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Antarctic Mercury Threatens Fish and Birds

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Bacteria in Antarctic sea-ice can change mercury into a more toxic form that can contaminate the marine environment, including fish and birds, according to a study published in Nature Microbiology.

Mercury can be released into the environment through volcanic eruptions and re-released from vegetation during bushfires, as well as through human activities such as gold smelting and fossil fuel combustion.

Caitlin Gionfriddo, a PhD candidate at The University of Melbourne who spent 2 months aboard the icebreaker Aurora Australis to collect samples of Antarctic sea-ice during an expedition mounted by the Australian Antarctic Division, says that methylmercury is an even more toxic form that accumulates in the food web.

“Larger fish eat smaller contaminated fish and continuously accumulate methylmercury at harmful levels for human consumption,” Gionfriddo said. Methylmercury ingested by people can travel to the brain, causing developmental and physical problems in foetuses, infants and children.

The sea-ice was analysed for different forms of mercury, including methylmercury, as well as the DNA and proteins from sea-ice microorganisms. Team leader Dr John Moreau said that the results confirmed the presence of sea-ice bacteria that could convert mercury into the more toxic methylmercury form.

The findings highlight the importance of eliminating...

The full text of this article can be purchased from Informit.