title: Mercury bioaccumulation in cartilaginous fishes from Southern New England coastal waters: contamination from a trophic ecology and human health perspective.
abstract: This study examined total mercury (Hg) concentrations in cartilaginous fishes from Southern New England coastal waters, including smooth dogfish (Mustelus canis), spiny dogfish (Squalus acanthias), little skate (Leucoraja erinacea), and winter skate (Leucoraja ocellata). Total Hg in dogfish and skates were positively related to their respective body size and age, indicating Hg bioaccumulation in muscle tissue. There were also significant inter-species differences in Hg levels (mean ± 1 SD, mg Hg/kg dry weight, ppm): smooth dogfish (3.3 ± 2.1 ppm; n = 54) > spiny dogfish (1.1 ± 0.7 ppm; n = 124) > little skate (0.4 ± 0.3 ppm; n = 173) ∼ winter skate (0.3 ± 0.2 ppm; n = 148). The increased Hg content of smooth dogfish was attributed to its upper trophic level status, determined by stable nitrogen (δ(15)N) isotope analysis (mean δ(15)N = 13.2 ± 0.7‰), and the consumption of high Hg prey, most notably cancer crabs (0.10 ppm). Spiny dogfish had depleted δ(15)N signatures (11.6 ± 0.8‰), yet demonstrated a moderate level of contamination by foraging on pelagic prey with a range of Hg concentrations, e.g., in order of dietary importance, butterfish (Hg = 0.06 ppm), longfin squid (0.17 ppm), and scup (0.11 ppm). Skates were low trophic level consumers (δ(15)N = 11.9-12.0‰) and fed mainly on amphipods, small decapods, and polychaetes with low Hg concentrations (0.05-0.09 ppm). Intra-specific Hg concentrations were directly related to δ(15)N and carbon (δ(13)C) isotope signatures, suggesting that Hg biomagnifies across successive trophic levels and foraging in the benthic trophic pathway increases Hg exposure. From a human health perspective, 87% of smooth dogfish, 32% of spiny dogfish, and <2% of skates had Hg concentrations exceeding the US Environmental Protection Agency threshold level (0.3 ppm wet weight). These results indicate that frequent consumption of smooth dogfish and spiny dogfish may adversely affect human health, whereas skates present minimal risk.
authors.affiliation: Roger Williams University, Department of Marine Biology, One Old Ferry Road, Bristol, RI 02809, USA. Electronic address: dtaylor@rwu.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Taylor
authors.affiliation: Roger Williams University, Department of Marine Biology, One Old Ferry Road, Bristol, RI 02809, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Kutil
authors.affiliation: University of Rhode Island, Graduate School of Oceanography, South Ferry Road, Narragansett, RI 02882, USA.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Malek
authors.affiliation: University of Rhode Island, Graduate School of Oceanography, South Ferry Road, Narragansett, RI 02882, USA.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Collie
mesh_terms: D000818:Animals; D001267:Atlantic Ocean; D004284:Dogfish / Q000378:metabolism*; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D020387:Food Chain; D005506:Food Contamination / Q000032:analysis*; D008628:Mercury / Q000032:analysis / Q000493:pharmacokinetics*; D009511:New England; D009587:Nitrogen Isotopes / Q000032:analysis; D012860:Skates, Fish / Q000378:metabolism*; D013045:Species Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000493:pharmacokinetics*
chemical_list: D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Bioaccumulation; Diet; Dogfish; Food web; Mercury; Skate; Stable isotope
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