Fish populations appear to recover rapidly from mercury pollution once humans stop adding it to their environment. A 15-year study of a lake in Canada found that eight years after the metal’s supply ceased, concentrations of methylmercury – a highly toxic substance made from mercury by bacteria in aquatic ecosystems – fell by 76 per cent…
“I can’t imagine a much faster recovery,” says Paul Blanchfield at government agency Fisheries and Oceans Canada, who led the research. The team are not suggesting the fish excrete the mercury quickly – the experiment in fact shows they hang on to it for a long time – but that quick turnover of generations sees concentrations fall fast when new pollution stops.
Mercury pollution is still a major global environmental problem, with small-scale gold mining and coal burning being the two biggest sources. Transported in the atmosphere and rained down on lakes and oceans, the metal’s accumulation in freshwater and marine species has raised concerns over the human health impact of eating fish.
Excerpts from Adam Vaughan, Freshwater fish can recover from mercury pollution in just a few years, New Scientist, Dec. 15, 2021