Abstract
Mercury (Hg) is a toxic metal that accumulates in organisms and biomagnifies along food webs; hence, long-lived predators such as seabirds are at risk as a result of high Hg bioaccumulation. Seabirds have been widely used to monitor the contamination of marine ecosystems. In the present study, we investigated Hg concentrations in blood, muscle, and feathers of 7 procellariform seabirds breeding on the Chatham Islands, New Zealand. Using bulk and compound-specific stable isotope ratios of carbon and nitrogen as a proxy of trophic position and distribution, we also tested whether Hg contamination is related to the species-specific feeding ecology. Mercury exposure varied widely within the seabird community. The highest contaminated species, the Magenta petrel, had approximately 29 times more Hg in its blood than the broad-billed prion, and approximately 35 times more Hg in its feathers than the grey-backed storm petrel. Variations of Hg concentrations in blood and feathers were significantly and positively linked to feeding habitats and trophic position, highlighting the occurrence of efficient Hg biomagnification processes along the food web. Species and feeding habitats were the 2 main drivers of Hg exposure within the seabird community. The Pterodroma species had high blood and feather Hg concentrations, which can be caused by their specific physiology and/or because of their foraging behavior during the interbreeding period (i.e., from the Tasman Sea to the Humboldt Current system). These 2 threatened species are at risk of suffering detrimental effects from Hg contamination and further studies are required to investigate potential negative impacts, especially on their reproduction capability. Environ Toxicol Chem 2021;40:454-472. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
Highlights
Mercury (Hg) is a toxic and pervasive metal that occurs naturally in the environment; it is emitted from topsoil, volcanoes, and other geothermal sources (Pirrone et al 2010).anthropogenic activities have substantially modified the cycling of this trace element on a global scale, mainly through the combustion of fossil fuels, industrial and agricultural pollution, waste incineration, and gold mining (Eagles‐Smith et al 2018)
We examined the influence of feeding ecology on Hg exposure using bulk stable isotope ratios of carbon (δ13C) as a proxy of the feeding habitat, and bulk stable isotope ratios of nitrogen (δ15N) and compound‐ specific isotopic analyses of amino acids (CSIA‐AA) as proxies of the trophic position
Blood and feather Hg concentrations varied widely within the Chatham Island seabird community (Table 2), with mean values ranging in blood from 0.40 ± 0.09 μg g–1 dry weight in broad‐billed prions to 11.72 ± 3.58 μg g–1 dry weight in Magenta petrels, and in feathers from 0.49 ± 0.23 μg g–1 dry weight in grey‐backed storm petrels to 34.14 ± 6.83 μg g–1 dry weight in Chatham petrels
Summary
Mercury (Hg) is a toxic and pervasive metal that occurs naturally in the environment; it is emitted from topsoil, volcanoes, and other geothermal sources (Pirrone et al 2010). Anthropogenic activities have substantially modified the cycling of this trace element on a global scale, mainly through the combustion of fossil fuels, industrial and agricultural pollution, waste incineration, and gold mining (Eagles‐Smith et al 2018). In combination, these human‐ induced perturbations are currently responsible for two‐thirds of the global Hg emissions (Pacyna et al 2006).
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