Ecology: Predicting the recovery of mercury-contaminated fish populations
Nature reports that reducing mercury pollution in lake ecosystems reduces methylmercury pollution in fish within just a few years.Our findings suggest that efforts to curb mercury emissions can reduce the risk of human exposure to mercury through fish consumption.
Mercury excreted as a result of human activity enters the aquatic ecosystem, where it is converted to methylmercury.Methylmercury is a powerful neurotoxin that accumulates in fish and threatens human health.Our understanding of how effective reducing mercury emissions is in removing the pollutant methylmercury from the food chain is limited.Now, Paul Blanchfield and colleagues conducted a 15-year whole ecosystem experiment to directly assess the impact of mercury regulatory measures on the recovery of fish pollution.
During the first seven years of the experiment, Blanchfield and colleagues supplied methylmercury with mercury isotopes (to directly monitor mercury addition) to Canada's secluded, undisturbed lakes and their basins. It was recorded that the isotope-labeled mercury was ingested by fish in this aquatic ecosystem.Methylmercury levels increased by 7-45% in invertebrates (such as plankton) and small fish (such as yellow perch) and by more than 57% in large fish populations such as kawakamas and whitefish.After that, the supply of mercury isotopes was stopped, and the observation of the effects on the food chain was continued for eight years.The concentration of labeled methylmercury decreased rapidly in small fish, and by the end of the test period the concentration had decreased by more than 40%.This triggered a decrease in the concentration of labeled methylmercury in large fish, with a 8% decrease in the pike population and a 85% decrease in the whitefish population.
Blanchfield et al. Conclude that the rapid reduction in methylmercury contamination observed in this experiment underscores the potential for increased safety of fish consumed by humans by controlling mercury emissions.
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Reprinted from: "Ecology: Predicting the recovery of mercury-contaminated fish populations'
