Assessment of antropogenic contaminants in bottlenose dolphins ("Tursiops truncatus")

Résumé

In the last decades, pollution has become a global problem affecting different species of marine animals. Particularly cetacean populations accumulate high concentrations of anthropogenic contaminants due to their top trophic position, which made them especially vulnerable to long-term toxicity including immune suppression, reproductive impairment and carcinogenic effects. Extensive research on pollutant levels in marine mammals has been reported worldwide, however, little information is available concerning cetaceans from the Canary waters. The present thesis focused on bottlenose dolphin (Tursiops truncatus), species proposed as a bioindicator of the contamination of the Canary Islands. The main objective of this study is to gain a greater understanding of the toxicological status of common bottlenose dolphin in the Canary Islands, as part of the international Macaronesia Cetacean Health Network. To address this objective, the assessment of the levels of 57 persistent organic pollutants (POPs) and 12 toxic trace elements in blubber and liver of bottlenose dolphins stranded from 1997 to 2013 and also POPs in biopsies from live individuals collected during the period of 2003-2011 were conducted. This thesis aimed to compile three articles published in peer-reviewed journals describing the results and interpretation of the toxicological analyses conducted. According to the results of this thesis, the bottlenose dolphin inhabiting the Canary waters is facing a significant exposure to anthropogenic pollutants, highlighting the need for on-going monitoring of contaminant accumulation in cetaceans from this marine area. In general, xenobiotic levels in this species were slightly higher than those from the North Sea and comparable to Western Atlantic Ocean, several locations in the Pacific Ocean and the waters surrounding the UK. As expected, the results obtained were much lower than those observed in the Mediterranean Sea where bottlenose dolphins accumulate great burdens of chemical residues. Further studies are needed to investigate potential associations between contaminants and health status to determine the impact of anthropic environmental pollution on these animals.