title: Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.
abstract: Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides). Moreover, MeHg concentrations were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concentrations were only predictive of concentrations of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that determine MeHg input and bioavailability in the water column.
authors.affiliation: Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire, United States of America.
authors.forename: Celia Y
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Dartmouth College, Thayer School of Engineering, Hanover, New Hampshire, United States of America.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Borsuk
authors.affiliation: Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire, United States of America.
authors.forename: Deenie M
authors.initials: DM
authors.lastname: Bugge
authors.affiliation: Stratus Consulting, Boulder, Colorado, United States of America.
authors.forename: Terill
authors.initials: T
authors.lastname: Hollweg
authors.affiliation: University of Connecticut, Department of Marine Science, Groton, Connecticut, United States of America.
authors.forename: Prentiss H
authors.initials: PH
authors.lastname: Balcom
authors.affiliation: Humboldt State University, Department of Fisheries Biology, Arcata, California, United States of America.
authors.forename: Darren M
authors.initials: DM
authors.lastname: Ward
authors.affiliation: Washington State University, Department of Civil and Environmental Engineering, Pullman, Washington, United States of America.
authors.forename: Jason
authors.initials: J
authors.lastname: Williams
authors.affiliation: University of Connecticut, Department of Marine Science, Groton, Connecticut, United States of America.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Mason
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D004785:Environmental Pollutants / Q000493:pharmacokinetics*; D063366:Estuaries / Q000706:statistics & numerical data*; D020387:Food Chain; D023781:Fundulidae / Q000378:metabolism*; D019015:Geologic Sediments / Q000032:analysis; D006801:Humans; D016014:Linear Models; D013058:Mass Spectrometry; D008767:Methylmercury Compounds / Q000493:pharmacokinetics*; D009511:New England; D009587:Nitrogen Isotopes / Q000032:analysis; D012623:Seawater / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D009587:Nitrogen Isotopes