High levels of PCBs threaten whales and dolphins
Scientists are raising serious concerns about the future of whales and dolphins in European waters who are continuing to suffer from the effects of toxic chemicals that were banned decades ago, but continue to linger in the environment.
According to a new study led by the Zoological Society of London (ZSL), which was just published in the journal Scientific Reports, whales and dolphins in Europe have been found to have some of the highest levels of polychlorinated byphenyls (PCBs) in the world.
PCBs were banned globally in the 1980s, but the latest research shows they are still persistent decades later, making their way through the food chain and accumulating in marine predators, who store PCBs in their blubber, at alarming levels.
For the study, scientists tested tissue samples from more than 1,000 live and stranded cetaceans, including porpoises, striped dolphins, bottlenose dolphins and orcas, while the last three were found to have levels above the known toxicity threshold for all marine mammals.
The accumulation of PCBs in their systems can cause big problems for marine mammals by impacting their immune systems and making them far more susceptible to diseases and other health issues, in addition to hindering their ability to successfully reproduce. Mothers can also pass these toxic chemicals to their young when they’re pregnant and nursing.
The study points to the only resident orca pod in the UK, known as the West Coast Community, who have not had a birth in the last two decades. Last week, they tragically lost another member, Lulu, who died after being entangled in fishing gear. Her death leaves just eight members in the pod, along with fears and near certainty that this unique population is going to go extinct.
“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,” said Dr. Paul Jepson, lead author of the study and specialist wildlife veterinarian at ZSL’s Institute of Zoology.
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Dolphin image via Shutterstock.