‘This work shows that human-released mercury has reached and entered foodwebs in even the most remote marine ecosystems on earth,’ researcher says

Man-made mercury pollution has reached the bottom of the deepest part of the ocean, scientists have discovered.

Two groups of scientists from China and the US found toxic mercury in fish and crustaceans living more than 11,000 metres below the surface of the ocean in the Mariana Trench.

“This is a surprise” said Dr Ruoyu Sun, who led a group of researchers from Tianjin University in China. “Previous research had concluded that methlymercury was mostly produced in the top few hundred meters of the ocean.

“This would have limited mercury bioaccumulation by ensuring that fish which forage deeper than this would have had limited opportunity to ingest the methylmercury. With this work, we now believe that isn’t true”.

Mercury can become concentrated in marine organisms as small amounts are ingested by some species which in turn are eaten by larger species, resulting in more harmful concentrations of the liquid metal accumulating in animals higher up the food chain.