Persistent Substances Threaten The Health Of Orcas In Iceland

In a new study conducted by marine biologists from Iceland, Canada and Denmark, it has been found that orcas near Iceland are at risk of being poisoned by polychlorinated biphenyl (PCBs).

Nine times more persistent substances were found in Icelandic orcas that eat both fish and mammals than those that eat only fish.

Whale, that’s a bummer

Polychlorinated biphenyl (PCBs) are persistent substances that were used in various industries and even to dust roads in the 20th century.

Their use was banned in the late 1980s when it was discovered that PCBs could harm human health and the environment.

PCB’s have been degrading for years and the effects of it are still seen across the globe today, even being found in organisms in the Arctic.

Our new paper measures contaminants in orcas sampled in Iceland. It finds large within-population variation that relates to known variations in diet preferences and raises concerns for mixed diet whales. Congratulations @AnaRemili and co-authors👏 https://t.co/hTSanOlc5F

— Icelandic Orca Project (@icelandic_orcas) March 24, 2021

Filipa Samarra, an expert at the University of Iceland Research Center in the Westman Islands, says, “The substances have been banned for a long time, but it is very difficult to get rid of them. Eventually they leak into the ocean ecosystem and it is very difficult to get rid of them once they get there. They accumulate in algae, then fish, and they then accumulate throughout the food chain.”

Filipa has been working on the longest continuous study of orcas in Iceland called the Icelandic Orca Project in recent years.

In doing so, scientists have been observing the orcas, taking pictures of them and compiling them into a file that is accessible online.

A new study by Filipa and her colleagues at the Marine Research Institute and the Canadian and Danish universities indicates that animals that eat other marine mammals are at greater risk from PCBs than those that eat only fish. They described their findings in an article in the scientific journal Environmental Science and Technology.

Damaging the health of the killer whales

The effects of PCBs on orcas health in particular are not known exactly. Research on other mammals suggests that they may weaken their immune systems and reduce their reproduction. It is believed that this also applies to marine mammals.

“They may make them less fertile and when they have calves they may not survive,” says Filipa. The weakening of the animals’ immune systems could also shorten their life expectancy.

Animals at the top of the food chain, such as orcas, absorb even more PCBs than animals below it. Seals and dolphins, which are eaten by orcas, feed on fish. They live relatively long and in the meantime the toxins accumulate in them.

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