Levels and profiles of POPs (organochlorine pesticides, PCBs, and PAHs) in free-ranging common bottlenose dolphins of the Canary Islands, Spain

Abstract

The effect of anthropogenic pollution in marine mammals worldwide has become an important issue due to the high concentrations found in many areas. The present study represents the first report of pollutants in free-ranging cetaceans from the Canary Islands, where there are 12 marine Special Areas of Conservation (SACs), because of the presence of bottlenose dolphins (Tursiops truncatus). We selected this resident population of dolphins as a bioindicator to gain knowledge concerning the toxicological status of the cetaceans of this protected area. In 64 biopsy samples of live free-ranging animals sampled from 2003 to 2011, we determined the concentrations of 18 polychlorinated biphenyls (PCBs), 23 organochlorine pesticides (OCPs) and 16 polycyclic aromatic hydrocarbons (PAHs). We found high levels of many of these pollutants, and some of them were detectable in 100% of the samples. The median value for ∑OCPs was 57,104ngg−1 lipid weight (lw), and the dichlorodiphenyldichloroethylene (p,p′-DDE) accounted for 70% of this amount. Among PCBs, congeners 180, 153 and 138 were predominant (82% of ∑PCBs; median=30,783ngg−1 lw). Concerning the analyzed PAHs, the total median burden was 13,598ngg−1 lw, and phenanthrene was the compound measured at the highest concentration followed by pyrene and by naphthalene. Surprisingly, we have found that organohalogen pollutants exhibit an upward trend in recent years of sampling. Thus, according to the guidelines outlined in the EU's Marine Strategy Framework Directive, further monitoring studies in Canary Islands are required to contribute to the conservation of the resident populations of marine mammals in this region.