High amounts of mercury found in western Aleutian Steller sea lions

Published: Nov. 5, 2020 at 4:10 PM AKST
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FAIRBANKS, Alaska (KTVF) - Western Aleutian Steller sea lions have been found to contain large amounts of mercury. In the 1970s and 1980s, the Steller sea lion in the Aleutian islands declined, and in the western islands they were placed on the endangered species list. The fact that mercury can be a neurotoxin has attracted scientists to investigate.

Michelle Trifari, a graduate student in marine biology at the Alaska College of Fisheries and Ocean Sciences told us, “When Steller sea lions of the western population were screened for different chemicals, mercury just lit up and they found there were very high concentrations of mercury specifically in the western Aleutian Islands."

The mercury is not only a concern for adult sea lions but also their offspring.

“It is very concerning, because mercury can be a neurotoxin and female Steller sea lions actually pass the mercury in their body along to their fetuses, so that’s really concerning for a population that you want to grow when now mercury is in all the newborns that are trying to grow and keep the population going”, said Trifari.

There is has not been a confirmed source of the mercury as yet. It is confirmed to be in the prey of the sea lions and continues down the food chain from there, but how it has been introduced to the food web not yet known.

“The problem with mercury is once it is in the atmosphere or released into the atmosphere, it has a very long residence time -- so it can stay in the atmosphere and circulate around the globe before it deposits anywhere,” said Trifari.

The project to find the source of the mercury was funded by the North Pacific Research Board, and Trifari was enthusiastic about the process being used.

“We’re using a cutting edge technique called Stable Isotope Analysis, and this particular analysis is going to allow me to actually map out the food web. Then once we map out the food web we’ll be able to see and trace how much mercury is actually traveling up that food web,” said Trifari.

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