5/25/2016  |   10:30 - 10:45   |  307

HIGH-THROUGHPUT AMPLICON SEQUENCING AND STREAM BENTHIC BACTERIA: IDENTIFYING THE BEST TAXONOMIC LEVEL FOR MULTIPLE-STRESSOR RESEARCH Recent advances in molecular techniques allow studying entire microbial communities in their environment, with a resolution down to Operational Taxonomic Units (OTUs). Should we therefore investigate OTUs, or can we simply look at common phyla? We evaluated this for multiple-stressor effects of four agricultural stressors on stream bacteria in outdoor mesocosms: the nitrification inhibitor dicyandiamide (DCD), fine sediment, nutrient enrichment, and flow velocity reduction (simulating water diversion). Benthic bacteria were assessed using amplicon sequencing. Effects on diversity and common taxa at phylum, order, genus and OTU level indicate that agricultural stressors can strongly influence stream bacterial communities. DCD was the most pervasive stressor, affecting community evenness and prevalence of almost all common taxa, followed by sediment and velocity reduction. Nutrient enrichment had little effect. Stressor pervasiveness and effect sizes were reasonably consistent across taxonomic levels. Taxa within the same genus or order often responded similarly. Community coverage decreased with taxonomic resolution (96% of all sequences for common phyla, 28% for common OTUs). Consequently, the order level may represent the best compromise between stressor sensitivity and coverage of entire bacterial communities.

Christoph Matthaei (Primary Presenter/Author), University of Otago, Dept of Zoology, New Zealand, christoph.matthaei@otago.ac.nz;


Romana Salis ( Co-Presenter/Co-Author), University of Otago, Dept of Zoology, New Zealand, romana.salis@otago.ac.nz ;


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 ;


Jeremy Piggott ( Co-Presenter/Co-Author), University of Otago, Dept of Zoology, New Zealand , jeremy.piggott@otago.ac.nz;


Tina Summerfield ( Co-Presenter/Co-Author), University of Otago, Dept of Botany, New Zealand, tina.summerfield@otago.ac.nz ;


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5/25/2016  |   10:45 - 11:00   |  307

ASSESSING CAUSALITY WITH PROBABILISTIC REASONING AND GRAPHICAL MODELS: A CASE STUDY IN APPALACIAN SURFACE MINING The environmental impacts of extensive surface mining for Appalachian coal have garnered increased attention in recent years. A number of investigators have demonstrated strong associations between elevated ionic concentrations below mountaintop mines and the extirpation of stream macroinvertebrates. Yet despite more than a dozen studies, debate continues to rage in judicial and regulatory proceedings. At issue are the multiple potential mechanisms of impairment linking mining activities to biotic response. Skeptics argue that alterations of physical habitat and temperature regimes can and do confound observed patterns of biotic impairment below mountaintop mines. Using graphical models to represent patterns of dependence in causal networks, I perform the observational equivalent of experimental manipulations with standard probabilistic reasoning to test empirical evidence supporting both sets of claims. Both constraint-based and Bayesian learning algorithms revealed strong support for the causal role of elevated ionic concentrations. I illustrate how relatively simple analytical methods can nonetheless generate important insight into the drivers and mechanisms of biotic response and suggest that similar approaches might be used to understand other complex syndromes associated with human activity.

Matthew Baker (Primary Presenter/Author), University of Maryland Baltimore County, mbaker@umbc.edu;


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5/25/2016  |   11:00 - 11:15   |  307

MULTIPLE STRESSORS PREDICT FUNGAL INFECTION IN A DECLINING CALIFORNIA FROG DURING AN HISTORIC DROUGHT The foothill yellow-legged frog (Rana boylii), a California endemic dwelling exclusively in flowing water, is gone from half its former range. In rivers with dams, where declines are most pronounced, frogs face multiple stressors including altered thermal regimes and proIiferation of introduced predators. It is unknown whether the pathogenic chytrid fungus (Batrachochytrium dendrobatidis; Bd), which has caused amphibian declines globally, could be contributing to decline of R. boylii. In 2013, we observed a Bd outbreak and die-off in the Alameda Creek watershed in the San Francisco Bay Area, which is the first documented occurrence of such an event for R. boylii. To determine which factors predict infection, we conducted Bd sampling for two years following the outbreak in stream reaches that varied with respect to flow regulation. Using mixed effects modeling, we found that season, stream-flow, life-stage, non-native American bullfrogs, and drought associated concentrated densities, are important predictors of infection. We conclude that Bd can pose a previously unrecognized threat to R. boylii, and that future hypolimnetic releases intended to benefit salmonid restoration may increase Bd infection intensity and prevalence.

Sarah Kupferberg (Primary Presenter/Author), Questa Engineering, skupferberg@gmail.com;


Andrea Adams ( Co-Presenter/Co-Author), University of California Santa Barbara, andrea.adams@lifesci.ucsb.edu ;


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5/25/2016  |   11:15 - 11:30   |  307

MACROINVERTEBRATE RESPONSES TO MULTIPLE STRESSORS IN A LOWLAND STREAM NETWORK Worldwide, freshwater ecosystems are being destroyed, fragmented, modified, and overexploited to support the needs of a growing human population. These multiple stressors impact aquatic biodiversity and ecosystem function across space and time, although a clear mechanistic understanding is still lacking. Here, we examined macroinvertebrate responses among streams in a Swiss lowland catchment encompassing a gradient of multiple stressors. Clear compositional changes were observed as anthropogenic stressors increased from least-impacted to agricultural and urbanized sites. Taxonomic diversity was lowest at sites with morphological and water quality impairment (agricultural sites), whereas taxonomic identity (susceptible vs. generalist species) mainly changed due to water quality degradation (agricultural and urban sites) based on the SPEAR (pesticides) index. This result was reflected in a simplification in macroinvertebrate trophic structure along the stressor gradient. At a site impacted with wastewater treatment effluent, stable isotope analysis (?13C, ?15N) revealed trophic shifts in primary consumers that corresponded to changes in available food resources. The combination of analyses, including stable isotopes, provided a better mechanistic understanding of community and population responses to multiple stressors in this human-dominated river network.

Chris Robinson (Primary Presenter/Author), Eawag, robinson@eawag.ch;


Simone Baumgartner ( Co-Presenter/Co-Author), EAWAG, simone_baumgartner@gmx.ch;


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5/25/2016  |   11:30 - 11:45   |  307

MAPPING WATERSHED INTEGRITY FOR THE CONTERMINOUS UNITED STATES Watersheds provide a variety of ecosystem services valued by society. Production of these services is sensitive to watershed alteration by human activities. Flotemersch and others (2015), defined watershed integrity (WI) as the “capacity of a watershed to support and maintain the full range of ecological processes and functions essential to the sustainability of biodiversity and of the watershed resources and services provided to society.” They argue that six key functions must be present for a watershed to have integrity: hydrologic regulation, regulation of water chemistry, sediment regulation, hydrologic connectivity, temperature regulation, and habitat provision. We developed and mapped an index of WI for the conterminous USA based on these six key functions by incorporating human landscape stressors from the EPA’s StreamCat dataset, that have been shown to degrade key functions in watersheds. The index is mapped at 1:100,000 scale at the stream catchment resolution, and provides a consistent way to compare WI across the Nation. Specific factors that highly influence WI scores signal effective management approaches for restoration, protection and restoration of watersheds.

Darren Thornbrugh (POC,Primary Presenter), ORISE c/o US EPA, Western Ecology Division, Corvallis, OR , thornbrugh.darren@epa.gov;


Scott Leibowitz ( Co-Presenter/Co-Author), US EPA, Pacific Ecological Systems Division, Corvallis, OR, leibowitz.scott@epa.gov;


Ryan Hill ( Co-Presenter/Co-Author), US Environmental Protection Agency, hill.ryan@epa.gov;
Ryan Hill is an aquatic ecologist with the U.S. EPA Office of Research and Development. He is interested in how watershed conditions drive differences in freshwater diversity and water quality across the United States. He has worked extensively with federal physical, chemical, and biological datasets to gain insights into the factors affecting water quality and biotic condition of freshwaters across the conterminous US. He has also worked to develop and distribute large datasets of geospatial watershed metrics for streams and lakes for the Agency (EPA’s StreamCat and LakeCat datasets). Ryan completed his PhD in Watershed Ecology at Utah State University in 2013 with Dr. Chuck Hawkins. He was an ORISE postdoctoral fellowship at the U.S. EPA from 2014-2019 before joining the EPA in 2019.

Marc Weber ( Co-Presenter/Co-Author), US EPA, Pacific Ecological Systems Division, Corvallis, OR, weber.marc@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;


Joseph Flotemersch ( Co-Presenter/Co-Author), EPA, Flotemersch.Joseph@epa.gov;


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5/25/2016  |   11:45 - 12:00   |  307

UNDERSTANDING AGRICULTURAL LAND USE DISTURBANCE IN STREAMS: A COMPARISON OF ALGAE AND INVERTEBRATE MULTI-STRESSOR MODELS In 2013, the U.S. Geological Survey and the U.S. Environmental Protection Agency sampled 100 streams across 11 States in the Midwest corn belt of the U.S. Ecological condition of streams were assessed in relation to flow, suspended sediment, nutrients, major ions, 230 dissolved pesticides and degradates, and sediment-associated contaminants. Effects of various stressors on algae and macroinvertebrates assemblage metrics were assessed using boosted regression tree response models; final models had between 4 to 8 explanatory variables. Models were developed for four stressor categories one at a time and then in combination: geographic-based land use (GIS), habitat, nutrients, and contaminants (water and sediment), then all instream stressors (habitat, nutrients, contaminants combined) and GIS and instream stressors combined. Comparison of algal and invertebrate models are explored through model performance by stressor category, comparison of final explanatory variables and stressor assessment across the large agricultural gradient.

Ian Waite (Primary Presenter/Author), U.S. Geological Survey, Portland, OR, iwaite@usgs.gov;


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