Limits...
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.

Show MeSH

Related in: MedlinePlus

Relationship between MeHg in worm tissues vs. sediment MeHg.Relationships between continuous variables assessed by linear regression after logarithmic transformations. Points show site means and error bars extend to the minimum and maximum site concentrations.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3928433&req=5

pone-0089305-g004: Relationship between MeHg in worm tissues vs. sediment MeHg.Relationships between continuous variables assessed by linear regression after logarithmic transformations. Points show site means and error bars extend to the minimum and maximum site concentrations.

Mentions: Using multiple regression models to determine the variables best accounting for variation in MeHg concentrations in biota, we found that the concentrations in the different biota were associated with different sediment and water column compartments (Table 1; Table S2 in File S1). Specifically, MeHg concentrations in fish (killifish and silversides) showed significant positive associations with the corresponding water column particulate MeHg concentrations but not with filtered MeHg or sediment MeHg (Table 1; Figure 3). For the full model, sediment and water column variables accounted for 87% of the variation in killifish and, in the reduced model, particulate MeHg alone accounted for 62% of tissue concentration variation. Sediment and water column variables accounted for 92% of the variation in silverside MeHg concentrations, and particulate MeHg concentration alone accounted for 88% in the reduced model. MeHg concentrations of worms were related to sediment MeHg concentrations but not water column concentrations (Figure 4). In the full model, sediment and water column MeHg concentrations accounted for 69% of the tissue variation in worms and when only sediment MeHg was included in a reduced model, it accounted for 55% of the variation (Table 1). Sediment and water column MeHg concentrations were not significantly related to tissue concentrations in mussels or green crabs.


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)

Relationship between MeHg in worm tissues vs. sediment MeHg.Relationships between continuous variables assessed by linear regression after logarithmic transformations. Points show site means and error bars extend to the minimum and maximum site concentrations.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0089305-g004: Relationship between MeHg in worm tissues vs. sediment MeHg.Relationships between continuous variables assessed by linear regression after logarithmic transformations. Points show site means and error bars extend to the minimum and maximum site concentrations.
Mentions: Using multiple regression models to determine the variables best accounting for variation in MeHg concentrations in biota, we found that the concentrations in the different biota were associated with different sediment and water column compartments (Table 1; Table S2 in File S1). Specifically, MeHg concentrations in fish (killifish and silversides) showed significant positive associations with the corresponding water column particulate MeHg concentrations but not with filtered MeHg or sediment MeHg (Table 1; Figure 3). For the full model, sediment and water column variables accounted for 87% of the variation in killifish and, in the reduced model, particulate MeHg alone accounted for 62% of tissue concentration variation. Sediment and water column variables accounted for 92% of the variation in silverside MeHg concentrations, and particulate MeHg concentration alone accounted for 88% in the reduced model. MeHg concentrations of worms were related to sediment MeHg concentrations but not water column concentrations (Figure 4). In the full model, sediment and water column MeHg concentrations accounted for 69% of the tissue variation in worms and when only sediment MeHg was included in a reduced model, it accounted for 55% of the variation (Table 1). Sediment and water column MeHg concentrations were not significantly related to tissue concentrations in mussels or green crabs.

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