SFS Annual Meeting

6/06/2024  |   13:30 - 13:45   |  Freedom Ballroom F

The Role of Contaminant Risk Landscapes in the Anthropocene Human mobilization of chemical pollution across the planet coupled with widespread landcover change are markers of our current geologic era, the Anthropocene. However, changes in contaminant mobilization and land cover are generally studied independently and at different spatial scales, even though contaminants and how their risks are manifested differ across the landscape. Landscape alteration plays a critical role in the likelihood that a particular place will capture, sequester, or transform contaminants, ultimately impacting their bioavailability to humans and wildlife. This presentation will introduce a conceptual framework, the ‘contaminant risk landscape,’ that merges perspectives from geochemistry, landscape ecology, and toxicology to understand the transport, fate, and impact of toxic contaminants in the natural world. Successful management and mitigation of contaminant toxicity may be improved through merging these diverse perspectives and traditions to achieve effective solutions.

Jacqueline Gerson (Primary Presenter/Author), Michigan State University, gersonja@msu.edu;

Collin Eagles-Smith (Co-Presenter/Co-Author), US Geological Survey, ceagles-smith@usgs.gov;

David Walters (Co-Presenter/Co-Author), United States Geological Survey, waltersd@usgs.gov;

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6/06/2024  |   13:45 - 14:00   |  Freedom Ballroom F

Effects of forest defoliation by insects on in-stream carbon and mercury cycling Insect defoliation is a widespread forest disturbance in Canada, and has the potential to alter terrestrial carbon inputs to streams and their incorporation by consumers. Although defoliation by spruce budworm (Choristoneura fumiferana) is a natural disturbance with importance to forest succession, the magnitude and duration of outbreaks are increasing, and there is a growing need to understand the downstream consequences of these outbreaks. A recent outbreak in Québec, eastern Canada, provided the unique opportunity to examine stream food web responses across watersheds experiencing a range of defoliation. We examined 12 second or third order streams to assess whether food web structure and methylmercury (MeHg) cycling were affected. In 2019 and 2020, food sources, several macroinvertebrate taxa across functional feeding groups, and fish were collected and analyzed for stable isotopes (d13C, d15N) and MeHg or total Hg (fish only). MixSIAR models and hierarchical partitioning analyses showed that consumers from streams with greater watershed defoliation had lower reliance on autochthonous carbon, despite increased algal production. In addition, mercury levels in predatory invertebrates and brook trout were predicted mainly by quantity and quality of dissolved organic carbon (DOC), not watershed defoliation. Results suggest that forest disturbances from spruce budworm affect carbon inputs and use by stream consumers that, in turn, indirectly affect mercury bioaccumulation in headwater streams.

Kaiying S. Ju (Co-Presenter/Co-Author), McMaster University, juk@mcmaster.ca;

Karen Kidd (Primary Presenter/Author), McMaster University, karenkidd@mcmaster.ca;

Carl Mitchell (Co-Presenter/Co-Author), University of Toronto Scarborough, carl.mitchell@utoronto.ca;

Erik Emilson (Co-Presenter/Co-Author), Great Lakes Forestry Centre, Canadian Forest Service, erik.emilson@canada.ca;

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6/06/2024  |   14:00 - 14:15   |  Freedom Ballroom F

CHEMICAL, PHYSICAL AND BIOLOGICAL FACTORS INFLUENCING MERCURY CONCENTRATIONS IN AGE-0 BROOK TROUT IN COLD-WATER STREAMS OF THE NORTHEASTERN U.S. In the northeastern U.S., multiple trajectories of environmental change, operating via multiple mechanisms at a range of ecosystem levels, have the potential to ameliorate or exacerbate bioaccumulation of toxic metals such as mercury (Hg) in freshwater food webs. To help elucidate these pathways and potential outcomes, we sampled age-0 brook trout (Salvelinus fontinalis) and aquatic macroinvertebrates from 60 small cold-water streams across the northeastern U.S., covering a wide gradient of watershed and water quality characteristics associated with Hg bioaccumulation using a Structural Equation Model (SEM) approach to assess the strength of direct and indirect pathways. Our models indicate a strong direct pathway associated with increased dissolved organic carbon (DOC) leading to increased Hg in aquatic macroinvertebrates and extending to age-0 brook trout. Further, negative relationships between Hg in fish and macroinvertebrate abundance and brook trout biomass are consistent with lower bioaccumulation in more productive habitats (bloom dilution). Finally, lower fish Hg in sites where stream temperatures were closer to optimal temperatures for brook trout growth, along with larger individual size, was consistent with a reduction in Hg bioaccumulation with increased fish growth efficiency (somatic growth dilution). The strong dependence of these pathways on climate-associated ecosystem changes indicates substantial but complex impacts of regional climate change on bioaccumulation in stream ecosystems.

Ethan Rutledge (Primary Presenter/Author), University of Massachusetts-Amherst, earutledge@umass.edu;

Keith Nislow (Co-Presenter/Co-Author), Northern Research Station, U.S.D.A. Forest Service, University of Massachusetts Amherst, keith.nislow@usda.gov;

Matthew Fuller (Co-Presenter/Co-Author), USDA Forest Service, matthew.fuller@usda.gov;

Heather Bortolussi (Co-Presenter/Co-Author), University of Massachusetts-Amherst, hbortolussi@umass.edu;

Celia Chen (Co-Presenter/Co-Author), Dartmouth College, celia.y.chen@dartmouth.edu;

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6/06/2024  |   14:15 - 14:30   |  Freedom Ballroom F

Selenium impacts on methylmercury retention across mayfly life stages depend on dietary methylmercury exposure levels Though high concentrations of mercury and selenium are individually toxic to organisms, it is hypothesized that high levels of environmental Se can reduce Hg bioaccumulation and biomagnification in aquatic food webs. This potential interaction between mercury and selenium has been under-studied in aquatic macroinvertebrates, particularly in relation to their complex life histories. We examined the proposed effect of selenium on methylmercury accumulation, along with the transfer of methylmercury, between four life stages for a parthenogenetic mayfly (Neocloeon triangulifer). We found support for the mercury-selenium interaction hypothesis, but it is context-specific. At high dietary methylmercury, elevated aqueous selenium lowered mayfly methylmercury concentrations; however, at low methylmercury treatments, there was no effect of selenium on mayfly methylmercury accumulation. Additionally, though we found higher methylmercury concentrations in terrestrial adult stages compared to aquatic larval stages at both methylmercury treatment levels, the cumulative life history transfer factor (LHTF; the ratio of methylmercury in the final adult imago stage compared to late instar larvae) differed by treatment. The LHTF was constant for all aqueous selenium exposure levels at high dietary methylmercury treatment (likely due to impacts of selenium on methylmercury uptake and loss) but increased with aqueous selenium exposures at low dietary methylmercury treatments (likely due to impacts of selenium on methylmercury uptake only). These results suggest predators of adult mayflies would be exposed to greater methylmercury than predators of larval mayflies for all selenium and methylmercury levels, but that the ameliorative effect of selenium on methylmercury accumulation only occurs at high dietary methylmercury levels.

Jacqueline Gerson (Co-Presenter/Co-Author), Michigan State University, gersonja@msu.edu;

Collin Eagles-Smith (Co-Presenter/Co-Author), US Geological Survey, ceagles-smith@usgs.gov;

Emily Bernhardt (Co-Presenter/Co-Author), U.S. Geological Survey, rdorman@usgs.gov ;

David Walters (Primary Presenter/Author), United States Geological Survey, waltersd@usgs.gov;

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6/06/2024  |   14:30 - 14:45   |  Freedom Ballroom F

Conservative transport of selenium from the Elk River (Canada) to the Columbia River and potential biogeochemical explanations Coal-mining operations in the Elk River Valley, British Columbia (BC), Canada, have increased total selenium (Se) concentrations in downstream waters, including the transboundary Koocanusa Reservoir (Montana, USA and BC). To evaluate the potential for long-range transport of Se, we assessed patterns in Se concentrations and loads at five sites downstream of mining activity on the Elk, Kootenay, and Columbia Rivers in BC relative to those at a Kootenay River site in BC that is unaffected by the Elk River mines (ERMs). Flow-normalized Se concentrations have increased at all sites downstream of ERMs, with percent increases ranging from 89% closest to ERMs in the Elk River to 35% 575 km downstream in the Columbia River (2005-2021). In contrast, no trends were observed at the Kootenay River site unaffected by ERMs (2005-2017). Concentrations and 5-year mean annual loads (2013-2017) at the five sites downstream of ERMs were up to an order of magnitude greater than at the site unaffected by ERMs. These loads were stable for 383 km from ERMs to the Kootenay River near Creston (BC) and increased by 53% below the Kootenay-Columbia River confluence, which suggests Se losses through two riverine reservoirs were minimal and increased loads downstream can largely be attributed to natural Se weathering. The persistence of increasing trends in Se concentrations, elevated Se loads, and elevated Se concentrations 575 km downstream of ERMs suggest that predominantly alkaline and oxidizing conditions promote conservative and long-range transport of Se through the Elk, Kootenay, and Columbia Rivers.

Madison Foster (Primary Presenter/Author), USGS WY-MT Water Science Center, mfoster@usgs.gov;

Meryl Storb (Co-Presenter/Co-Author), USGS WY-MT Water Science Center, mstorb@usgs.gov;

Johanna Blake (Co-Presenter/Co-Author), USGS New Mexico Water Science Center, jmtblake@usgs.gov;

Travis Schmidt (Co-Presenter/Co-Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;

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6/06/2024  |   14:45 - 15:00   |  Freedom Ballroom F

Integrated, multi-scale approaches to detecting long-term exposure of freshwater fish to selenium in the Koocanusa Reservoir This presentation will introduce results of integrated monitoring programs to assess chronic selenium exposure for freshwater fish at individual and population levels. Large-scale open-pit coal mining often degrades water quality, leading to severe disruption of aquatic ecosystems. In British Columbia, Canada, coal mine wastes leaching into the nearby Elk River are responsible for selenium-enriched waters entering the Koocanusa Reservoir at concentrations that exceed U.S. water-quality standards (0.8 µg/L from the US-Canada international boundary to the Libby Dam). The buildup of selenium concentrations in reservoir water at levels potentially toxic to fish and other wildlife may contribute to the observed declines in certain fish populations. To improve understanding of the ecological impacts of selenium and associated environmental threats in the Koocanusa Reservoir, a comprehensive description of the fate and impact of selenium and mercury contamination on wild fish is needed. To this purpose, we implemented multi-scale (temporal and biological) and multi-tissue (metabolically active and inert; soft and archival) approaches using isotopic (87Sr/86Sr), elemental (ICP-MS and X-ray fluorescence microscopy), and biological analyses. We aim to i) assess selenium exposure levels in environmental and biological compartments between 1984-2022, ii) identify sources and pathways of fish exposure, iii) trace the migration of individual fish, and iv) evaluate the physiological responses and cascading effects at higher levels of biological organization in fish exposed to selenium and mercury.

Noelie Molbert (Primary Presenter/Author), University of Connecticut, noelie.molbert@uconn.edu;

James Dunnigan (Co-Presenter/Co-Author), Montana Fish Wildlife and Parks, jdunnigan@mt.gov;

Frederick Feyrer (Co-Presenter/Co-Author), California Water Science Center, U.S. Geological Survey, ffeyrer@usgs.gov;

Rachel Johnson (Co-Presenter/Co-Author), Center for Watershed Sciences, University of California Davis, rachel.johnson@noaa.gov;

Travis Schmidt (Co-Presenter/Co-Author), USGS WY-MT Water Science Center, tschmidt@usgs.gov;

Ashley Bussell (Co-Presenter/Co-Author), United States Geological Survey, abussell@usgs.gov;

Molly Moloney (Co-Presenter/Co-Author), USGS, mmoloney@usgs.gov;

Samuel Webb (Co-Presenter/Co-Author), Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, samwebb@slac.stanford.edu;

Jessica Brandt (Co-Presenter/Co-Author), University of Connecticut, jessica.brandt@uconn.edu;

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