More Mercury Accumulates in Ocean Fish, Says Study
It has lately been discovered by a collaboration of researchers at the University of Michigan and University of Hawaii, Manoa that accretion of mercury in fish occurs at deeper depths.
As per the findings, the atmosphere carries the mercury before it falls on the ocean, forming the marine food web's part. Thereafter, the photochemical reactions cause the fish to accumulate more mercury at depth. Since, these reactions disintegrate organic mercury in the surface waters.
An earlier study had found that the predatory fish, including opah and swordfish, feeding at deeper depths, had high levels of mercury concentrations. In comparison to them, the fish feeding in waters close to the surface had lower mercury concentrations. These fish could include yellowfin tuna and mahi-mahi.
Hawaii University's Professor of geology and geophysics, Brian Popp, said that the information was known to be true. However, the reason was not known until the latest study.
It is being said that atmospheric mercury is transformed by bacteria in the oceans into organic monomethylmercury form. The same could collect in fish.
"We knew that organic and inorganic mercury dissolved in seawater has a nutrient-like profile, with lower concentrations at the surface and higher concentrations at depth", said PhD candidate in oceanography, Anela Choy.