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Hardy A, Skrabal SA, Addison L, Emslie SD. Biomagnification of mercury in an estuarine food web. MARINE POLLUTION BULLETIN 2024; 205:116604. [PMID: 38936002 DOI: 10.1016/j.marpolbul.2024.116604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 06/12/2024] [Accepted: 06/13/2024] [Indexed: 06/29/2024]
Abstract
Methylmercury is a toxin of local, regional, and global concern, with estuarine habitats possessing ecological characteristics that support conversion of inorganic mercury into this methylated form. We monitored Hg concentrations in species within the food web of the lower Cape Fear River (CFR) estuary in 2018-2020. Samples were analyzed for Hg concentrations and nitrogen isotopes (a measure of trophic level), and we found a positive relationship within this food web each year (p < 0.0001), indicating biomagnification is occurring. The highest Hg concentrations were among the upper trophic level species (Royal Terns, 4.300 ppm). While the Hg concentrations we documented are below assumed thresholds for toxic effects, we found spikes in Hg concentrations after Hurricane Florence in 2018 and with other disturbances to the CFR that resuspended bottom sediments. Continued monitoring is needed to understand the cause of annual variations, health implications, and conservation needs.
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Affiliation(s)
- Anna Hardy
- Department of Biology and Marine Biology, University of North Carolina, Wilmington, NC 28403, USA.
| | - Stephen A Skrabal
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, USA
| | - Lindsay Addison
- Audubon North Carolina, 7741 Market St, Wilmington, NC 28411, USA
| | - Steven D Emslie
- Department of Biology and Marine Biology, University of North Carolina, Wilmington, NC 28403, USA
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2
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Bonisoli-Alquati A, Jackson AK, Eagles-Smith CA, Moyo S, Pérez-Umphrey AA, Polito MJ, Snider AM, Williams ST, Woltmann S, Stouffer PC, Taylor SS. Mercury concentrations in Seaside Sparrows and Marsh Rice Rats differ across the Mississippi River Estuary. ECOTOXICOLOGY (LONDON, ENGLAND) 2024:10.1007/s10646-024-02789-1. [PMID: 39048895 DOI: 10.1007/s10646-024-02789-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/08/2024] [Indexed: 07/27/2024]
Abstract
Mercury (Hg) concentrations and their associated toxicological effects in terrestrial ecosystems of the Gulf of Mexico are largely unknown. Compounding this uncertainty, a large input of organic matter from the 2010 Deepwater Horizon oil spill may have altered Hg cycling and bioaccumulation dynamics. To test this idea, we quantified blood concentrations of total mercury (THg) in Seaside Sparrows (Ammospiza maritima) and Marsh Rice Rats (Oryzomys palustris) in marshes west and east of the Mississippi River in 2015 and 2016. We also tested for a difference in THg concentrations between oiled and non-oiled sites. To address the potential confounding effect of diet variation on Hg transfer, we used stable nitrogen (δ15N) and carbon (δ13C) isotope values as proxies of trophic position and the source of primary production, respectively. Our results revealed that five to six years after the spill, THg concentrations were not higher in sites oiled by the spill compared to non-oiled sites. In both species, THg was higher at sites east of the Mississippi River compared to control and oiled sites, located west. In Seaside Sparrows but not in Marsh Rice Rats, THg increased with δ15N values, suggesting Hg trophic biomagnification. Overall, even in sites with the most elevated THg, concentrations were generally low. In Seaside Sparrows, THg concentrations were also lower than previously reported in this and other closely related passerines, with only 7% of tested birds exceeding the lowest observed effect concentration associated with toxic effects across bird species (0.2 µg/g ww). The factors associated with geographic heterogeneity in Hg exposure remain uncertain. Clarification could inform risk assessment and future restoration and management actions in a region facing vast anthropogenic changes.
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Affiliation(s)
- Andrea Bonisoli-Alquati
- Department of Biological Sciences, California State Polytechnic University, Pomona, Pomona, CA, 91768, USA.
| | - Allyson K Jackson
- Purchase College SUNY, Department of Environmental Studies, Purchase, NY, 10577, USA
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Sydney Moyo
- Louisiana State University, Department of Biological Sciences, Baton Rouge, LA, 70803, USA
| | - Anna A Pérez-Umphrey
- School of Renewable Natural Resources, Louisiana State University and LSU AgCenter, Baton Rouge, LA, 70803, USA
| | - Michael J Polito
- Louisiana State University, Department of Oceanography and Coastal Sciences, Baton Rouge, LA, 70803, USA
| | - Allison M Snider
- School of Renewable Natural Resources, Louisiana State University and LSU AgCenter, Baton Rouge, LA, 70803, USA
| | - S Tyler Williams
- School of Renewable Natural Resources, Louisiana State University and LSU AgCenter, Baton Rouge, LA, 70803, USA
| | - Stefan Woltmann
- Center of Excellence for Field Biology, and Department of Biology, Austin Peay State University, Clarksville, TN, 37040, USA
| | - Philip C Stouffer
- School of Renewable Natural Resources, Louisiana State University and LSU AgCenter, Baton Rouge, LA, 70803, USA
| | - Sabrina S Taylor
- School of Renewable Natural Resources, Louisiana State University and LSU AgCenter, Baton Rouge, LA, 70803, USA
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3
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Ruskin KJ, Herring G, Eagles-Smith CA, Eiklor AB, Elphick CS, Etterson MA, Field CR, Longenecker RA, Kovach AI, Gregory Shriver W, Walsh J, Olsen BJ. Mercury exposure of tidal marsh songbirds in the northeastern United States and its association with nest survival. ECOTOXICOLOGY (LONDON, ENGLAND) 2022; 31:208-220. [PMID: 34783931 DOI: 10.1007/s10646-021-02488-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/25/2021] [Indexed: 06/13/2023]
Abstract
The biogeochemistry of tidal marsh sediments facilitates the transformation of mercury (Hg) into the biologically available form methylmercury (MeHg), resulting in elevated Hg exposures to tidal marsh wildlife. Saltmarsh and Acadian Nelson's sparrows (Ammospiza caudacutua and A. nelsoni subvirgatus, respectively) exclusively inhabit tidal marshes, potentially experiencing elevated risk to Hg exposure, and have experienced range-wide population declines. To characterize spatial and temporal variation of Hg exposure in these species, we sampled total mercury (THg) in blood collected from 9 populations spanning 560 km of coastline, including individuals resampled within and among years. Using concurrent nesting studies, we tested whether THg was correlated with nest survival probabilities, an index of fecundity. Blood THg ranged from 0.074-3.373 µg/g ww across 170 samples from 127 individuals. We detected high spatial variability in Hg exposure, observing differences of more than 45-fold across all individuals and 8-fold in mean blood THg among all study plots, including 4-fold between study plots within 4 km. Intraindividual changes in blood Hg exposure did not vary systematically in time but were considerable, varying by up to 2-fold within and among years. Controlling for both species differences and maximum water level, the dominant driver of fecundity in this system, nest survival probability decreased by 10% across the full range of female blood THg concentrations observed. We conclude that Hg has the potential to impair songbird reproduction, potentially exacerbating known climate-change driven population declines from sea-level rise in saltmarsh and Acadian Nelson's sparrows.
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Affiliation(s)
- Katharine J Ruskin
- Ecology and Environmental Sciences, 123 Bryand Global Sciences Center, University of Maine, Orono, ME, 04469, USA.
| | - Garth Herring
- United States Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Collin A Eagles-Smith
- United States Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR, 97331, USA
| | - Alyssa B Eiklor
- Vermont Department of Environmental Conservation, 1 National Life Dr Montpelier, Davis 1, VT, 05620-3520, USA
| | - Chris S Elphick
- Department of Ecology & Evolutionary Biology and Center of Biological Risk, University of Connecticut, 75 North Eagleville Road, U-43, Storrs, CT, 06269, USA
| | - Matthew A Etterson
- United States Environmental Protection Agency, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, 6201 Congdon Boulevard, Duluth, MN, 55804, USA
| | - Christopher R Field
- Department of Natural Resources Science, University of Rhode Island 45 Upper College Rd, Kingston, RI, 02881, USA
| | - Rebecca A Longenecker
- U.S. Fish and Wildlife Service, Northeast Regional Office, 300 Westgate Center Drive, Hadley, MA, 01035, USA
| | - Adrienne I Kovach
- Department of Natural Resources and the Environment, University of New Hampshire, 46 College Road, Durham, NH, 03824, USA
| | - W Gregory Shriver
- Department of Entomology and Wildlife Ecology, University of Delaware, 257 Townsend Hall, Newark, DE, 19716, USA
| | - Jennifer Walsh
- Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, NY, 14850, USA
| | - Brian J Olsen
- Ecology and Environmental Sciences, 123 Bryand Global Sciences Center, University of Maine, Orono, ME, 04469, USA
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Génier CSV, Guglielmo CG, Mitchell GW, Falconer M, Hobson KA. Nutritional consequences of breeding away from riparian habitats in Bank Swallows: new evidence from multiple endogenous markers. CONSERVATION PHYSIOLOGY 2021; 9:coaa140. [PMID: 33532072 PMCID: PMC7836397 DOI: 10.1093/conphys/coaa140] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/07/2020] [Accepted: 12/28/2020] [Indexed: 06/01/2023]
Abstract
The Bank Swallow (Riparia riparia), a threatened species in Canada, breeds primarily in banks at lakeshores and rivers and in artificial (typically inland) aggregate mining pits. Inland pits may be ecological traps for this species, but relative dietary trade-offs between these two nesting habitats have not been investigated. The availability of aquatic emergent insects at lakeshores may have associated nutritional benefits for growing nestlings due to increased omega-3 fatty acids (FAs) in prey. We compared the diets of juvenile swallows from lakeshore and inland pit sites using assays of stable isotope values (δ13C, δ15N, δ2H) of feathers, faecal DNA metabarcoding and blood plasma FAs. Colony proximity to Lake Erie influenced the use of aquatic versus terrestrial insects by Bank Swallow adults and juveniles. Feather δ2H was particularly useful as a tracer of aquatic emergent versus terrestrial prey, and inland juveniles had feathers enriched in 2H, reflective of diets composed of fewer aquatic emergent insects. DNA metabarcoding of juvenile and adult faecal material indicated that lakeshore birds consumed more aquatic-emergent chironomids than inland birds. Lakeshore juveniles had elevated plasma omega-3 eicosapentaenoic acid levels compared with inland pit-breeding birds. We discuss the need to consider 'nutritional landscapes' and the importance of this concept in conservation of declining species and populations.
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Affiliation(s)
- Corrine S V Génier
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Christopher G Guglielmo
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
| | - Greg W Mitchell
- Environment and Climate Change Canada, Wildlife Research Division, 1125 Colonel By Drive, Ottawa, Ontario K1A 0H3, Canada
| | - Myles Falconer
- Birds Canada, 115 Front Rd., P.O. Box 160, Port Rowan, Ontario N0E 1M0, Canada
| | - Keith A Hobson
- Department of Biology, University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada
- Environment and Climate Change Canada, Wildlife Research Division, 11 Innovation Blvd., Saskatoon, Saskatchewan S7N 3H5, Canada
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Brasso R, Rittenhouse KA, Winder VL. Do songbirds in wetlands show higher mercury bioaccumulation relative to conspecifics in non-wetland habitats? ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1183-1194. [PMID: 31942663 DOI: 10.1007/s10646-020-02160-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
Environmental conditions in wetlands facilitate favorable biogeochemical conditions for the conversion of inorganic mercury into methylmercury. For this reason, wetlands are increasingly classified as mercury hotspots, places where biota exhibit elevated mercury concentrations. While it is clear that wetlands play an important role in methylmercury production, factors such as geographic variation in mercury deposition, wetland type, and trophic dynamics can cause variation in mercury dynamics and bioaccumulation in biota occupying wetlands or connected to wetland trophic systems. Here, we use songbirds as bioindicators in a two-pronged approach aimed at evaluating the state of our understanding of mercury bioaccumulation by songbirds in wetland ecosystems. First, we use a case study in southeast Missouri to compare blood mercury concentrations in tree swallows (Tachycineta bicolor) and eastern bluebirds (Sialia sialis) occupying wetland and non-wetland habitats to test the hypothesis that songbirds in wetlands will have higher mercury bioaccumulation than those in non-wetlands. Adult tree swallows in wetlands had significantly higher blood mercury concentrations than those in non-wetlands; however, no difference between ecosystems was detected in eastern bluebirds. Second, we present a review of the current literature on mercury in songbirds in wetland ecosystems across North America. Mercury concentrations in songbirds varied among wetland types and with geographic location, often in an unpredictable manner. Mercury concentrations in songbird blood varied 3-10 fold at locations separated only by ~10 to several hundred kilometers. This magnitude of difference in blood mercury concentrations among wetlands exceeds documented differences between wetland and non-wetland ecosystems. Therefore, we caution against the automatic assumption that songbirds occupying wetlands will have higher mercury bioaccumulation than conspecifics living in other habitats.
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Affiliation(s)
- Rebecka Brasso
- Department of Zoology, Weber State University, Ogden, UT, 84408, USA.
| | - Katie Ann Rittenhouse
- Department of Biology, Southeast Missouri State University, Cape Girardeau, MO, 63701, USA
| | - Virginia L Winder
- Department of Biology, Benedictine College, Atchison, KS, 66002, USA
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6
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Lane O, Adams EM, Pau N, O'Brien KM, Regan K, Farina M, Schneider-Moran T, Zarudsky J. Long-term monitoring of mercury in adult saltmarsh sparrows breeding in Maine, Massachusetts and New York, USA 2000-2017. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1148-1160. [PMID: 32124146 DOI: 10.1007/s10646-020-02180-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/17/2020] [Indexed: 06/10/2023]
Abstract
Here we report on the results of a long-term study of mercury exposure in a songbird species, the saltmarsh sparrow (Ammodramus caudacutus). We measured total mercury concentrations in blood (n = 840) and feathers (n = 560) of adult saltmarsh sparrows at six locations between 2000 and 2017: Rachel Carson National Wildlife Refuge (RCNWR) in Wells, Maine; Scarborough Marsh State Wildlife Management Area in Scarborough, Maine; Parker River National Wildlife Refuge on Plum Island, Massachusetts; Pine Neck Preserve in Southampton, Long Island, New York; and North Cinder and North Green Sedge Islands off the coast of Long Island, New York. During the 12-17 year sampling periods, we found that mercury exposure differed by site and year but there was no consistent temporal trend across sites. Blood mercury concentrations declined only at RCNWR in Maine. We also found seasonal variation in blood mercury concentrations and a positive relationship between mercury concentrations of blood and innermost primary feather, but not between blood and tail feather.
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Affiliation(s)
- Oksana Lane
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA.
| | - Evan M Adams
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Nancy Pau
- USFWS, Parker River NWR, 6 Plum Island Turnpike, Newburyport, MA, 01950, USA
| | | | - Kevin Regan
- Biodiversity Research Institute, 276 Canco Road, Portland, ME, 04103, USA
| | - Michael Farina
- Town of Hempstead: Department of Conservation and Waterways, 1401 Lido Blvd, Point Lookout, NY, 11561, USA
| | - Tara Schneider-Moran
- Town of Hempstead: Department of Conservation and Waterways, 1401 Lido Blvd, Point Lookout, NY, 11561, USA
| | - John Zarudsky
- Town of Hempstead: Department of Conservation and Waterways, 1401 Lido Blvd, Point Lookout, NY, 11561, USA
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Winder VL, Anteau MJ, Fisher MR, Wilcox MK, Igl LD, Ackerman JT. Wetland water-management may influence mercury bioaccumulation in songbirds and ducks at a mercury hotspot. ECOTOXICOLOGY (LONDON, ENGLAND) 2020; 29:1229-1239. [PMID: 31902053 DOI: 10.1007/s10646-019-02143-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Mercury is a persistent, biomagnifying contaminant that can cause negative behavioral, immunological, and reproductive effects in wildlife and human populations. We examined the role of wetland water-management on mercury bioaccumulation in songbirds and ducks at Kellys Slough National Wildlife Refuge Complex, near Grand Forks, North Dakota USA. We assessed mercury concentrations in blood of wetland-foraging songbirds (80 common yellowthroats [Geothlypis trichas] and 14 Nelson's sparrows [Ammospiza nelsoni]) and eggs of upland-nesting ducks (28 gadwall [Mareca strepera], 19 blue-winged teal [Spatula discors], and 13 northern shoveler [S. clypeta]) across four wetland water-management classifications. Nelson's sparrow blood mercury concentrations were elevated (mean: 1.00 µg/g ww; 95% CL: 0.76-1.31) and similar to those reported 6 years previously. Mercury in songbird blood and duck eggs varied among wetland water-management classifications. Songbirds and ducks had 67% and 49% lower mercury concentrations, respectively, when occupying wetlands that were drawn down with water flow compared to individuals occupying isolated-depressional wetlands with no outflow. Additionally, songbirds within impounded and partially drawn-down wetland units with water flow had mercury concentrations that were 26-28% lower, respectively, than individuals within isolated-depressional wetlands with no outflow. Our results confirm that mercury concentrations in songbirds at Kellys Slough continue to be elevated and suggest that water-management could be an important tool for wetland managers to reduce bioaccumulation of mercury in birds.
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Affiliation(s)
- Virginia L Winder
- Department of Biology, Benedictine College, Atchison, KS, 66002, USA.
| | - Michael J Anteau
- Northern Prairie Wildlife Research Center, U.S. Geological Survey, 8711 37th St SE, Jamestown, ND, 58401, USA
| | - Mark R Fisher
- Devils Lake Wetland Management District, U.S. Fish and Wildlife Service, Devils Lake, ND, 58301, USA
| | - Mary Kate Wilcox
- Division of Biology, Kansas State University, Manhattan, KS, 66502, USA
| | - Lawrence D Igl
- Northern Prairie Wildlife Research Center, U.S. Geological Survey, 8711 37th St SE, Jamestown, ND, 58401, USA
| | - Joshua T Ackerman
- Western Ecological Research Center, Dixon Field Station, U.S. Geological Survey, 800 Business Park Drive, Suite D, Dixon, CA, 95620, USA
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Kopec AD, Bodaly RA, Lane OP, Evers DC, Leppold AJ, Mittelhauser GH. Elevated mercury in blood and feathers of breeding marsh birds along the contaminated lower Penobscot River, Maine, USA. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:1563-1579. [PMID: 29710654 DOI: 10.1016/j.scitotenv.2018.03.223] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 03/06/2018] [Accepted: 03/19/2018] [Indexed: 06/08/2023]
Abstract
Mercury (Hg) concentrations in the blood and feathers of five species of migratory marsh birds, Nelson's sparrow (Ammodramus nelson subvirgatus), song sparrow (Melospiiza melodia), swamp sparrow (Melospiza geogiana), red-winged blackbird (Agelaius phoeniceus), and Virginia rail (Rallus limicola), breeding in marshes along the lower Penobscot River, Maine, far exceeded reference concentrations, exceeded concentrations associated with reproductive health, and are the highest Hg concentrations reported to date for several species. Blood Hg concentrations in adult Nelson's sparrows were greatest in 2007, at 6.6μg/gww (geometric mean) and in 2012, at 6.5μg/gww and greatest in red-winged blackbirds in 2012, 8.0μg/gww. Mercury in blood increased with residence time on the contaminated marshes at an estimated rate of 0.04 to 0.07μg/gww per day. Feather mercury concentrations in specific primary, secondary and tail feathers (P1, S2, R6) were strongly associated with exposure location at the time of feather formation. Geometric mean Hg concentrations in primary feathers (P1) reached 39.6μg/gfw in 2010 in Nelson's sparrows. The paper documents the dynamic nature of Hg concentrations in avian blood and feathers, an important consideration in contaminant study design, and the increased risk to marsh birds posed by Hg deposition from upstream sources.
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Affiliation(s)
- A Dianne Kopec
- Penobscot River Mercury Study, 479 Beechwood Ave. Old Town, ME 04468, USA.
| | - R A Bodaly
- Penobscot River Mercury Study, 115 Oystercatcher Place, Salt Spring Island, British Columbia V8K 2W5, Canada
| | - Oksana P Lane
- Biodiversity Research Institute, 276 Canco Rd., Portland, ME 04103, USA
| | - David C Evers
- Biodiversity Research Institute, 276 Canco Rd., Portland, ME 04103, USA
| | - Adrienne J Leppold
- Maine Natural History Observatory, 317 Guzzle Rd., Gouldsboro, ME 04607, USA; Maine Department of Inland Fisheries and Wildlife, 650 State Street, Bangor, ME 04401, USA
| | - Glen H Mittelhauser
- Maine Natural History Observatory, 317 Guzzle Rd., Gouldsboro, ME 04607, USA
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Silverthorn VM, Bishop CA, Jardine T, Elliott JE, Morrissey CA. Impact of flow diversion by run-of-river dams on American dipper diet and mercury exposure. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2018; 37:411-426. [PMID: 29092091 DOI: 10.1002/etc.3961] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/13/2017] [Accepted: 08/22/2017] [Indexed: 06/07/2023]
Abstract
Run-of-river dams produce lower greenhouse gas emissions than large hydropower projects, but there is a paucity of research on their potential ecotoxicological impacts through disruption of natural flow regimes. We used stable isotopes (δ13 C, δ15 N, δ34 S) to reconstruct diet and trace methylmercury in a predatory river-resident passerine, the American dipper (Cinclus mexicanus), at 7 regulated and 6 free-flowing mountain streams in coastal British Columbia, Canada. Assimilated diets were comparable among regulated and unregulated streams, dominated by benthic macroinvertebrates and resident freshwater fish, with negligible contributions from anadromous Pacific salmon. Although invertebrates at unregulated streams were isotopically similar along their gradient, dippers and invertebrates sampled below dams on regulated streams had 34 S-depleted tissues, suggesting increased activity of sulfate-reducing bacteria and more Hg methylation below the dams. Mercury concentrations in dipper blood (417.6 ± 74.1 standard error [SE] ng/g wet wt at regulated streams, 340.7 ± 42.7 SE ng/g wet wt at unregulated streams) and feathers (1564 .6 ± 367.2 SE ng/g dry wt regulated, 1149.0 ± 152.1 SE ng/g dry wt unregulated), however, were not significantly different between stream types. Relative to other passerines across western North America, dippers in these densely forested mountain streams experienced high mercury exposure; and one recently regulated stream supported dippers with mercury concentrations of potential toxicity concern (up to 8459.5 ng/g dry wt in feathers and 1824.6 ng/g wet wt in whole blood). Elevated mercury in dippers is likely attributable to the birds' relatively high trophic position and high regional inorganic mercury deposition; however, biogeochemical conditions in reservoirs of some regulated streams may be contributing to methylmercury production. Environ Toxicol Chem 2018;37:411-426. © 2017 SETAC.
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Affiliation(s)
| | - Christine A Bishop
- Environment and Climate Change Canada, Wildlife and Landscape Science Division, Delta, British Columbia, Canada
| | - Timothy Jardine
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - John E Elliott
- Environment and Climate Change Canada, Wildlife and Landscape Science Division, Delta, British Columbia, Canada
| | - Christy A Morrissey
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Fournier AMV, Welsh KJ, Polito M, Emslie SD, Brasso R. Levels of Mercury in Feathers of Clapper Rails (Rallus crepitans) over 45 Years in Coastal Salt Marshes of New Hanover County, North Carolina. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 97:469-473. [PMID: 27370821 DOI: 10.1007/s00128-016-1870-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 06/23/2016] [Indexed: 06/06/2023]
Abstract
We sampled clapper rail (Rallus crepitans) feathers from museum specimens collected between 1965 and 2010 to investigate changes in mercury (Hg) availability in coastal marshes of New Hanover County, North Carolina. Stable isotope analysis (δ(13)C and δ(15)N) was conducted to control for dietary shifts that may have influenced Hg exposure. Hg concentrations ranged from 0.96 to 9.22 μg/g (ppm), but showed no significant trend over time; diet (δ(15)N) or foraging habitat (δ(13)C) also provided little to no explanatory power to the variation in Hg concentrations among clapper rails. Our findings suggest the bioavailability of Hg to clapper rails in coastal North Carolina salt marshes has remained consistent over time, despite the global trend of increasing mercury in many other bird species, providing an excellent baseline for any future assessment of Hg availability to salt marsh birds in coastal North Carolina.
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Affiliation(s)
- Auriel M V Fournier
- Arkansas Cooperative Fish and Wildlife Research Unit, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Kyle James Welsh
- Department of Biological Sciences, University of Alberta, 116 Street and 85 Avenue, Edmonton, AB, T6G 2R3, Canada
| | - Michael Polito
- Department of Oceanography and Coastal Sciences, Louisiana State University, 1239 Energy, Coast and Environment Building, Baton Rouge, LA, 70803, USA
| | - Steven D Emslie
- Department of Biology and Marine Biology, University of North Carolina, 601 South College Road, Wilmington, NC, 28403, USA
| | - Rebecka Brasso
- Department of Biology, Southeast Missouri State University, One University Plaza, MS 6200, Cape Girardeau, MO, 63701, USA
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11
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Varian-Ramos CW, Swaddle JP, Cristol DA. Mercury reduces avian reproductive success and imposes selection: an experimental study with adult- or lifetime-exposure in zebra finch. PLoS One 2014; 9:e95674. [PMID: 24759822 PMCID: PMC3997408 DOI: 10.1371/journal.pone.0095674] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 03/31/2014] [Indexed: 02/06/2023] Open
Abstract
Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 – 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success.
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Affiliation(s)
- Claire W. Varian-Ramos
- Biology Department, Colorado State University – Pueblo, Pueblo, Colorado, United States of America
- * E-mail:
| | - John P. Swaddle
- Institute for Integrative Bird Behavior Studies, Biology Department, The College of William and Mary, Williamsburg, Virginia, United States of America
| | - Daniel A. Cristol
- Institute for Integrative Bird Behavior Studies, Biology Department, The College of William and Mary, Williamsburg, Virginia, United States of America
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Winder VL. Characterization of mercury and its risk in Nelson's, Saltmarsh, and Seaside Sparrows. PLoS One 2012; 7:e44446. [PMID: 22962614 PMCID: PMC3433451 DOI: 10.1371/journal.pone.0044446] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 08/07/2012] [Indexed: 11/18/2022] Open
Abstract
Background Nelson’s, Saltmarsh, and Seaside Sparrows (Ammodramus nelsoni, A. caudacutus, and A. maritimus, respectively) depend on marsh and wetland habitats – ecosystems in which mercury (Hg) bioavailability is notoriously high. The purpose of the present study was to address the potential impact of Hg on these species using first primary and breast feathers as non-destructive biomonitoring tools. Methods and Principal Findings Feathers were sampled from wintering sparrows in North Carolina salt marshes (2006–2010). Feather Hg data were used in three risk analysis components (1) Threshold Component – examined feather Hg with regard to published negative effects thresholds; (2) Hg Dynamics Component – examined Hg in sparrows captured multiple times; and (3) Capture Frequency and Survival Component – tested for links between Hg and return frequency and survival. Threshold Component analyses indicated that Hg concentrations in 42–77% of sampled individuals (breast feather n = 879; first primary feather n = 663) were within the range associated with decreased reproduction in other avian species. Hg Dynamics Component analyses demonstrated that Hg increased between first and second captures for Nelson’s (n = 9) and Seaside Sparrows (n = 23). Capture Frequency and Survival Component analyses detected a negative relationship between Hg and capture frequency in Nelson’s Sparrows (n = 315). However, MARK models detected no effect of Hg on apparent survival in any species. Conclusion and Significance This study indicates that current Hg exposure places a considerable proportion of each population at risk. In particular, 52% of all sampled Saltmarsh Sparrows exhibited first primary feather Hg concentrations exceeding those associated with a >60% reduction in reproductive success in other species. This study reports evidence for net annual bioaccumulation, indicating an increased risk in older individuals. These data can be used to inform future population assessments and management for these species.
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Affiliation(s)
- Virginia L Winder
- Department of Biology and Marine Biology, University of North Carolina at Wilmington, Wilmington, North Carolina, United States of America.
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Winder VL, Emslie SD. Mercury in Nelson's Sparrow subspecies at breeding sites. PLoS One 2012; 7:e32257. [PMID: 22384194 PMCID: PMC3285213 DOI: 10.1371/journal.pone.0032257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/24/2012] [Indexed: 11/23/2022] Open
Abstract
Background Mercury is a persistent, biomagnifying contaminant that can cause negative effects on ecosystems. Marshes are often areas of relatively high mercury methylation and bioaccumulation. Nelson's Sparrows (Ammodramus nelsoni) use marsh habitats year-round and have been documented to exhibit tissue mercury concentrations that exceed negative effects thresholds. We sought to further characterize the potential risk of Nelson's Sparrows to mercury exposure by sampling individuals from sites within the range of each of its subspecies. Methodology/Principal Findings From 2009 to 2011, we captured adult Nelson's Sparrows at sites within the breeding range of each subspecies (A. n. nelsoni: Grand Forks and Upham, North Dakota; A. n. alterus: Moosonee, Ontario; and A. n. subvirgatus: Grand Manan Island, New Brunswick) and sampled breast feathers, the first primary feather (P1), and blood for total mercury analysis. Mean blood mercury in nelsoni individuals captured near Grand Forks ranged from 0.84±0.37 to 1.65±1.02 SD ppm among years, between 2.0 and 4.9 times as high as concentrations at the other sites (P<0.01). Breast feather mercury did not vary among sites within a given sampling year (site means ranged from 0.98±0.69 to 2.71±2.93 ppm). Mean P1 mercury in alterus (2.96±1.84 ppm fw) was significantly lower than in any other sampled population (5.25±2.24–6.77±3.51 ppm; P≤0.03). Conclusions/Significance Our study further characterized mercury in Nelson's Sparrows near Grand Forks; we documented localized and potentially harmful mercury concentrations, indicating that this area may represent a biological mercury hotspot. This finding warrants further research to determine if wildlife populations of conservation or recreational interest in this area may be experiencing negative effects due to mercury exposure. We present preliminary conclusions about the risk of each sampled population to mercury exposure.
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Affiliation(s)
- Virginia L Winder
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, United States of America.
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