PCB pollution still impacts populations of orca and other dolphins in European waters

Paper published in Nature-Scientific Reports today by the UK stranding scheme (CSIP) with SMASS and many other international organisations as co-authors. This is an internationally important area of research and shows that PCB pollution still impacts populations of killer whales and other dolphins in European waters”.

The results of an internationally important area of research by the CSIP have been released today. The paper, titled “PCB pollution still impacts populations of orca and other dolphins in European waters” is published in the journal Scientific Reports and describes a multinational, 22 year study into levels of polychlorinated biphenyls (PCBs) in a number of cetacean species around Europe. This long-term dataset (1990-2012) represents one of the world’s largest studies of marine contaminants in cetaceans. We found that the blubber of killer whales (Orcinus orca), bottlenose dolphins (Tursiops truncatus) and striped dolphins (Stenella coeruleoalba) in Europe contain among the highest concentrations of PCBs on the planet. Some populations of killer whales in European waters may therefore be facing extinction, as a result of the impact from these lingering toxic chemicals, which have been banned since the 1980s.

PCBs are a group of man-made chemicals previously used in the manufacture of products including electrical equipment, flame retardants and paints. High exposure to PCBs is known to weaken cetacean immune systems and markedly reduce breeding success by causing abortions or high mortality in newborn calves.

Dr Paul Jepson, lead author of the study and lead pathologist within the CSIP, said “The long life expectancy and position as apex or top marine predators make species like killer whales and bottlenose dolphins particularly vulnerable to the accumulation of PCBs through marine food webs. Our findings show that, despite the ban and initial decline in environmental contamination, PCBs still persist at dangerously high levels in European cetaceans.”

The research also identified locations around Europe as particular global PCB ‘hotspots’, including the western Mediterranean Sea and south-west Iberian Peninsula. Concentrations of these chemicals tend to remain higher near industrial areas and densely-populated urban centres, making European waters especially vulnerable.

Dr Jepson also said “Few coastal orca populations remain in western European waters. Those that do persist are very small and suffering low or zero rates of reproduction. The risk of extinction therefore appears high for these discrete and highly contaminated populations. Without further measures, these chemicals will continue to suppress populations of orcas and other dolphin species for many decades to come.”

www.nature.com/articles/srep18573

foto credits: Orca stranding in the River Mersey, 2001, CSIP/ZSL