IIT-H and Harvard University researchers study mercury accumulation in fish

Climate change and overfishing are resulting in an increase of a toxin called methyl mercury (MeHg) in fish of the oceans. A joint research conducted by the Indian Institute of Technology, Hyderabad (IIT-H), Harvard University, and Fisheries and Oceans Canada, a Canadian government agency, has found ‘how climate change impacts mercury accumulation in fish’. Though there has been a decrease in the levels of mercury pollution, the amount of mercury found in fish have been different in different species- some types of fish have less mercury than before, and some alarmingly more. 

This seminal work has been published in the August 2019 issue of the prestigious international peer-review journal Nature. The Research was led from India by Dr. Asif Qureshi, Associate Professor, Department of Civil Engineering, IIT Hyderabad, and co-authored by Dr. Amina Schartup, Dr. Colin Thackray. Dr. Clifton Dassuncao, Dr. Kyle Gillespie, Dr. Alex Hanke and Dr. Elsie Sunderland. Using data collected over the last 30 years and ecosystem modelling, this team of researchers from IIT Hyderabad and Harvard University studied the trend of methyl mercury presence in two predatory fish from the Gulf of Maine in the Atlantic Ocean which are widely consumed by people- Atlantic Cod and Atlantic Bluefin Tuna. Explaining the complexity of the problem, Dr. Asif Qureshi said, “There are three factors that affect mercury accumulation in fish-overfishing, which leads to dietary changes among marine animals, variations in the temperature of the sea water, which leads to changes in fish metabolism that gears towards survival rather than growth, and changes in the amount of mercury found in sea water as a result of pollution.”

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The researchers included all three factors in their modelling studies. 

Our results help to explain why the variations in mercury concentrations have been mixed across different types of fish, despite all reductions in mercury release into the sea since the 1970s,” Dr. Qureshi said.

Methyl mercury can cause severe damage to the nervous system in humans. It occurs in sea, ocean and river water after mercury emitted from various polluting sources, mainly thermal power plants, enters the water and gets converted to methyl mercury, after which it enters the fish

Only by tackling both mercury emissions and global warming, can we reduce levels of mercury in marine animals and our exposure to mercury in seafood.

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