Human activities on land and in the water can impact the marine environment. Many research stations continue to release raw or partially separated sewage straight into the water. Bacteria and viruses from the sewage could affect both people and the organisms that live in the water. To make matters worse, some of these bugs may survive in seawater much longer than previously thought.
Sewage flowing into the sea contains high levels of nutrients like nitrates that can overload the marine environment. An overdose of nutrients can upset the balance in the ecosystem. In extreme cases, solid sewage can smother small sections of the sea floor, destroying the habitats of animals that live there. The dumping of chemicals, poisonous metals and detergents can cause untold damage too.
The increase in boat traffic in Antarctic waters has added to the risk of pollution. Intentional discharges of pollutants or rubbish are not allowed and sewage disposal is tightly controlled under the International Convention for the Prevention of Pollution from Ships, which applies in Antarctica. But with growing numbers of fishing boats and cruise ships carrying tourists to the continent, there is always the danger of ships being damaged or sinking.
This is what happened to the Argentine navy transport ship, Bahia Paraiso, on January 28th 1989. The ship was carrying tourists and supplies when it ran aground just three kilometres off the coast of Antarctica. Although no-one on board was injured a ten metre gash in the side of the ship released around 600,000 litres of diesel fuel and other pollutants into the surrounding water. The United States National Science Foundation found that the initial spill killed up to half the molluscs and algae at the water’s edge, but had little effect on life below the water. Some seabirds were affected, especially cormorants, which lost all their chicks that summer. Although the molluscs and algae recovered quickly, the cormorant and kelp gull populations have taken several years to return to normal. Environmentalists have warned that with increased shipping accidents like this are more likely in the future unless action is taken to prevent them.