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Temporal trends in a biomagnifying contaminant: Application of amino acid compound–specific stable nitrogen isotope analysis to the interpretation of bird mercury levels
Author(s) -
Hebert Craig E.,
Popp Brian N.
Publication year - 2018
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.4092
Subject(s) - trophic level , larus , herring gull , mercury (programming language) , isotope analysis , environmental science , δ15n , isotopes of nitrogen , environmental chemistry , stable isotope ratio , predation , herring , ecology , organism , food chain , pollution , δ13c , chemistry , nitrogen , biology , fishery , paleontology , physics , organic chemistry , quantum mechanics , fish <actinopterygii> , computer science , programming language
Temporal trends in levels of biomagnifying contaminants, such as mercury (Hg), in top predators can provide insights into changes in contaminant bioavailability through time. However, interpreting contaminant temporal trends in predators can be confounded by temporal changes in their diets, which, in turn, could affect organism trophic position and exposure to biomagnifying contaminants. To address this issue, bulk stable nitrogen isotope analysis, that is, analysis of whole tissue, is widely incorporated into contaminant‐monitoring programs for the estimation of organism trophic position. In the present study, we investigated lake‐specific temporal trends in Hg levels in herring gull ( Larus argentatus smithsonianus ) eggs from Lakes Huron and Erie, 2 Laurentian Great Lakes. Levels of Hg in Lake Huron eggs declined, whereas Lake Erie eggs showed no change. Stable nitrogen isotope analysis of bulk material could not explain these interlake differences in Hg temporal trends. However, application of amino acid compound–specific stable nitrogen isotope analysis, in conjunction with other dietary tracers (i.e., fatty acids), provided insights into the factors regulating interlake differences in Hg temporal trends. Adjusting Hg levels in predators to account for temporal changes in their diets can have a significant impact on the interpretation of temporal trend contaminants data. In this case, it reconciled the apparently different Hg temporal trends observed in gull eggs from Lakes Huron and Erie. Environ Toxicol Chem 2018;37:1458–1465. © 2018 SETAC