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Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.

Chen CY, Borsuk ME, Bugge DM, Hollweg T, Balcom PH, Ward DM, Williams J, Mason RP - PLoS ONE (2014)

Bottom Line: MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides).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.

View Article: PubMed Central - PubMed

Affiliation: Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire, United States of America.

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.

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Stable isotope signatures of individual taxonomic groups measured as delta 13C and delta 15N.Delta 15N values were adjusted for site differences. Because of significantly different patterns, worms were excluded from analysis. Crosshairs show +/− two standard errors.
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pone-0089305-g005: Stable isotope signatures of individual taxonomic groups measured as delta 13C and delta 15N.Delta 15N values were adjusted for site differences. Because of significantly different patterns, worms were excluded from analysis. Crosshairs show +/− two standard errors.

Mentions: Measurements of stable isotopes as indicators of trophic level (δ15N) and carbon source of food (δ13C) were used to determine trophic and feeding relationships between fauna and their relationship to biotic MeHg concentrations. When adjusted for site, relative δ15N values indicate that the two fish species represented the highest trophic levels followed by green crabs, worms, and then mussels (Figure 5; Table S2 in File S1). Mussels and silversides were the most depleted in δ13C indicating their pelagic food sources whereas killifish consume food sources more intermediate between pelagic and benthic, and worms and green crabs had the least depleted δ13C indicating the most benthic food sources (Figure 5; Table S2 in File S1). Although two sites had blue mussels rather than ribbed mussels, the δ13C of the two species of mussels were not distinctly different and blue mussel values fell within the range of ribbed mussels.


Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.

Chen CY, Borsuk ME, Bugge DM, Hollweg T, Balcom PH, Ward DM, Williams J, Mason RP - PLoS ONE (2014)

Stable isotope signatures of individual taxonomic groups measured as delta 13C and delta 15N.Delta 15N values were adjusted for site differences. Because of significantly different patterns, worms were excluded from analysis. Crosshairs show +/− two standard errors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928433&req=5

pone-0089305-g005: Stable isotope signatures of individual taxonomic groups measured as delta 13C and delta 15N.Delta 15N values were adjusted for site differences. Because of significantly different patterns, worms were excluded from analysis. Crosshairs show +/− two standard errors.
Mentions: Measurements of stable isotopes as indicators of trophic level (δ15N) and carbon source of food (δ13C) were used to determine trophic and feeding relationships between fauna and their relationship to biotic MeHg concentrations. When adjusted for site, relative δ15N values indicate that the two fish species represented the highest trophic levels followed by green crabs, worms, and then mussels (Figure 5; Table S2 in File S1). Mussels and silversides were the most depleted in δ13C indicating their pelagic food sources whereas killifish consume food sources more intermediate between pelagic and benthic, and worms and green crabs had the least depleted δ13C indicating the most benthic food sources (Figure 5; Table S2 in File S1). Although two sites had blue mussels rather than ribbed mussels, the δ13C of the two species of mussels were not distinctly different and blue mussel values fell within the range of ribbed mussels.

Bottom Line: MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides).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.

View Article: PubMed Central - PubMed

Affiliation: Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire, United States of America.

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.

Show MeSH
Related in: MedlinePlus