ocean blue project logo

Methylmercury Levels Are on the Rise in Oceans Across the World


Methylmercury Levels Are on the Rise in Oceans Across the World

By Maria Bruzhayte

Manufacturing, mining, burning coal, volcano eruptions, and burning fires emit mercury. When it enters the ocean, it becomes methylmercury. This new chemical joins the food chain. Planktons carry it to small fish, then to large fish, then up the food chain all the way to humans. The levels of methylmercury in fish that end up on the dining room table are dangerous to humans. At high concentrations, the chemical can cause neurological damage and cardiovascular risks. Unfortunately, due to human activity and climate change, levels of mercury are on the rise.
Even the deepest ocean trenches aren’t safe from man-made mercury. Airborne mercury, primarily from industrial activity, finds its way into rivers and oceans. Previously, scientists believed that methylmercury sat on the top layers of the ocean. The discovery of man-made methylmercury this deep came as a surprise. It is unnatural for animals to contain mercury in remote parts of the ocean. This proves that human activity pollutes even the most isolated marine environments. Know your local rivers and what causes high mercury fish.

Where does methylmercury come from?

Mercury is a naturally occurring element. When it enters the ocean, it doesn’t pose a threat to marine life. Unfortunately, about two-thirds of the mercury in our oceans comes from man-made activity. Around 160 tons of mercury is released into the air, which is then washed out into the ocean. This staggering figure, along with wastewater dumps, converts into methylmercury.
The process by which mercury converts into methylmercury isn’t well known. Some bacteria that lives on the seafloor produces methylmercury, but the process has not been well studied. There are hypotheses in regards to methylmercury production. It is possible that methylmercury comes from the bottom of the ocean itself. Dead phytoplankton may release it when they die. Microbes may convert mercury to methylmercury in low oxygen environments. These theories are still being explored. Regardless of the conversion process, methylmercury needs plenty of mercury to begin with. A polluted atmosphere and ocean runoff provide more than enough to create methylmercury.

Mercury Pollution In The Environment

Mercury exposure can lead to neurological disorders. Mercury exposure is uncommon. Typically, mercury enters the human body through methylmercury accumulated in fish. Poor fetal development, deficits in motor skills, impaired memory, and learning difficulties are common among communities exposed to methylmercury. These are some of the significant risks to the human population.
Since 1990, levels of mercury in the atmosphere have declined due to regulations imposed on the oil and gas industry. Unfortunately, this has not put a dent in methylmercury production in the ocean. Researchers predict that rising seawater temperatures and overfishing correlate with increased methylmercury levels.
There are ways to reduce methylmercury in the ocean. According to Elsie Sunderland, the Gordon McKay Professor of Environmental Chemistry, “Climate change is going to exacerbate human exposure to methylmercury through seafood, so to protect ecosystems and human health, we need to regulate both mercury emissions and greenhouse gases.” New regulations and fishing guidelines are necessary to decrease methylmercury levels.

What can we do?

It is important to consume fish that come from sustainable fisheries. Doing so helps reduce ocean pollution because it doesn’t contribute to overfishing. Sustainable fisheries don’t interrupt the food chain that causes methylmercury to accumulate in large fish.
It’s important to be aware of where our fish comes from. Reading labels and shopping sustainably can help. By becoming aware of fishing sources, we can aid in methylmercury reduction. Educating ourselves about overfishing and ocean pollution is a step in the right direction. 

Consider participating in a Ocean Cleanup Volunteer Beach Cleanup. This helps prevent microplastic pollution. Learn more about Ocean Blue Project to find ways you can get involved. We publish environmental news on our blog about pollution, sustainability, and marine life. Read How Grassroots Organizations Are Playing A Role in Reducing Waste to stay informed.

Author Bio: Maria Bruzhayte is a Los Angeles based writer, animator, and a contributor to the Ocean Blue Project blog.

How you can help support the Ocean Cleanup