A big fat source of mercury (Image: Frans Lanting/Mint Images/SPL)
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SEAL fur may be toxic. Mercury is building up even in pristine areas, and it鈥檚 coming from an unexpected source 鈥� moulting elephant seals.
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Industrial pollution can release mercury into the environment, where it may end up as an organic compound called methylmercury. This is taken up by bacteria, and it builds up in organisms much higher up the food chain, including top predators such as elephant seals.
But it doesn鈥檛 end there. 鈥淓lephant seals undergo a catastrophic moult,鈥� says of San Diego State University in California. 鈥淚t comes off in big sheets of fur and the top few layers of skin.鈥�
Cossaboon has traced mercury in California鈥檚 coastal A帽o Nuevo State Park to moulting seals. She calculates that each year seals in the US and Mexico release a similar amount of methylmercury as enters San Francisco bay. Around 40 per cent of California, the most populous US state, drains into the bay, including areas of heavy industry (PNAS, ).
It isn鈥檛 yet clear if methylmercury in the seal鈥檚 coats can work its way back into the food chain, but if it can, then hair and feathers shed from other species may be releasing mercury into food webs, too.
鈥淲e鈥檙e opening the methylmercury era,鈥� says Amina Schartup of Harvard University. 鈥淲e鈥檙e going to uncover more and more things that we didn鈥檛 realise were out there.鈥�
This article appeared in print under the headline 鈥淢oulting seals shed mercury too鈥�
