SFS Annual Meeting

6/04/2024  |   15:30 - 15:45   |  Freedom Ballroom F

Assessment of the status of freshwater biodiversity across Finland using bioassessment data Biodiversity in freshwaters has declined globally more than in any other ecosystem. Despite the decline, systematic data-driven assessments of freshwater biodiversity are lacking, hindering effective management. We are using monitoring and survey data of benthic invertebrate, diatom, phytoplankton or macrophyte communities from >2500 streams and lakes, collected across Finland during past 20 years, to assess status of freshwater biodiversity across Finland. Following Hawkins & Yuan (2016, Freshwater Science), we compare current observed frequencies of taxa to expected frequencies of taxa in near-natural conditions, the latter estimated from outputs of RIVPACS-type multi-taxon distribution models. For stream macroinvertebrates, we found significant, up to 50% declines in regional biodiversity with often marked decline in common taxa. The extent of taxa loss (or gain) varied among regions, land use types, water body types and biotic groups. This type of multitaxon assessments of biodiversity provide key information to more effectively implement policies (e.g. in European Union Water Framework Directive, Habitats Directive, Biodiversity Strategy, and Nature Restoration Law) aiming to halt freshwater biodiversity loss.

Jukka Aroviita (Primary Presenter/Author), Finnish Environment Institute, jukka.aroviita@syke.fi;

Anna Suuronen (Co-Presenter/Co-Author), Finnish Environment Institute, anna.suuronen@syke.fi;

Heikki Mykrä (Co-Presenter/Co-Author), Finnish Environmental Institute, heikki.mykra@syke.fi;

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6/04/2024  |   15:45 - 16:00   |  Philadelphia Ballroom

Using joint species distribution models to quantify potential biotic interactions among lotic fish assemblages of the contiguous United States Quantifying the influence of environmental factors on species distributions can elucidate their ecological requirements and potential response to anthropogenic disturbance. Single species distribution models are commonly used to quantify taxon-environment relationships but do not account for biotic interactions (e.g. competition, predation, mutualism). Joint species distribution models (JDSMs) are a multivariate extension that overcome this challenge by modeling all taxa in an assemblage simultaneously and explicitly accounting for associations between species. We compiled occurrence data for ~200 fish species at 3,865 sites surveyed by U.S. Environmental Protection Agency’s National Rivers and Streams Assessment. We then used JDSMs to quantify taxon-environment relationships and pairwise associations. These models accurately characterized fish assemblages (AUC > 0.7). Gradients of specific conductance, average maximum air temperature, discharge and substrate diameter were important variables for explaining species occurrences. In addition, we found several significant associations indicating that certain species co-occur more or less than expected from environmental conditions. Leveraging these associations, we used conditional prediction to assess the potential effects of removing non-native fishes. Interestingly, removing non-native fish could either increase or decrease native taxa richness, depending on the site and region. We demonstrate that data collected for monitoring purposes provide unparalleled opportunities to quantifying species’ relationships with key environmental factors and assessing potential biotic interactions across a large spatial extent. The views expressed in this presentation are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.

Darin Kopp (Primary Presenter/Author), U.S. Environmental Protection Agency, Kopp.Darin@epa.gov;

John Stoddard (Co-Presenter/Co-Author), U.S EPA, Office of Research and Development, Pacific Ecological Systems Division, Corvallis, OR, Stoddard.John@epa.gov;

Alan Herlihy (Co-Presenter/Co-Author), Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, OR, alan.herlihy@oregonstate.edu;

David Peck (Co-Presenter/Co-Author), U.S EPA, Office of Research and Development, Pacific Ecological Systems Division, Corvallis, OR, peck.david@epa.gov;

Philip Kaufmann (Co-Presenter/Co-Author), U.S EPA, Office of Research and Development, Pacific Ecological Systems Division, Corvallis, OR, Kaufmann.Phil@epa.gov;

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6/04/2024  |   16:00 - 16:15   |  Philadelphia Ballroom

Continental-scale diversity patterns in periphytic diatoms Biodiversity is decreasing globally because of human activities, and a clear understanding of how changes in environmental conditions affect biodiversity would be useful for environmental managers. Total taxon richness is one component of biodiversity, and in streams, changes in diatom richness have been associated with human activities. Here, we examine the drivers of stream diatom richness at a continental scale using data collected by the US EPA’s National Rivers and Streams Assessment. We focused on estimating the effects of natural and anthropogenic environmental gradients on diatom richness and asked whether these patterns were similar when richness was measured with traditional morphological identifications or measured with metabarcoding data. We also considered the effects of spatial scale by estimating effects on richness averaged among neighboring stream reaches. Metabarcoding data provide a more complete census of taxa at a site, but when richness computed from metabarcoding data are scaled appropriately, we observed that many relationships between environmental conditions and richness were similar whether estimated using morphological or metabarcoding data. We further found that naturally varying environmental gradients accounted for most of the variance in total richness, and that computing richness at different spatial scales altered the relationships with environmental gradients.

Lester Yuan (Primary Presenter/Author), U.S. Environmental Protection Agency, yuan.lester@epa.gov;

Richard Mitchell (Co-Presenter/Co-Author), U.S. Environmental Protection Agency, mitchell.richard@epa.gov;

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6/04/2024  |   16:15 - 16:30   |  Philadelphia Ballroom

RECOVERY HAS COME TO A HALT: LONG TERM ANALYSES OF CADDISFLY TRENDS Worldwide, insect populations showed severe declines because of anthropogenic stressors such as pollution, habitat destruction and increased temperatures. To halt declines of freshwater, clean water legislation was launched globally. The subsequent water quality improvements allowed the recovery of freshwater biodiversity to some extent, but, this came to a halt, with abundance and diversity currently stagnating or even declining. We hypothesise that the recovery of freshwater insects is hampered by species specific responses to multiple stressors in systems which are only moderately restored. Therefore, we aimed to reveal long-term trends in aquatic insect diversity and abundance, and analyse the potential of species-specific traits to explain the observed patterns. Trichoptera were selected as a model organism group. For the Netherlands a dataset with exceptional long temporal (>40 years) coverage and a fine spatial resolution was available. Based on this data Trichoptera richness and abundances were modelled with a novel combination of linear and non-linear techniques to derive species-specific changes in abundances which were linked to species traits to uncover species-specific sensitivities. Our results showed a significant increase in abundance and richness from 1980 to 2009-2013, after which recovery of abundance and richness plateaued or even decreased. Species with stable and declining abundance trends had significantly higher climate change vulnerability while, in contrast, improving species had lower climate change vulnerability and further benefited from local restoration measures. It was concluded that further recovery of freshwater biodiversity requires substantial efforts to combat the deterioration of only moderately restored aquatic ecosystems.

Elmar Becker (Primary Presenter/Author), Institute for Biodiversity and Ecosystem Dynamics - University of Amsterdam, e.becker@uva.nl;

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

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

Arie Vonk (Co-Presenter/Co-Author), University of Amsterdam, Institute of Biodiversity and Ecosystem Dynamics, J.A.Vonk@uva.nl;

Michiel Kraak (Co-Presenter/Co-Author), Institute of Biodiversity and Ecosystem Dynamics, M.H.S.Kraak@uva.nl;

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6/04/2024  |   16:30 - 16:45   |  Philadelphia Ballroom

Continental patterns of homogenization and differentiation of stream fish communities within and among the three dimensions of diversity Biotic homogenization is the loss of beta diversity due to nonnative introductions and extirpations of unique species. Changes in beta diversity can provide evidence for changes in community assembly processes. More information on community assembly processes can be gained by decomposing beta diversity into taxonomic, functional, and phylogenetic diversity. Stream fishes are an ideal system to study community assembly processes due to a high degree of habitat heterogeneity, endemism, and phylogenetic diversity. This study seeks to determine if the introduction of nonnative species has led to (1) homogenization/differentiation of stream fish communities within three dimensions of beta diversity and (2) the alteration of key beta diversity dimension relationships, thus providing evidence of altered community assembly processes. Stream fish community occurrence data for the conterminous United States was separated into two species pools: A native-only species pool and a full species pool which represented the community before and after nonnative introductions. Beta diversity was calculated for each species pool using the Sorensen Dissimilarity Index for taxonomic beta diversity and PhyloSor Index for functional and phylogenetic beta diversity. If mean beta diversity was lower in the contemporary pool, then homogenization had occurred due to nonnative introductions. Correlation between beta diversity dimension was calculated using Mantel correlations and bootstrapping was used to compare differences between species pools. A change in correlation coefficients would indicate that fundamental diversity relationships have changed over time, providing evidence for a change in community assembly processes.

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

Luke Bower (Co-Presenter/Co-Author), Clemson University, lmbower@g.clemson.edu;

Troy Farmer (Co-Presenter/Co-Author), Clemson Univerity, tmfarme@clemson.edu;

Stephen Midway (Co-Presenter/Co-Author), Louisiana State University, smidway@lsu.edu;

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

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6/04/2024  |   16:45 - 17:00   |  Philadelphia Ballroom

Flow variability and river network position drive temporal beta diversity and functional change in California, USA macroinvertebrate communities Disturbances and dispersal are both common ecological factors that influence taxonomic and functional community composition. Disturbances may act as filters that select for particular functional traits, whereas habitat connectivity may facilitate quick recovery of taxa through dispersal. In river networks, both disturbances and dispersal connectivity can be strongly influenced by network position. While previous studies have shown that network position contributes to community dissimilarity across space, the influence of network position on community dissimilarity across time remains understudied. We asked whether the degree to which different components of temporal biodiversity change are influenced by river network position and the level of flow disturbance. We utilized macroinvertebrate community data collected and archived through the California, USA Surface Water Ambient Monitoring Program, specifically focusing on 145 sites with multi-year sampling. In contrast to previous studies using Strahler stream order as a proxy for community connectivity, we calculated network-based metrics of closeness and betweenness centrality to provide a more specific measure of connectivity to river habitat. We found that isolation in river networks produced greater temporal changes functional composition and species richness, while flow variability increased variability in functional composition and abundance-based beta diversity. Additionally, we found that flow variability, not network location, most strongly influenced the functional redundancy in communities despite strong network position effects on taxonomic changes. Our study sheds light on how spatial mechanisms influence patterns of temporal change and the value of long-term monitoring in understanding spatiotemporal dynamics in freshwater communities.

Ryan Conway (Co-Presenter/Co-Author), University of California, Riverside, rconw002@ucr.edu;

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

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

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

Chris Swan (Co-Presenter/Co-Author), University of Maryland-Baltimore County, chris.swan@umbc.edu;

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