

Amy Marcarelli (Co-Presenter/Co-Author)
Michigan Technological University, ammarcar@mtu.edu;

Laura Felicetti (Co-Presenter/Co-Author)
Washington State University, Laurafelicetti@wsu.edu;

Scott Florin (Co-Presenter/Co-Author)
Washington State University, scottflorin@wsu.edu;

Mark Wipfli (Co-Presenter/Co-Author)
University of Alaska Fairbanks, mwipfli@alaska.edu;

Gregg Servheen (Co-Presenter/Co-Author)
Idaho Department of Fish and Game, greggservheen@idfg.gov;

Abstract: Fluxes of materials or organisms across ecological boundaries directly affect recipient food webs. Few studies have addressed how such direct responses in one ecosystem may, in turn, influence the fluxes to other habitats. As part of a large-scale experiment, we evaluated the hypothesis that the input of a marine-derived subsidy results in a complex array of resource exchanges between stream and riparian ecosystems as responses disperse across ecological boundaries. We found that salmon carcasses altered stream-riparian food webs by directly subsidizing multiple aquatic and terrestrial organisms (e.g., benthic insects, fish, terrestrial flies). Such responses further influenced food webs along indirect pathways, some of which spanned land and water. Subsidy-mediated feedbacks manifested when carcasses were removed to riparian habitats where they were colonized by carrion flies, some of which fell into the stream and acted as another prey subsidy for fishes. As the effects of salmon subsidies propagated through the stream-riparian food web, the sign of consumer responses was not always positive and appeared to be determined by the outcome of trophic interactions, such that localized trophic interactions within one ecosystem mediated the export of organisms to others.

Snow monkeys feed on riverine organisms [Oral Presentation]

Alexander Milner (Primary Presenter/Author)
University of Birmingham, a.m.milner@bham.ac.uk;

Laura Biessy (Co-Presenter/Co-Author)
Cawthron Institute, NZ, Laura.Biessy@cawthron.org.co.nz;

Susie Wood (Co-Presenter/Co-Author)
Cawthron Institute, Susie.Wood@cawthron.org.nz ;

Catherine Docherty (Co-Presenter/Co-Author)
University of Birmingham, catherine.l.docherty@gmail.com;

Masaki Takenaki (Co-Presenter/Co-Author)
National Institute for Basic Biology, takenaki@nibb.ac.jp;

Koji Tojo (Co-Presenter/Co-Author)
Biology Department, Faculty of Science, Shinshu University, Japan , ktojo@shinshu-u.ac.jp;

Abstract: The snow monkey (Macaca fuscata), native to the main islands of Japan, is the most northerly living non-human primate. In Kamikochi, our study area, snow monkeys live in one of the coldest areas of the world (winter -20-30 ° C and deep snowfall). Winter is a potential bottleneck season for food availability and snow monkeys can experience energy crises. We collected 38 fresh snow monkey winter faeces samples from 2017 to 2019 where e-DNA was extracted and sequences compared to the GenBank database. One species of freshwater fish Salmo trutta (the brown trout) was clearly identified with 100% sequence similarity. Two freshwater mollusc species present (Potamopyrgus antipodarum and Semisulcospira dolorosa) and five genera of insects were also detected, two being stoneflies (Nemoura fluva and Sweltsa sp). Snow monkeys utilize stream fauna to overwinter because they are unable to migrate across the steep mountains in mid-winter (>2500m of elevation) and an abundance of groundwater upwellings and active volcanoes ensure many streams are flowing allowing access to the monkeys for this food source. This is the first evidence of snow monkeys eating freshwater fauna.

Spatial heterogeneity in stream biofilm communities and organic matter processing in an agricultural stream network: Does groundwater play a role? [Oral Presentation]

Isabelle Lavoie (Co-Presenter/Co-Author)
Institut National de la Recherche Scientifique, Centre Eau Terre Environnement, isabelle.lavoie@ete.inrs.ca;

Clare Robinson (Co-Presenter/Co-Author)
Western University, crobinson@uwo.ca;

Jim Roy (Co-Presenter/Co-Author)
Environment and Climate Change Canada, jim.roy@canada.ca;

Shayla Kroeze (Co-Presenter/Co-Author)
Western University & Canadian Rivers Institute, skroeze@uwo.ca;

Nicole Gotkowski (Co-Presenter/Co-Author)
Western University & Canadian Rivers Institute, ngotkows@uwo.ca;

Max Boreux (Co-Presenter/Co-Author)
Western University, mboreux@uwo.ca;

Adam Yates (Co-Presenter/Co-Author)
University of Waterloo, adam.yates@uwaterloo.ca;

Lauren Banks (Primary Presenter/Author)
University of Waterloo, l2banks@uwaterloo.ca;

Abstract: Groundwater contributions to stream water can affect the availability of nutrients and moderate temperature, influencing spatial and temporal heterogeneity in environmental conditions. However, the role of groundwater as a driver of spatial and temporal heterogeneity in ecological conditions within stream networks is not well understood. To evaluate the association between groundwater and ecological communities and processes, we assessed stream biofilm communities (biomass and diatom taxonomy) and cellulose decomposition over 4 seasons in 19 reaches that exhibit variable groundwater input within an agricultural stream network in Ontario, Canada. Radon and temperature were measured as proxies for groundwater input. Seasonal variations in water temperatures were shown to structure diatom assemblage and cellulose decomposition at the network scale. Moreover, there were clear seasonal patterns taxa succession observed in the diatom assemblages that transcended groundwater influence. However, within season assessments of biofilms did not reveal any associations with proxies of groundwater inputs for algal biomass, diatom taxonomy or cellulose decomposition observed in individual reaches. Reach- and patch-scale studies will be undertaken to further evaluate the role of groundwater influence on ecological conditions in streams.

THE ROLES OF LOCAL, REGIONAL AND SPATIAL FACTORS IN SHAPING ZOOPLANKTON METACOMMUNITIES: IMPLICATIONS FOR THE BIOASSESSMENT OF LAKES IN NORTHERN GREAT PLAINS [Oral Presentation]

Buddhine Meegahage (Primary Presenter/Author)
University of Regina, buddhine.meegahage@gmail.com;

Bjoern Wissel (Co-Presenter/Co-Author)
University of Regina, bjoern.wissel@uregina.ca;

Erin Hillis (Co-Presenter/Co-Author)
University of Windsor- GLIER, erin.hillis7@gmail.com ;

Caroline Ofosu (Co-Presenter/Co-Author)
University of Regina, carolineofosu@gmail.com;

Anas Mohamed Usoof (Co-Presenter/Co-Author)
University of Toronto, anas007m@gmail.com;

Kyle Hodder (Co-Presenter/Co-Author)
University of Regina, kyle.hodder@uregina.ca;

Zoraida Rivera (Co-Presenter/Co-Author)
University of Regina, Zoraida.Quinones@uregina.ca;

Abstract: In the face of climate warming and intensifying land-use changes affecting the lakes of northern Great Plains, a better understanding of the processes regulating the lake biota is important. While local environmental factors were traditionally considered as sole determinants of lake community assembly, the importance of regional factors and dispersal processes have received limited attention. Based on a synoptic survey of 78 prairie lakes across Saskatchewan, we evaluated the relationships of local (water chemistry, morphometric, watershed characteristics), regional (climate, land use) and spatial factors with zooplankton species composition. To test and quantify the relative importance of these factors, we performed ordination analyses, spatial modeling, and variation partitioning. Significant associations between species composition and local factors including salinity, productivity, maximum depth, hydraulic conductivity, percentage shrub-land, and percentage broadleaf forest in the watershed were detected. In addition, species compositional variation was significantly related to regional differences in urbanization and agricultural intensity, indicating the potential of zooplankton communities to reflect the effects of regional land-use changes. Variation partitioning indicated a considerable importance of spatially contingent, dispersal processes in structuring zooplankton communities. Thus, dispersal processes may partially offset zooplankton community responses to environmental changes.

TINY BUBBLES (IN THE MUD): BIOTURBATION FREQUENCY ALTERS METHANE EMISSIONS FROM RESERVOIR SEDIMENTS [Oral Presentation]

Michael Booth (Primary Presenter/Author)
University of Cincinnati, michael.booth@uc.edu;

Megan Urbanic (Co-Presenter/Co-Author)
University of Cincinnati, urbanimn@mail.uc.edu;

Xia Wang (Co-Presenter/Co-Author)
University of Cincinnati, wang2x7@ucmail.uc.edu;

Jake J. Beaulieu (Co-Presenter/Co-Author)
United States Environmental Protection Agency, beaulieu.jake@epa.gov;

Abstract: Bioturbation of sediment shifts biogeochemical conditions and can physically release sediment-bound bubbles containing greenhouse gases (GHGs). However, variation in disturbance frequency may modify the rate and composition of resulting GHG emissions, potentially due to shifts in microbial composition or activity. We hypothesized that an intermediate disturbance frequency would result in the greatest methane (CH4) releases due to mechanical release of trapped bubbles, while frequent disturbance would result in greater diffusive carbon dioxide (CO2) releases relative to CH4, as sediment conditions shift from anaerobic to aerobic. We tested our hypothesis in laboratory mesocosms containing reservoir sediment and measured GHG emission (ebullition and diffusion) rates under experimental disturbance regimes. An intermediate frequency of disturbance (7 days) produced the highest total GHG emission rate (driven by CH4 ebullition), while the most frequent disturbance interval (3 days) and least frequent interval (0 days) reduced overall GHG emissions relative to weekly disturbance. For all disturbance treatments, the majority of ebullition occurred during disturbance events, suggesting release of bubbles is an important emission mechanism. The frequency of disturbance has variable effects on GHG emissions and may explain conflicting results in prior studies of bioturbation.

TRANSBOUNDARY ASSESSMENT OF BENTHIC MACROINVERTEBRATE DIVERSITY PATTERNS IN TRIBUTARIES OF THE RED RIVER BASIN [Oral Presentation]

Edward Krynak (Primary Presenter/Author)
University of Waterloo, ekrynak@gmail.com;

Robyn Martens (Co-Presenter/Co-Author)
University of Waterloo, rd2martens@uwaterloo.ca;

Robert B. Brua (Co-Presenter/Co-Author)
Environment and Climate Change Canada, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, bob.brua@canada.ca;

R. William Bouchard, Jr. (Co-Presenter/Co-Author)
Minnesota Pollution Control Agency, Will.Bouchard@state.mn.us;

Aaron Larsen (Co-Presenter/Co-Author)
North Dakota Department of Environmental Quality, allarsen@nd.gov;

Joshua Wert (Co-Presenter/Co-Author)
North Dakota Department of Environmental Quality, jewert@nd.gov;

Adam Yates (Co-Presenter/Co-Author)
University of Waterloo, adam.yates@uwaterloo.ca;

Abstract: The Red River Basin is a key transboundary watershed shared by Canada and the USA. Tributary monitoring efforts have been ongoing for over a decade in the three main jurisdictions that comprise the Basin (Manitoba, Minnesota, North Dakota), but there has not been a transboundary assessment of the available data. We initiate this process by conducting a basin-wide, biogeographical assessment of stream benthic macroinvertebrate assemblages using data from over 1000 stream samples. Initial assessments include analyses to determine geographical patterns of alpha and beta-diversity across the region and among six major ecoregions. Preliminary results indicate a significant amount of homogeneity in assemblage composition, possibly a result of the widespread agricultural activity in much of the Red River Basin. Further assessments will be conducted to test hypotheses about the role of land use on diversity patterns and to link benthic invertebrate communities with stream water chemistry and habitat measures. Furthermore, we will explore the spatial relationship among communities and its influence on taxonomic turnover among sample sites. Findings will provide critical insight towards improved collaborative management of tributaries throughout the Red River Basin.

AN ONGOING STUDY INTO MACROINVERTEBRATE COMMUNITY RECOLONIZATION IN AN INTERMITTENT OZARK STREAM [Poster Presentation]

Henry Priest (Primary Presenter/Author)
Missouri State University , Priest1016@live.MissouriState.edu;

Hannah Robinson (Co-Presenter/Co-Author)
Missouri State University , Bartron19@live.missouristate.edu;

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

Abstract: Intermittent streams make up the majority of the total stream length in the USA, but they are understudied, especially in temperate regions like the Ozark Highlands, where they are common and typically have diverse macroinvertebrate communities. We are examining macroinvertebrate recolonization patterns following the dry season in an intermittent Ozark stream that typically loses surface flow 4-5 months annually. Recolonization sources include perennial seeps, small in-channel pools maintained through drought, streambed sediments, and nearby perennial streams. Starting October 2020 (end of dry season), we have collected macroinvertebrates monthly in four longitudinally distributed reaches spanning approximately 700m between a small upstream seep and the confluence with a perennial, 2nd-order stream. Early results show that diverse EPT taxa colonized quickly following flow resumption in November. Recolonist communities were substantially different from perennial mainstem communities, a result that suggests most taxa recolonize the benthos from local, in-channel sources, including several Trichoptera from the upstream seep and Plecoptera and Ephemeroptera from streambed sediments. Our study is the first to thoroughly examine benthic community recolonization in the Ozarks ecoregion and will provide data crucial to conservation and management of common but underappreciated intermittent streams.

AQUATIC MACROINVERTEBRATE COMMUNITY DYNAMICS IN RESPONSE TO HIGH DENSITY OF INVASIVE SALMONIDS IN MULTIPLE RIVERS OF SUB-ANTARCTIC CHILE [Poster Presentation]

Sabrina Moore (Primary Presenter/Author)
University of North Texas, sabrinamoore2@my.unt.edu;

Tamara Contador (Co-Presenter/Co-Author)
Universidad de Magallanes, tamara.contador@umag.cl;

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

Abstract: Salmonid fishes are recognized globally as being among the most widespread and harmful invasive taxa. Today, they are widely distributed across the southern cone of the Americas including in many of the region’s most remote and previously pristine ecosystems. The Róbalo and Bronces rivers are located on the north coast of Navarino Island (55°S) of the Cape Horn Archipelago and Biosphere Reserve of southern Chile. The rivers support naturalized populations of salmonid fishes originating from aquaculture escapes and introductions elsewhere. It is thought that three salmonid species, brook trout (Salvelinus fontinalis), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) are impacting the instream macroinvertebrate communities but to date, negative interactions have not been fully shown. Macroinvertebrates were collected from three conditions, No Fish, Salmonids, and Salmonids-Galaxids using quantified d-frame sampling. The stocking densities were calculated for each fish population from electrofishing data. The community composition was significantly different between sites. The differences were due to salmonid presence and environmental variables. Salmonid invasions in freshwater alter instream communities and negatively affect nutrient cycling. This study will aid in the understanding the ecosystem functioning in the sub-Antarctic region.

CONSEQUENCES OF RIPARIAN DEFORESTATION ON DETRITUS-BASED FOOD-WEBS IN STREAMS [Poster Presentation]

Rebecca Oester (Primary Presenter/Author)
University of Zürich, rebecca.oester@uzh.ch;

Paula dos Reis Oliveira (Co-Presenter/Co-Author)
University of Amsterdam, p.c.dosreisoliveira@uva.nl;

Florian Altermatt (Co-Presenter/Co-Author)
Eawag, Swiss Federal Institute of Aquatic Science and Technology, florian.altermatt@eawag.ch;

Marcelo Moretti (Co-Presenter/Co-Author)
University of Vila Velha, msmoretti@gmail.com;

Andreas Bruder (Co-Presenter/Co-Author)
Institute of Earth Sciences, University of Applied Sciences and Arts of Southern Switzerland, Canobbio, Switzerland, andreas.bruder@supsi.ch ;

Abstract: Detritus-based food-webs in streams govern important ecosystem functions and services such as decomposition of leaf litter from the riparian vegetation. This process is mainly controlled by the interactive effects of aquatic hyphomycetes and invertebrate shredders. The relative importance of these decomposer groups and the resource quality however differ strongly between tropical and temperate regions. Land-use, such as agriculture, may compromise food-webs and decomposer biodiversity differently in tropical and temperate streams. In this project, we aim to elucidate the consequences of landscape transformation and to disentangle biodiversity effects on ecosystem functioning in headwater streams in Switzerland (Prealps) and Brazil (Atlantic Forest). To do so, we assess leaf litter decomposition, biodiversity (leaf litter, aquatic hyphomycetes, shredders, predators) and detrital food-web configuration in forested and deforested sites. Preliminary results indicate that the influence of the landscape on decomposition rates is dependent on abiotic and biotic conditions. Our project will contribute to the understanding of environmental controls on the functioning of detritus-based food-webs in streams and the links between riparian and stream ecosystems in both tropical and temperate regions.

FRESHWATER LOTIC COMMUNITIES UPSTREAM AND DOWNSTREAM OF A LOW HEAD DAM BEFORE AND AFTER REMOVAL [Poster Presentation]

Zachary Bragg (Co-Presenter/Co-Author)
Ohio Northern University, z-bragg@onu.edu;

Garrett Duktig (Co-Presenter/Co-Author)
Ohio Northern University, g-duktig@onu.edu;

Everett Meredith (Co-Presenter/Co-Author)
Ohio Northern University, e-meredith@onu.edu;

Tyler Tanto (Co-Presenter/Co-Author)
Ohio Northern University, t-tanto@onu.edu;

Devon Jackson (Co-Presenter/Co-Author)
Ohio Northern University, Department of Biological & Allied Health Sciences, d-jackson.5@onu.edu;

Robert Verb (Co-Presenter/Co-Author)
Ohio Northern University, r-verb@onu.edu;

Leslie Riley (Primary Presenter/Author)
Ohio Northern University, l-riley.1@onu.edu;

Abstract: Low head dams can negatively impact lotic systems by interrupting community connectivity, trapping sediments and altering hydrologic patterns. Removal of dams can restore natural flow regimes, but effects on stream communities have been mixed, limiting our understanding of ecosystem recovery. The objective of this study is to document changes in stream communities before and after removal of a low head dam. The Allentown Dam, removed in August 2020, was located in the Ottawa River (Maumee River Watershed) in northwest Ohio. For two years before removal (2018, 2019), upstream and downstream communities (periphyton, macroinvertebrates, fish) and selected physicochemical parameters were monitored, along with communities at two reference sites. In 2020, the same sites were sampled post-removal and will be resampled again in 2021. Preliminary results indicate that benthic riffle communities, along with physicochemical parameters were similar upstream and downstream of the dam. Conversely, fish biomass, fish diversity and the percentage of predatory fish were higher downstream of the dam. Results suggest the dam prevented upstream movement of some fish, but did not significantly impact benthic communities. Ongoing analyses will also include comparisons to stream communities post-dam removal.

THE EFFECT OF PHYSIOGRAPHIC REGIONS ON BENTHIC RIFFLE COMMUNITIES IN THE KOKOSING RIVER (OHIO) [Poster Presentation]

Makaiah Thomas (Co-Presenter/Co-Author)
Ohio Northern University, m-thomas.15@onu.edu;

Madeline Williams (Co-Presenter/Co-Author)
Ohio Northern University , m-williams.18@onu.edu;

Leslie Riley (Co-Presenter/Co-Author)
Ohio Northern University, l-riley.1@onu.edu;

Robert Verb (Co-Presenter/Co-Author)
Ohio Northern University, r-verb@onu.edu;

Kourtney Craft (Primary Presenter/Author)
Ohio Northern University , k-craft@onu.edu;

Abstract: Geology, physiographic history, and land use are among the most important factors influencing benthic community structure and distribution in lotic systems. During the Pleistocene Epoch, large sheets of ice altered much of the surface of Ohio by depositing large quantities of till across much of the state’s landscape while other areas were not impacted. The objective here was to examine whether glacial history impacted the quality of riffle habitats and associated benthic communities in a river in central Ohio. The Kokosing River transitions through several physiographic regions including the Till Plains, the Glaciated Allegheny Plateau, and the Unglaciated Allegheny Plateau. Periphyton, macroinvertebrates, fish, and selected physicochemical parameters were collected in riffle habitats at nine sites, traversing two of these regions (Till Plains and Glaciated Allegheny Plateau). Analyses indicated that specific conductance and pH were both higher in the Till Plains and could be a result of increased groundwater contributions from limestone aquifers prevalent in this region. Current analyses will document changes in the benthic community and further investigation next year will expand comparisons across a third physiographic region, the Unglaciated Allegheny Plateau.

THE EFFECT OF TWO-STAGE DITCH CHANNEL MORPHOLOGY ON BENTHIC COMMUNITY STRUCTURE WITHIN THE BLANCHARD RIVER WATERSHED [Poster Presentation]

Colin Light (Co-Presenter/Co-Author)
Ohio Northern University, c-light@onu.edu;

Connor Ney (Co-Presenter/Co-Author)
Ohio Northern University, Department of Biological & Allied Health Sciences, c-ney@onu.edu;

Lauren Govekar (Co-Presenter/Co-Author)
Ohio Northern University, l-govekar@onu.edu;

Janet Deardorff (Co-Presenter/Co-Author)
Ohio Northern University, j-deardorff@onu.edu;

Chad Carroll (Co-Presenter/Co-Author)
Hancock Soil & Water Conservation District, c-carroll@onu.edu;

Leslie Riley (Co-Presenter/Co-Author)
Ohio Northern University, l-riley.1@onu.edu;

Robert Verb (Primary Presenter/Author)
Ohio Northern University, r-verb@onu.edu;

Abstract: Two primary threats to northwest Ohio watersheds are hydrologic variation and nutrient enrichment. Two-stage ditches are one attempt to mitigate these threats and are designed to reduce discharge and sediment loading into primary watershed tributaries. Previous studies have documented that ditches can also serve as habitat for organisms and can make substantial contributions to diversity within watersheds, but the effect of two-stage ditch morphology on benthic communities is not well known and, in at least one study, appears to not be important. Thus, the focus of this investigation was to determine if benthic community composition in a two-stage ditch differed from traditional open ditch habitats (Blanchard River Watershed, Ohio). Multivariate analysis indicated that two stage ditch benthic communities were significantly different from that of the traditional, open ditch sites. Two-stage ditch sites were characterized by lower turbidity, lower water temperature and a detritivore-dominant community, while open ditch sites were dominated by macroalgae and herbivorous snails. Two-stage ditch sites had a closed canopy due to increased plant biomass within the ditch, leading to less light availability and possibly contributing to lower water temperatures when compared to open ditch sites.