Antarctic Marine Environment Found to Have High Levels of Mercury
09.01.2012 - Water & Oceans, Flora & Fauna, Antarctic
Seabirds in the Southern Ocean have mercury levels four times that of seabirds found elsewhere on the planet, according to research conducted by a team of French and Australian oceanographers led by Daniel Cossa from the French Institute of Recherche for the Exploitation of the Sea (IFREMER).
Previous measurements had found that methylmercury, a toxic form of mercury, was abundant in the tissues of predatory seabirds such as albatrosses and petrels, which feed on fish from the Southern Ocean. It is thought that albatrosses and petrels have adapted to cope with higher levels of mercury, as levels of the toxin were found to be high enough to kill other species of birds.
As Antarctic waters were thought to be more pristine than waters in other regions on the planet, the origin of the contamination remained a mystery until recently. However samples collected aboard the Australian Antarctic Division (AAD) research vessel Aurora Australis during a 2008 expedition found that the methylmercury comes from upwelling of ocean currents. Bacteria deep in the ocean convert mercury originating from anthopogenic pollution into highly toxic methylmercury, and when this water upwells, it enters the bodies of marine species living closer to the ocean surface.
Once mercury enters the food web, the toxin can be found in higher concentrations the farther up the food web one goes. This is a particular concern for humans, as many marine species in the Southern Ocean are exploited for human consumption.
