Dolphins in Europe are still threatened by toxic chemicals banned as far back as the 1980s. The new study, published today in the journal Scientific Reports, also involved Morigenos researchers.
The research, based on long-term studies of more than 1,000 stranded or biopsied whales, dolphins and porpoises – collectively known as cetaceans – 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 polychlorinated biphenyls (PCBs) on the planet.
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 and specialist wildlife veterinarian at ZSL’s Institute of Zoology, 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.
“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.”
The research also identifies 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.
The waters off the Slovenian coast and elsewhere in the northern Adriatic Sea are no exception, as research included dolphins living there. Co-author and Morigenos president Tilen Genov said: “PCB concentrations in dolphins that we have been studying for the past 14 years are also fairly high. They aren’t the highest among those studied, but nevertheless worrisome. Almost all of them exceed the levels known to cause physiological effects.”
“Co-author Robin Law said: “Our research underlines the critical need for global policymakers to act quickly and decisively to tackle the lingering toxic legacy of PCBs, before it’s too late for some of our most iconic and important marine predators.”
The study has already been featured in The Guardian, Independent, BBC, Daily Mail, ScienceNews and others.
Paper entitled ’PCB pollution continues to impact populations of orcas and other dolphins in European waters’ is available at: http://www.nature.com/articles/srep18573.