5/22/2016  |   15:30 - 15:45   |  313

BIOGEOCHEMISTRY OF NATURAL STRESSORS IN FRESHWATER SEDIMENTS Potentially toxic sulfide, ammonia, and reduced iron occur naturally in freshwater sediments. Although these chemical stressors can accumulate to high concentrations in reducing environments, their roles in shaping ecosystem structure and function are sometimes overlooked. To assess the prevalence of toxic levels of sulfide, ammonia, and iron, we sampled sediments, pore waters, and surface waters from a biogeochemically diverse set of shallow (< 2 m deep) freshwater ecosystems in southwest Michigan and compared our measured concentrations to water quality criteria established by the U. S. Environmental Protection Agency (EPA) and to toxic thresholds in the published literature. In addition, we quantified a suite of geochemical parameters (e.g., major ions, total elemental content, acid volatile sulfide) to characterize the biogeochemical settings in which these natural stressors occur. The benthic environment of almost every freshwater ecosystem we measured was theoretically toxic or stressful to some component of aquatic life in some area or at some time. Organismal tolerances to chemical stressors vary, so the toxicant concentrations that we measured are likely shaping benthic ecological communities and influencing rates of ecosystem function.

Lauren Kinsman-Costello (Primary Presenter/Author), Kent State University, lkinsman@kent.edu;


Jonathan O'Brien ( Co-Presenter/Co-Author), Canisius College, obrien46@canisius.edu;


Stephen K. Hamilton ( Co-Presenter/Co-Author), Michigan State University & Cary Institute of Ecosystem Studies, hamilton@kbs.msu.edu;


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5/22/2016  |   15:45 - 16:00   |  313

PERIPHYTON PRODUCTIVITY AND METAL UPTAKE IN A MINING IMPACTED RIVER Rates of periphyton biomass accrual and metal uptake were examined using artificial substrate samplers along a metal concentration gradient in a mining-impacted river to 1) determine the extent to which metal exposure affects net productivity, 2) identify possible metal-related shifts in trophic state, and 3) assess contaminant transfer pathways to invertebrate consumers. Rates of biomass accrual decreased relative to unimpaired conditions in reaches with high ambient metal concentrations (water and sediments) and low nutrients; however, accrual rates increased in nutrient-enriched environments despite high metal concentrations. Spatial changes in stream trophy (autotrophy to heterotrophy) were weakly correlated with metal exposure gradients; however, heterotrophy increased markedly in response to decreased flow velocity and increased nutrient enrichment. Metal uptake in periphyton was rapid and reached steady-state concentrations within the first four days of growth and accrual. Examination of feeding trait states and metal bioaccumulation in stream invertebrates showed that metal uptake increased dramatically in organisms where feeding on epibenthic algae comprised even a small percentage of their overall feeding strategy.

Terry Short (Primary Presenter/Author), U.S. Geological Survey, Menlo Park, CA, tmshort@usgs.gov;


Michelle Hornberger ( Co-Presenter/Co-Author), U.S. Geological Survey, Menlo Park, CA, mhornber@usgs.gov;


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5/22/2016  |   16:00 - 16:15   |  313

ASSESSING THE COMBINED EFFECTS OF METAL CONTAMINATION AND SEDIMENT DEPOSITION ON BENTHIC INVERTEBRATE COLONIZATION The combined effects of sediment deposition and metal contamination can pose serious risks to aquatic ecosystems, particularly in mountainous regions. This research examines the effects of metal contamination and sediment infiltration on benthic invertebrate colonization at the North Fork of Clear Creek, a U.S. EPA Superfund site in Black Hawk, Colorado, USA. Metal-contaminated coarse and fine sediment was transported to an upstream reference site where the rate of colonization by benthic macroinvertebrates was observed for 30 days. In addition to the presence or absence of metal-contaminated sediment, results were interpreted using grain size, organic matter, and species traits. Abundance increased over time for all insect orders; however, these changes were much slower in treatments with metal-contaminated fine sediment. Further analysis indicates a need to focus on interpreting other abiotic variables and species traits when estimating stream recovery. In particular, colonization rate of dominant taxa should also be quantified when assessing ecosystem responses to stream restoration. This research has broad implications pertaining to management strategies and our understanding of benthic community recovery in impaired environments.

Brittanie Dabney (Primary Presenter/Author), Colorado State University, brittaniedabney@gmail.com;


Jacob Williamson ( Co-Presenter/Co-Author), Colorado School of Mines, jacwilli@mymail.mines.edu ;


James Ranville ( Co-Presenter/Co-Author), Colorado School of Mines, jranvill@mines.edu;


William Clements ( Co-Presenter/Co-Author), Colorado State University, william.clements@colostate.edu;


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5/22/2016  |   16:15 - 16:30   |  313

COUPLING GEOCHEMISTRY AND COMMUNITY ECOLOGY: EFFECTS OF NICKEL-CONTAMINATED SEDIMENTS ON BENTHIC MACROINVERTEBRATE COMMUNITIES Nickel in aquatic ecosystems can be toxic to aquatic invertebrates and impair ecological function and biodiversity. However, the cycling and toxicity of Ni is coupled to other elemental cycles. Solid-phase ligands such as organic carbon, metal sulfide, and metal oxide minerals can bind Ni and limit its bioavailability. Our study assessed Ni bioavailability in sediments exposed to effluent from mining operations by coupling sediment geochemical characteristics to the indigenous macroinvertebrate community. Benthic macroinvertebrates (identified to family) were collected at two pairs of reference and effluent-exposed sites, concurrently with intact sediment cores and overlying water samples. Effluent-impacted sites contained high concentrations of sediment Ni and sulfur. Total macroinvertebrate abundance did not significantly differ between sites, but mayfly (Hexagenia sp.) relative abundance significantly decreased with total Ni concentration at both mine locations. PCA explained 43% of community variation, and principal components related to sediment (total Ni, oxide-bound Ni) and water chemistry (conductivity, sulfate) explained variation in abundance of major taxa. Our results highlight the importance of considering coupled elemental cycles when predicting benthic invertebrate toxicity to sediment metals.

Raissa Mendonca (Primary Presenter/Author), Kent State University, rmarques@kent.edu;


David Costello ( Co-Presenter/Co-Author), Kent State University, dcostel3@kent.edu;


Christian Schlekat ( Co-Presenter/Co-Author), NiPERA, cschlekat@nipera.org;


Emily Garman ( Co-Presenter/Co-Author), NiPERA, egarman@nipera.org;


Jennifer Daley ( Co-Presenter/Co-Author), University of Michigan, jmdaley@umich.edu;


Michelle Hudson ( Co-Presenter/Co-Author), University of Michigan, shellhud@umich.edu;


G. Allen Burton ( Co-Presenter/Co-Author), University of Michigan, burtonal@umich.edu;


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5/22/2016  |   16:30 - 16:45   |  313

CONTAMINANTS IN TIME AND SPACE: MOUNTAINTOP MINING IMPACTS ON STREAM HYDROLOGY, BIOGEOCHEMISTRY AND MACROINVERTEBRATES Mountaintop mining for coal substantially alters the landscapes of Central Appalachia by depositing large volumes of shattered bedrock into headwater valleys. Mining’s physical alteration to the land changes both the hydrology and biogeochemistry of freshwater ecosystems downstream. These watersheds have streams with elevated concentrations of sulfate, magnesium, calcium, bicarbonate, selenium and other ions leading to a 10-20 fold increase in mean annual specific conductance compared to unmined watersheds. These changes to water chemistry cause marked declines in macro-invertebrate diversity. We explored the temporal variation of mining contaminants in streams and its impact on macro-invertebrate abundance and diversity. We measured discharge and specific conductance every ten-minutes for 1.5 years in 4 streams with a range of mining from 0-99%. Our analysis shows that mined watersheds have much higher baseflow discharges in late summer than unmined watersheds. Pollution concentrations are highest during this baseflow period, and coincide with significant loss of macroinvertebrate diversity. Elevated late-summer baseflow in mined watersheds effectively extends the reach of mining contaminants farther downstream, impacting macroinvertebrates in watersheds with relatively small mining extent upstream.

Matthew Ross (Primary Presenter/Author), Colorado State University, mrvr@rams.colostate.edu;


Fabian Nippgen ( Co-Presenter/Co-Author), Duke University, fabian.nippgen@gmail.com;


Kristofor Voss ( Co-Presenter/Co-Author), Regis University, kvoss@regis.edu;


Brian McGlynn ( Co-Presenter/Co-Author), Duke University, brian.mcglynn@duke.edu;


Emily Bernhardt ( Co-Presenter/Co-Author), Duke University, ebernhar@duke.edu;


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5/22/2016  |   16:45 - 17:00   |  313

STRESSED FRESHWATER SYSTEMS: SSRIS (ANTIDEPRESSANTS) AFFECT STREAM ECOSYSTEM FUNCTION AT ENVIRONMENTALLY-RELEVANT CONCENTRATIONS Pharmaceuticals are important contaminants of concern in aquatic environments. One class of anti-depressant drugs, SSRIs are now detected in surface waters worldwide; however, the ecological impacts of SSRIs are not well understood. We conducted a 21d artificial stream experiment exposing leaf packs that were pre-colonized in a headwater stream. We used fine and coarse mesh bags to obtain leaf packs with and without invertebrates. Leaf packs and un-colonized rocks were added to artificial streams amended with environmentally realistic concentrations of SSRIs (20ng/L - 20ug/L). Biofilm colonization on rocks was affected by SSRIs; GPP was 60% lower on rocks in SSRI streams compared to controls. SSRIs did not affect community respiration on leaves, however, excluding invertebrates increased CR by 76% in invertebrate excluded leaf packs irrespective of treatment. The low concentration of SSRI (20ng/L of fluoxetine) led to earlier dipteran emergence compared to the control and 20ug/L treatments. These findings suggest that exposure to low concentrations of fluoxetine appears to affect aquatic biota, indicating that these compounds are not necessarily toxic, but may have the capacity to disrupt ecosystem processes.

Erinn Richmond (POC,Primary Presenter), Monash University, erinn.richmond@monash.edu.au;


Emma Rosi ( Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, rosie@caryinstitute.org;


Ross M. Thompson ( Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, ross.thompson@canberra.edu.au;


Michael Grace ( Co-Presenter/Co-Author), Monash University , michael.grace@monash.edu;


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