A highly toxic form of mercury could jump by 300 to 600 percent in zooplankton – tiny animals at the base of the marine food chain – if land runoff increases by 15 to 30 percent, according to a new study.
And such an increase is possible due to climate change, according to the pioneering study by Rutgers and other scientists published today in Science Advances.
“With climate change, we expect increased precipitation in many areas in the Northern Hemisphere, leading to more runoff,” said Jeffra K. Schaefer, study coauthor and assistant research professor in Rutgers’ Department of Environmental Sciences. “That means a greater discharge of mercury and organic carbon to coastal ecosystems, which leads to higher levels of mercury in the small animals living there. These coastal regions are major feeding grounds for fish, and thus the organisms living there serve as an important source of mercury that accumulates to high levels in the fish people like to eat.”
A highly toxic form of mercury could jump by 300 to 600 percent in zooplankton – tiny animals at the base of the marine food chain – if land runoff increases by 15 to 30 percent, according to a new study.
And such an increase is possible due to climate change, according to the pioneering study by Rutgers and other scientists published today in Science Advances.
“With climate change, we expect increased precipitation in many areas in the Northern Hemisphere, leading to more runoff,” said Jeffra K. Schaefer, study coauthor and assistant research professor in Rutgers’ Department of Environmental Sciences. “That means a greater discharge of mercury and organic carbon to coastal ecosystems, which leads to higher levels of mercury in the small animals living there. These coastal regions are major feeding grounds for fish, and thus the organisms living there serve as an important source of mercury that accumulates to high levels in the fish people like to eat.”
The study showed that an increase in natural organic matter entering coastal waters can boost the bioaccumulation of methylmercury – a highly toxic chemical found at elevated levels in many species of fish – in zooplankton by 200 to 700 percent. The huge increase in methylmercury shifts the food web from being autotrophic (largely microscopic plants and cyanobacteria that make food from inorganic matter) to heterotrophic (bacteria that eat organic matter produced by plants and cyanobacteria).
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Photo: Erik Björn of Umeå University in Sweden injects small amounts of enriched mercury isotopes into sediments for the experiment.
Photo credit Sofi Jonsson
