Monitoring levels of polychlorinated biphenyls (PCBs) in three cetacean species stranded in Galicia (Spain), NE Atlantic

Despite increasing regulations on their production and use, organic pollutants, such as polychlorinated biphenyls (PCBs), continue to pose a threat to marine life. Odontocete cetaceans are highly susceptible to the accumulation and biomagnification of PCBs due to their role as predators and long life expectancy. Therefore, assessing the levels of PCBs in cetaceans is important to evaluate their health status at the individual and population levels, as well as to provide an indicator of ecosystem health. In the present study, concentrations of PCBs were analysed in the blubber of the three most frequently stranded odontocete species in NW Spain (NE Atlantic): common dolphin (Delphinus delphis) (n = 42), bottlenose dolphin (Tursiops truncatus) (n = 17) and harbour porpoise (Phocoena phocoena) (n = 19). Individual concentrations ranged from 0.32 to 160.74 μg/g lipid weight (l.w., Σ14PCBs), with the highest levels observed, by far, in bottlenose dolphins (the median concentration was three times higher than that of other species). Many observed values exceed the agreed threshold value for these species (17 μg/g l.w., when expressed as the Aroclor 1254 equivalent concentrations). This suggests that a high percentage of the individuals analysed are at risk from PCBs despite an apparent global decrease in environmental levels. The three species analysed are representative of a key area of the NE Atlantic and represent different trophic and habitat niches. Regular monitoring of pollutant levels in cetacean species is necessary for compliance with legislative requirements and to allow the assessment of these populations and their ecosystems.