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MERCURY BIOACCUMULATION AND TROPHIC TRANSFER IN SYMPATRIC SNAPPER SPECIES FROM THE GULF OF MEXICO
Author(s) -
Bank Michael S.,
Chesney Edward,
Shine James P.,
Maage Amund,
Senn David B.
Publication year - 2007
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/06-1422.1
Subject(s) - trophic level , bioaccumulation , mercury (programming language) , food web , apex predator , ecology , biology , predation , fish measurement , fishery , fish <actinopterygii> , computer science , programming language
Consumption of marine fish is a major route of toxic methyl mercury (MeHg) exposure to ocean apex predators and human populations. Here we explore the influence of trophic structure on total mercury (Hg) accumulation in red snapper (RS, Lutjanus campechanus ) and gray snapper (GS, Lutjanus griseus ) from the coastal Louisiana region of the Gulf of Mexico, west of the Mississippi River. The objectives of this investigation were to: (1) determine the effectiveness of the use of offshore recreational fishing charter boats and marinas as sources of fish samples and (2) compare species differences in Hg bioaccumulation, trophic position, and carbon sources. Our data show that length‐normalized Hg concentrations (≥97% as MeHg in tissue of both species) were 230% greater in GS in comparison to RS collected from the same general area. Stable C and N isotope signatures (δ 15 N and δ 13 C) indicate that GS occupy a slightly higher trophic position (∼30% of one trophic position higher) on the Gulf food web in comparison to RS and that GS appear to incorporate higher trophic positioned prey, continually and at smaller sizes. Mercury was strongly correlated with combined δ 15 N and δ 13 C in pooled species data, arguing that most of the substantial difference in Hg bioaccumulation between RS and GS can be explained by modest differences in their trophic position and, to a lesser degree, carbon sources, which had low variation and high overlap among species. These observations demonstrate that even minor to moderate differences in trophic position and food habits in sympatric species can create relatively large differences in bioaccumulation regimes and underscores the importance of quantitative characterization of trophic structure in marine MeHg bioaccumulation studies.