Science & Technology

Global marine patterns of mercury pollution revealed by bluefin tuna

According to research by Ratgers and other institutions, bluefin tuna is a long-lived mobile species that accumulates mercury as it ages and can be used as a global barometer of the risks posed to heavy metals and marine life and human health.

Researchers have studied the accumulation of mercury in mobile species around the world.

According to research by Ratgers and other institutions, bluefin tuna is a long-lived mobile species that accumulates mercury as it ages and can be used as a global barometer of the risks posed to heavy metals and marine life and human health.

Studies will appear in the journal PNAS.

Bluefin tuna, one of the largest and fastest fish species on the planet, is widely distributed in the oceans around the world, but overfishing due to consumer demand has significantly depleted its resources. In addition, muscle tissue contains high levels of neurotoxic methylmercury, which increases with age. Methylmercury is a form of mercury that spreads biologically in aquatic food networks, resulting in neurotoxic concentrations in bluefin tuna meat, often above levels safe for human consumption. However, it is not well understood how mercury accumulation differs among bluefin tuna distributed around the world.

Various types of tuna have been proposed as biological indicators of changes in marine mercury pollution, but in addition to taxonomic differences, the mercury levels in saltwater fish are affected by age and size, so the mercury concentration in fish tissues is determined. It is difficult to make a direct comparison in space and time. , Location within the food web and type and quantity of prey. These depend on the environmental conditions of the region and the earth.

To address these issues and provide a standard basis for comparisons of mercury pollution throughout the world’s oceans, researchers have compared changes in muscle mercury levels among bluefin tuna species from four different marine subbasins. bottom. There are three types of bluefin tuna: the Atlantic Ocean (the largest and most endangered), the Pacific Ocean, and the South. Most of the Atlantic bluefin tuna catch comes from the Mediterranean, the world’s most important bluefin tuna fishery.

After previous studies on muscle tissue samples from 1998 to 2019 and a thorough review of mercury analysis, researchers found that black tuna had the highest mercury accumulation in the Mediterranean, the North Pacific, the Indian Ocean, and the North. Found to decline in the Atlantic Ocean. In addition, mercury accumulation increases in proportion to the concentration of methylmercury in regional seawater and zooplankton, correlating the accumulation of methylmercury in bluefin tuna with the bioavailability of methylmercury at the bottom of the food web in each subbasin. increase.

The observed global patterns correspond to mercury levels in each marine subbasin. The Mediterranean, North Pacific and Indian Oceans are affected by natural processes such as mercury leachation from rocks and human pollution from metal mining, smelting and burning fossil fuels. The Atlantic Ocean is not so much. The study shows that the mercury accumulation rate of bluefin tuna as a global pollution indicator reflects the global circulation of natural and human sources and deep sea currents caused by differences in water density controlled by temperature and salt content. They found.

“Our study shows that the mercury accumulation rate of blue fin tuna is a global pollution indicator that can reveal patterns of mercury pollution and bioavailability in the ocean, natural and anthropogenic emissions, and environmental characteristics of the region. It shows that it can be used as, “said one of the senior authors of the study. John Reinfelder, Professor of Environmental Sciences, Rutgers University, New Brunswick. His research focuses on biogeochemistry of chemical elements in marine and freshwater ecosystems. “Overall, mercury accumulation rates from comparing the bioavailability of mercury between geographically distinct populations of nutrient-rich marine fish across small basins of the ocean and investigating the nutritional dynamics of mercury in marine food networks. Provides a means to improve the public health risk assessment of mercury exposure. Seafood. “

Reference: “Bluefin tuna reveals global patterns of mercury pollution and bioavailability in the world’s oceans by September 2021.” Minutes of the National Academy of Sciences..
DOI: 10.1073 / pnas.2111205118

The study was conducted in collaboration with researchers at National Taiwan University and the University of California, Santa Cruz.



Global marine patterns of mercury pollution revealed by bluefin tuna

https://scitechdaily.com/global-ocean-patterns-of-mercury-pollution-revealed-by-bluefin-tuna/ Global marine patterns of mercury pollution revealed by bluefin tuna

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