Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks - Université de Bretagne Occidentale Access content directly
Journal Articles Marine Pollution Bulletin Year : 2022

Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks

Abstract

Oxygen minimum zones (OMZs) are currently expanding across the global ocean due to climate change, leading to a compression of usable habitat for several marine species. Mercury stable isotope compositions provide a spatially and temporally integrated view of marine predator foraging habitat and its variability with environmental conditions. Here, we analyzed mercury isotopes in blue sharks Prionace glauca from normoxic waters in the northeastern Atlantic and from the world's largest and shallowest OMZ, located in the northeastern Pacific (NEP). Blue sharks from the NEP OMZ area showed higher Δ199Hg values compared to sharks from the north-eastern Atlantic, indicating a reduction in foraging depth of approximately 200 m. Our study suggests for the first time that blue shark feeding depth is altered by expanding OMZs and illustrates the use of mercury isotopes to assess the impacts of ocean deoxygenation on the vertical foraging habitat of pelagic predators.
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Dates and versions

hal-04159128 , version 1 (02-10-2023)

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Gaël Le Croizier, Jeroen E. Sonke, Anne Lorrain, Sandrine Serre, Lucien Besnard, et al.. Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks. Marine Pollution Bulletin, 2022, 181, pp.113892. ⟨10.1016/j.marpolbul.2022.113892⟩. ⟨hal-04159128⟩
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