Mercury Threatens Antarctic Wildlife

A gunshot interrupts the peaceful sleep of a leopard seal, lying nonchalantly on a small piece of ice floating in the shadow of an Antarctic glacier. 

Researcher Diego Mojica lowers his rifle.

The mammal, one of the largest predators on the White Continent after the orca, flinches from the impact of the remote biopsy -- a small red pipette that bounces off its skin, taking with it a piece of flesh -- and swims away.

Mojica, a Colombian marine biologist, descends from his boat alongside Livingston Island, in the South Shetland archipelago, to retrieve his sample.

Mojica is studying the impact of mercury, used in activities such as mining thousands of kilometers away, on Antarctica's large mammals.

The toxic heavy metal is believed to reach the ocean through rivers or rain, after it "evaporates into the air," said Mojica, who works for Colombia's Malpelo Foundation, which specializes in the study of marine fauna.

Scientists at Spain's University of Murcia have previously found mercury in the feathers of chinstrap penguins on King George Island, the closest point in Antarctica to the Americas.

The pollution appears to extend south to Livingston Island and the Gerlache Strait, a natural channel off Antarctica.

The United Nations Global Mercury Partnership warns that marine mammals, because they are "at the top of the food chain, are particularly susceptible to contamination" by the metal.

Humpback whales consume large quantities of krill, small crustaceans susceptible to mercury contamination.

According to the UN environmental agency UNEP, if an animal consumes mercury, it may suffer "reproductive failure, behavioral changes and may even die."

In 2013, 140 countries signed the Minamata Convention to reduce the use of mercury, which can cause severe health problems.

Some 9,000 tons of the toxic substance are released into the atmosphere every year.

Artisanal mining is the main source of mercury emissions, where the element is used to collect gold by binding to it.