SFS Annual Meeting

5/23/2019  |   14:00 - 14:15   |  151 G

INTERACTIVE EFFECTS OF FLOW REGIME ALTERATION AND PROPAGULE PRESSURE IN DRIVING LARGE-SCALE PATTERNS OF FISH INVASION Anticipating how human activities may influence biodiversity replacement across large spatial scales requires understanding the mechanisms behind biological invasions. Both enhanced dispersal (propagule pressure) and flow regime alteration (novel niches) can promote the establishment and spread of non-native species, and ecological theory predicts that these mechanisms could interact locally to induce rapid community disassembly. However, empirical research has largely focused on these mechanisms individually. Here we developed a framework to evaluate how niche opportunities arising from hydrologic alteration, and propagule pressure, jointly control riverine fish invasions across the conterminous United States. Building on extensive biodiversity records and long-term (1987-2016) time-series of streamflow across 1,148 sub-watersheds, we showed that species invasion is highly non-random. Human-induced shifts towards less variable, more seasonal, and more predictable flow regimes have interacted with high levels of propagule pressure to alter the taxonomic and functional composition of fish assemblages. Our results contradict the notion that non-native species patterns are primarily driven by introduction effort—by altering the abiotic template, human activities promote aquatic invasions in complex, yet predictable ways. These findings highlight the potential of coordinated flow strategies to restore biodiversity in running waters.

Lise Comte (Co-Presenter/Co-Author), Conservation Science Partners, lise@csp-inc.org;


Ted Grantham (Co-Presenter/Co-Author), University of California, Berkeley, tgrantham@berkeley.edu;


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


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5/23/2019  |   14:15 - 14:30   |  151 G

SPECIES PAIRS ASSOCIATIONS, NULL MODLES, AND TESTS OF MECHANISMS STRUCTURING ECOLOGICAL COMMUNITIES Diamond’s assembly rules sparked a series of studies that have either challenged or corroborated his ideas about how natural communities are structured. However, most of these studies have focused on the role of competition and whether the entire species community is non-randomly structured. An alternative way to determine the community structure is to understand the patterns observed in the association of each pair of species. We examined hypotheses of whether there are significant non-random relationships in species pairs of fishes and whether these relationships are consistent across different watersheds. Using incidence matrices, we show many pairs of species exhibit non-random relationships in their patterns of co-occurrence. Although some species pairs do not co-occur in some watersheds due to biogeographic differences, many of these significant relationships are consistent across watersheds as shown in our meta-analysis. Our work both extends methodological approaches to testing the assembly of ecological communities, but also demonstrates that these temperate lake fish communities show strong evidence of repeatable, non-random composition.

Donald Jackson (Primary Presenter/Author), University of Toronto, don.jackson@utoronto.ca;


Ruben Coredero (Co-Presenter/Co-Author), University of Toronto, r.corderoalarcon@mail.utoronto.ca;


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5/23/2019  |   14:30 - 14:45   |  151 G

INCORPORATING NETWORK CONNECTIVITY INTO STREAM CLASSIFICATION FRAMEWORKS ABSTRACT: River classification frameworks are important tools for conserving aquatic resources; they simplify landscape complexity and inform management objectives across river networks. Despite their utility, most classification frameworks have not incorporated network relationships. In this study, we take a novel approach to stream classification by developing a 2-level classification framework for South Carolina rivers and streams. The level-1 classification will use spatially constrained clustering techniques to classify river valley segments according to geomorphic and regional climatic characteristics. A level 2 classification will add network connectivity parameters to the aforementioned approach (e.g. D-link, confluence symmetry ratio, etc.). Each classification will be validated and tested using data from the South Carolina Department of Natural Resources Stream Assessment (SCSA) and Small River Assessment (SRA) datasets, containing over 500 sites and 101 fish species. We expect our results to highlight the importance of incorporating network topology into a stream classification, and to provide an adaptive tool for the management of riverine ecosystems.

Mark C. Scott (Co-Presenter/Co-Author), South Carolina Department of Natural Resources, scottm@dnr.sc.gov;


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


Colby Denison (Primary Presenter/Author), Clemson University, cdeniso@g.clemson.edu;


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5/23/2019  |   14:45 - 15:00   |  151 G

AN INVESTIGATION OF SPATIAL COMPLEXITY AND DIVERSITY OF TERRESTRIAL INSECTIVORES IN A RIVER-FLOODPLAIN METACOMMUNITY Despite their disproportionate importance to the maintenance of biodiversity, river-floodplains are among the most imperiled ecosystems on the planet. Natural river-floodplain dynamism creates and maintains a complex mosaic of habitats which can sustain a diverse array of animals, both aquatic and terrestrial, with varying life-history traits and habitat requirements. One mechanism by which diversity of terrestrial insectivores may be maintained is through asynchronous patterns of insect emergence that result from patchiness within the landscape. We quantified richness and abundance of insectivorous arthropods, bats, and birds across a mosaic of 7 habitats that varied in physical characteristics (e.g., temperature, flow, and connectivity regime) on a floodplain of the Snake River in southeastern Idaho. Here, we present results from a ‘thought-experiment’ whereby we assessed insectivores in a metacommunity framework by randomly and sequentially aggregating assemblages from distinct habitat patches. As insectivore communities associated with each habitat patch were combined into successively larger and more complex metacommunities, we observed that richness increased to create a more diverse assemblage than was found in any habitat alone. These findings further elucidate the potential consequences of river-floodplain homogenization for biodiversity and species conservation.

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


Jade Ortiz (Primary Presenter/Author), Idaho State University, ortijade@isu.edu;


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