Orca whales and other European cetaceans are at risk of extinction due to now banned toxic substances still ending up in the water streams and then the seabed.
The substances referred to in the Zoological Society of London, Institute of Zoology study are known as polychlorinated biphenyl (PCBs). The study collected samples from a large swath of cetaceans common to the European coastal waters.
Over 1,000 orca whales, porpoises and dolphins have been sampled in the large-scale study. Polychlorinated biphenyl substances have been traced in all the cetaceans which were found stranded. Bottlenose dolphins, the striped-nose dolphins and orca whales presented high levels of PCBs in their body.
The toxic chemicals are a health hazard animals and the environment as well. High levels of polychlorinated biphenyl attack the immune system. Orca whales and other European cetaceans are at risk of extinction as a faulty immune system leads to reproductive problems. Breeding levels decrease while newborn calf mortality increases. A combination of these two trends could well lead to extinction. The case in point best illustrating the devastating effects of PCBs is that of European orca whales.
Polychlorinated biphenyl substances are organic compounds which during the 1980s were quite the fashion. Used in industrial materials such construction materials, paints or plastic materials, they were banned and with good reason. The health hazard posed by PCBs has long been studied. The toxic chemicals affect us and wildlife equally. Although they are no longer in use, their effects still linger as materials or waste from the 1980s are degrading and ending up in the wastefill.
Left to degrade in unsealed landfills, PCBs wash into water streams and infiltrate the seabed. From here, there is just one step until the toxic chemicals end up in the food chain of cetacean predators. Orca whales, once a populous species hunting for food along the European coastline are now facing alarming drops in population numbers. Dolphins fare better, yet the situation isn’t more encouraging either.
According to lead author Paul Jepson with the Zoological Society London Institute of Zoology, the situation is in fact bleak. Orca whales in industrialized regions in Europe are in danger. Both orca whales and bottlenose dolphins are apex predators. Typically, they also enjoy a long lifespan. However, the accumulation of PCBs in the food chain is dimming the perspectives of the species.
Despite the ban on the use of polychlorinated biphenyl substances and the scalable results in decreased contamination of the environment, these toxic substances are reaching European cetaceans through the food chain.
The study, published in the journal Nature offers possible solutions to tackle European coastal waters contamination with the toxic substances. Among them the research team urges European governments to enact stronger restrictions on the disposal and storage of materials containing PCBs.
Photo Credits: Wikimedia