High pollutant exposure level of the largest European community of bottlenose dolphins in the English Channel

Cyrielle Zanuttini,Krishna Das,Jean-Pierre Thomé,Gauthier Eppe,Georges Scholl,François Gally

doi:10.1038/s41598-019-48485-7

Cyrielle Zanuttini, Krishna Das + Show 4 more

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https://doi.org/10.1038/s41598-019-48485-7

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Abstract

The objective of this study was to assess the levels of persistent organic pollutants (POPs) and mercury (T-Hg) in the blubber and skin, respectively, of the free-ranging bottlenose dolphins, Tursiops truncatus, from the Normanno-Breton Gulf, one of the largest identified coastal population in Europe. Among all the POPs analysed in this study, the ∑NDL-PCBs were the most abundant compounds found in the blubber (mean: 1.33 × 105–0.65 × 105 ng.g−1 lipid weight (lw) for males and females respectively), followed by ∑DDX (1.11 × 104–4.67 × 103 ng.g−1 lw) > ∑DL-PCBs (8.06 × 103–2.62 × 103ng.g−1 lw) > ∑PBDEs (1.95 × 103–0.64 × 103ng.g−1 lw) > dieldrin (1.86 × 103–0.18 × 103 ng.g−1 lw) > ∑endosulfan (405–62 ng.g−1 lw) > HCB (86–52 ng.g−1 lw) > ∑HCHs (47–60 ng.g−1 lw) > ∑chlordane (24–0.97 ng.g−1 lw) > ∑PCDFs (0.3–0.1 ng.g−1 lw) > ∑PCDDs (0.06–0.05 ng.g−1 lw). The T-Hg concentrations were highly variable between individuals (2.45 × 103 ng.g−1 to 21.3 × 103 ng.g−1 dry weight, dw). The reported concentrations are among the highest reported for cetaceans. We strongly recommend that the Normanno-Breton Gulf be a special area of conservation (cSAC) candidate because it contains the last large European population of bottlenose dolphins (rare or threatened within a European context) designated under the EC Habitats Directive.

Highlights

Most organochlorinated contaminants were banned in developed countries in the 1970s and 1980s
Biopsy samples of skin and blubber were collected from 82 bottlenose dolphins from the Normanno-Breton Gulf (NBG) in the English Channel to assess the concentrations of a large range of industrial compounds, dioxin-related compounds (DRCs) and organochlorinated pesticides: NDL-Polychlorinated biphenyls (PCBs) and DL-PCBs, PBDEs, DDXs, HCHs, HCB, PCDDs, PCDFs, cis-chlordane, trans-chlordane, α-endosulfan, β-endosulfan, endosulfan-sulfate, and dieldrin, in the blubber
Among all the persistent organic pollutants analysed in this study (Tables 1 and 2 and Table S2, Supplementary Information), the ∑NDL-PCBs were the most abundant compounds found in the blubber, followed by ∑DDX > ∑DL-PCBs > ∑PBDEs > dieldrin > ∑endosulfan > HCB > ∑HCHs > ∑chlordane > ∑PCDFs > ∑PCDDs

Summary

Introduction

Most organochlorinated contaminants were banned in developed countries in the 1970s and 1980s Their persistent chemical properties favour their long-range transport and remanence in water, air and biota, including the deepest ocean fauna. The bottlenose dolphin is a relevant species for examining environmental contamination trends in coastal areas: The species is widely distributed in estuarine and nearshore waters, is a long-lived species with a high trophic position in the marine food web and a thick layer of blubber in which lipophilic pollutants accumulate. Quantifying the baseline concentrations and patterns of POPs and total mercury (T-Hg) in bottlenose dolphin populations is critical for risk assessment and long-term management. These organic chemical substances are classified as persistent organic pollutants by the Stockholm Convention

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