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Application of stable isotope mixing models for defining trophic biomagnification pathways of mercury and selenium

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posted on 2023-05-18, 01:33 authored by Jones, HJ, Kerrie SwadlingKerrie Swadling, Butler, ECV, Barry, LA, Catriona MacLeodCatriona MacLeod
Trophic models based on nitrogen stable isotope ratios (δ15N) have been shown to predict changes in mercury (Hg) concentrations in fish; however, they are usually applied at the ecosystem scale and are rarely directed at known trophic pathways. We discuss a novel approach in which we combined gut contents analysis and stable isotope analyses (δ15N and δ13C) into a Bayesian isotopic mixing model to provide a quantitative estimate of Hg and selenium (Se) biomagnification in an estuarine food web. Estimates of the relationship between total mercury (THg) and methylmercury (MeHg) were significantly improved in mixing model-adjusted food webs over models that included all known prey sources. Spatial differences in dietary composition and MeHg bioavailability offer strong evidence that local food webs can have a significant effect on the biomagnification of Hg within benthic fish species. While no evidence of Se biomagnification was found, lower Se : Hg ratios at higher trophic levels could be attributed to increasing trophic Hg concentration. Furthermore, stable isotope analysis suggested Hg and Se biotransfer from benthic sources to fish. Overall, the findings highlight that isotope mixing models can be a significant aid in assessments of contaminant biomagnification, particularly when it is important to define food pathways to top predators.

History

Publication title

Limnology and Oceanography

Volume

59

Issue

4

Pagination

1181-1192

ISSN

0024-3590

Department/School

Institute for Marine and Antarctic Studies

Publisher

Amer Soc Limnology Oceanography

Place of publication

5400 Bosque Blvd, Ste 680, Waco, USA, Tx, 76710-4446

Rights statement

Copyright 2014 Association for the Sciences of Limnology and Oceanography

Repository Status

  • Open

Socio-economic Objectives

Assessment and management of terrestrial ecosystems

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