A. Robin Stewart
Robin Stewart is a Research Hydrologist for the USGS Water Resources Mission Area.
Robin Stewart has been a research hydrologist with U.S. Geological Survey's National Research Program (NRP) in Menlo Park since 2003. She received an undergraduate degree in Biology from the University of Victoria, British Columbia Canada in 1991 and a PhD in ecotoxicology from the University of Manitoba in 1998. Immediately following this she pursued a postdoctoral appointment with Canada's Department of Fisheries and Oceans in 1998 evaluating the fate and transport of organic contaminants during the 1997 Red River Flood. In the spring of 1999 she began her postdoctoral research with the USGS National Research Program.
For the past twenty years Robin Stewart's research has focused on identifying and understanding processes influencing the fate and bioavailability of selenium (Se), mercury (Hg), and organic contaminants in food webs across a range of aquatic environments including estuaries (San Francisco Bay and Puget Sound), rivers (Manitoba/North Dakota, Oregon, Wisconsin and Florida), lakes (Manitoba and Ontario), and tidal rivers and reservoirs (California). Through a combination of field-based process studies, in situ monitoring of key biomonitors over short-term (<3 years) and long-term (>10 years) time series, biodyanamic modeling and knowledge gained through laboratory-based studies of physiological uptake she strives to identify critical processes controlling contaminant bioaccumulation in nature.
Science and Products
Mercury cycling, bioaccumulation, and risk across western North America: a landscape scale synthesis linking long-term datasets
Fish Tissue Analysis Results, Koocanusa Reservoir, Montana, 2021
Mercury and selenium chemical characteristics and speciation data of bird, fish, and earthworm tissues
Data for monitoring trace metal and benthic community near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California (ver 2.0, November 2022)
Selenium concentrations in tissues of the cyprinid Sacramento Splittail of the San Francisco Estuary (2010-11 and 2017)
Knowledge gaps and opportunities in water-quality drivers of aquatic ecosystem health
Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2020
Using tissue cysteine to predict the trophic transfer of methylmercury and selenium in lake food webs
Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2019
Demethylation of methylmercury in bird, fish, and earthworm
Lifetime chronicles of selenium exposure linked to deformities in an imperiled migratory fish
Resolving selenium exposure risk: Spatial, temporal, and tissue-specific variability of an endemic fish in a large, dynamic estuary
Nutrients mediate the effects of temperature on methylmercury concentrations in freshwater zooplankton
Mercury methylation and bioaccumulation in Sinclair Inlet, Kitsap County, Washington
Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2017
Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2016
A practical method for the determination of total selenium in environmental samples using isotope dilution-hydride generation-inductively coupled plasma-mass spectrometry
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
- Science
Mercury cycling, bioaccumulation, and risk across western North America: a landscape scale synthesis linking long-term datasets
Mercury (Hg) is a serious environmental problem that is impacting ecological and human health on a global scale. However, local and regional processes are largely responsible for producing methylmercury, which drives ecological risk. This is particularly true in western North America where the combination of diverse landscapes, habitat types, climates, and Hg sources may disproportionally impact t - Data
Fish Tissue Analysis Results, Koocanusa Reservoir, Montana, 2021
Montana Fish, Wildlife, and Parks (MT FWP), in collaboration with the United States Geological Survey (USGS) Wyoming-Montana Water Science Center (WY-MT WSC), Montana Department of Environmental Quality (MDEQ), and the United States Environmental Protection Agency (USEPA) collected fish from the Koocanusa Reservoir in 2021 for tissue analysis. Fish tissue collected included muscle, eggs, liver, anMercury and selenium chemical characteristics and speciation data of bird, fish, and earthworm tissues
Birds (Clark's grebe, Aechmophorus clarkii; Forster's Tern, Sterna forsteri), fish (Peacock bass, Cichla temensis, Cichla monoculus; Pescada, Plagioscion squamosissimus) and earthworms were analyzed for selenium, total mercury, and methyl mercury concentration and mercury speciation. A Clark's grebe was collected from Lake Berryessa (California, United States) in September 2012. A Forster's Tern wData for monitoring trace metal and benthic community near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California (ver 2.0, November 2022)
Trace-metal concentrations in sediment and in the clam Limecola petalum (World Register of Marine Species, 2020; formerly reported as Macoma balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat located 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San FranSelenium concentrations in tissues of the cyprinid Sacramento Splittail of the San Francisco Estuary (2010-11 and 2017)
Estuaries provide critical habitat for a vast array of fish and wildlife but are also a nexus for core economic activities that mobilize and concentrate contaminants that can threaten aquatic species. Selenium (Se), an essential element and potent reproductive toxin, is enriched in parts of the San Francisco Estuary (SFE) to levels known to cause toxicity, yet the risk of Se to species that inhabi - Publications
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Knowledge gaps and opportunities in water-quality drivers of aquatic ecosystem health
This report identifies key scientific gaps that limit our ability to predict water quality effects on health of aquatic ecosystems and proposes approaches to address those gaps. Topics considered include (1) coupled nutrient-carbon cycle processes and related ecological-flow-regime drivers of ecosystem health, (2) anthropogenic and geogenic toxin bioexposure, (3) fine sediment drivers of aquatic eNear-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2020
Trace-metal concentrations in sediment and in the clam Limecola petalum (World Register of Marine Species, 2020; formerly reported as Macoma balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer (km) south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San FrancisAuthorsDaniel J. Cain, Marie-Noële Croteau, Janet K. Thompson, Francis Parchaso, A. Robin Stewart, Emily L. Zierdt Smith, Kelly H. Shrader, Le H. Kieu, Samuel N. LuomaUsing tissue cysteine to predict the trophic transfer of methylmercury and selenium in lake food webs
The biomagnification of toxic methylmercury (MeHg) and selenium (Se) through aquatic food webs using nitrogen stable isotopes (δ15N) varies among ecosystems but underlying mechanisms are yet unexplained. Given the strong links between MeHg and thiol-containing amino acids and proteins containing selenocysteine, our hypothesis was that cysteine content is a better predictor of MeHg and Se transferAuthorsJennifer C Thera, Karen A. Kidd, Robin Stewart, Robert F Bertolo, Nelson J. O'DriscollNear-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2019
Trace-metal concentrations in sediment and in the clam Limecola petalum (formerly reported as Macoma balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the dataAuthorsDaniel J. Cain, Marie-Noële Croteau, Janet K. Thompson, Francis Parchaso, A. Robin Stewart, Kelly H. Shrader, Emily L. Zierdt Smith, Samuel N. LuomaDemethylation of methylmercury in bird, fish, and earthworm
Toxicity of methylmercury (MeHg) to wildlife and humans results from its binding to cysteine residues of proteins, forming MeHg-cysteinate (MeHgCys) complexes that hinder biological functions. MeHgCys complexes can be detoxified in vivo, yet how this occurs is unknown. We report that MeHgCys complexes are transformed into selenocysteinate (Hg(Sec)4) complexes in multiple animals from two phyla (aAuthorsAlain Manceau, Jean-Paul Bourdineaud, Ricardo B. Oliveira, Sandra LF Sarrazin, David P. Krabbenhoft, Collin Eagles-Smith, Josh T. Ackerman, Robin Stewart, Christian Ward-Deitrich, M Estela del Castillo Busto, Heidi Goenaga-Infante, Aude Wack, Marius Retegan, Blanka Detlefs, Pieter Glatzel, Paco Bustamante, Kathryn L. Nagy, Brett PoulinLifetime chronicles of selenium exposure linked to deformities in an imperiled migratory fish
Aquatic ecosystems worldwide face growing threats from elevated levels of contaminants from human activities. Toxic levels of selenium (Se) shown to cause deformities in birds, fish, and mammals can transfer from parents to progeny during embryonic development or accumulate through Se-enriched diets. For migratory species that move across landscapes, tracking exposure to elevated Se is vital to miAuthorsRachel C. Johnson, A. Robin Stewart, Karin Limburg, Rong Huang, Dennis E. Cocherell, Frederick V. FeyrerResolving selenium exposure risk: Spatial, temporal, and tissue-specific variability of an endemic fish in a large, dynamic estuary
Estuaries provide critical habitat for a vast array of fish and wildlife but are also a nexus for core economic activities that mobilize and concentrate contaminants that can threaten aquatic species. Selenium (Se), an essential element and potent reproductive toxin, is enriched in parts of the San Francisco Estuary (SFE) to levels known to cause toxicity, yet the risk of Se to species that inhabiAuthorsA. Robin Stewart, Frederick V. Feyrer, Rachel C. JohnsonNutrients mediate the effects of temperature on methylmercury concentrations in freshwater zooplankton
Methylmercury (MeHg) bioaccumulation in freshwater aquatic systems is impacted by anthropogenic stressors, including climate change and nutrient enrichment. The goal of this study was to determine how warmer water temperatures and excess nutrients would alter zooplankton communities and phytoplankton concentrations, and whether those changes would in turn increase or decrease MeHg concentrations iAuthorsMeredith P Jordan, A. Robin Stewart, Collin A. Eagles-Smith, Angela L StrackerMercury methylation and bioaccumulation in Sinclair Inlet, Kitsap County, Washington
The U.S. Geological Survey evaluated the transformation of mercury to bioavailable methylmercury in Sinclair Inlet, Kitsap County, Washington, and assessed the effect of the transformation processes on the mercury burden in marine organisms and sediment. In August 2008, samples of sediment, water, and biota from six sites in Sinclair Inlet and three bays representative of Puget Sound embayments weAuthorsA.J. Paulson, M.C. Marvin-DiPasquale, P.W. Moran, J.F. DeWild, A.R. Stewart, J. Toft, J.L. Agee, E. Kakouros, Le H. Kieu, B. Carter, R.W. Sheibley, J. Cordell, David P. KrabbenhoftNear-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2017
Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by U.S.AuthorsDaniel J. Cain, Janet K. Thompson, Francis Parchaso, Sarah Pearson, A. Robin Stewart, Matthew A. Turner, David Barasch, Ane Slabic, Samuel N. LuomaNear-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2016
Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by U.S.AuthorsDaniel J. Cain, Janet K. Thompson, Francis Parchaso, Sarah A. Pearson, A. Robin Stewart, Mathew Turner, David Barasch, Samuel N. LuomaA practical method for the determination of total selenium in environmental samples using isotope dilution-hydride generation-inductively coupled plasma-mass spectrometry
A safe, practical, and accurate method for the determination of selenium (Se) in range of environmental samples was developed. Small sample masses, 5–20 mg, were amended with 82Se enriched isotope for the isotope dilution (ID), preceding a multi-step wet digestion with nitric acid (HNO3) and hydrogen peroxide (H2O2). Samples were incubated in an autoclave for 3 h at 20 psi and 126°C. Digestates weAuthorsAmy E. Kleckner, Evangelos Kakouros, A. Robin StewartNon-USGS Publications**
Eagles-Smith CA, Ackerman JT, Willacker JJ, Tate MT, Lutz MA, Fleck JA, Stewart AR, Wiener JG, Evers DC, Lepak JM, Davis JA, Pritz CF (2016) Spatial and temporal patterns of mercury concentrations in freshwater fish across the Western United States and Canada. Sci Total Environ 568:1171-1184
Eagles-Smith CA, Wiener JG, Eckley CS, Willacker JJ, Evers DC, Marvin-DiPasquale M, Obrist D, Fleck JA, Aiken GR, Lepak JM, Jackson AK, Webster JP, Stewart AR, Davis JA, Alpers CN, Ackerman JT (2016) Mercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife. Sci Total Environ 568:1213-1226
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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