Could Warmer Ocean Temperatures Raise Mercury Levels in Fish?

First Posted: Oct 03, 2013 06:39 PM EDT

A recent study looks at how rising ocean temperatures could also potentially raise mercury levels in fish, increasing the health risk to those who eat seafood.

According to Dartmouth researchers and colleagues, little has been known about how global warming may affect levels of mercury found in sea creatures or bioaccumulation of marine life. And no previous study has actually demonstrated the effects of using fish in both the laboratory and field experiments. Mercury released into the air via industrial pollution can cause pollutants to accumulate in streams and oceans to turn into methylmercury in the water.

Ingested methylmercury is absorbed by the gastrointestinal tract and mostly found via various amino acids, such as fish. As it easily binds to proteins, it's blood-life in humans is approximately 50 days-at which time it can cause health issue with the human body when overexposure occurs, such as decreased language skills, memory and even an increased risk of autism.

The rising ocean surface temperatures caused by climate change can make fish accumulate more mercury that poses this significant health risk for people who often find nutrients from seafood.

The researchers studied killifish via varying temperatures in a lab in salt marsh pools in Maine. The fish in the marshes lived off a diet of insects, worms and other natural food sources while they were watched. They were also fed mercury-enriched food. Results showed that the fish in warmer waters ate more but grew less and had higher levels of methylmercury levels in their tissues, suggesting an increase in metabolic rate caused by the increased uptake of toxic metal.

More information regarding the study can be found via the journal PLOS One

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