Stable isotope ratios of carbon, nitrogen and sulphur and mercury concentrations as descriptors of trophic ecology and contamination sources of Mediterranean whales
[en] The Mediterranean Sea remains a complex system for mercury (Hg) cycling and accumulation in marine vertebrates. The extremely high levels these animals present demand for an urgent understanding of such processes and the development of new analytical techniques that go beyond the simple contamination monitoring. It was often proposed that prey selection or habitat use may affect Hg contamination in animals; however, it was never possible to measure which factor influences more rates and pathways of contamination. In this paper, we directly integrate toxicological information (Hg levels) and ecological tracers (stable isotopes of C, N and S) into a common data analysis framework (isotopic niches), with the aim of quantifying the influence of species’ trophic behaviour on Hg contamination. The analysis was conducted on skin biopsies of fin whales Balaenoptera physalus, long-finned pilot whales Globicephala melas and sperm whales Physeter microcephalus. Their different trophic modes and residency in the area make them model species for the analysis of Hg accumulation along NWMS food webs. We measured Total Hg (T-Hg) concentrations through absorbance spectrometry with the DMA80 Milestone. Carbon, nitrogen and sulphur isotope compositions were measured via mass spectrometry in an IRMS coupled to an Elemental Analyser (EA) Isoprime.
Comparison of ecological and contamination niches allowed to explain Hg accumulation in Mediterranean marine predators. Factors such as food web complexity, trophic position, hunting distribution or habitat use (e.g., foraging depth) did not influence Hg exposure. It is rather the selection of prey type, which determines the range of potential Hg sources and as a consequence the rates of accumulation in whales’ tissues. A generalist piscivorous species such as the pilot whales will bioaccumulate more Hg than specialised sperm whales feeding mostly on cephalopods.
Research Center/Unit :
FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
Disciplines :
Environmental sciences & ecology
Author, co-author :
Pinzone, Marianna ✱; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
Damseaux, France ✱; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
Michel, Loic ; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
Das, Krishna ; Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Océanographie biologique
✱ These authors have contributed equally to this work.
Language :
English
Title :
Stable isotope ratios of carbon, nitrogen and sulphur and mercury concentrations as descriptors of trophic ecology and contamination sources of Mediterranean whales
Publication date :
December 2019
Journal title :
Chemosphere
ISSN :
0045-6535
eISSN :
1879-1298
Publisher :
Elsevier, Oxford, United Kingdom
Volume :
237
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique WWF France - Fonds mondial pour la nature WWF France - Fonds mondial pour la nature
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