Troubled waters, coast to coast

A new study by a team of US experts finds that only four per cent of the world’s oceans are still pristine, reports Aditya Ghosh.

Only four per cent of the world's oceans are still pristine, says a new study by a team of US experts.

In India, the maximum damage is along the coasts of Mumbai, Kolkata, Coimbatore and Chennai, found a team led by Benjamin Halpern of the National Center for Ecological Analysis and Synthesis in California.

The researchers compiled data on 17 different ways humans impact oceans, including fishing, coastal development, fertiliser runoff, depletion of coral reefs and shipping.

To provide a holistic analysis, the team plotted a map detailing how the human impact would add up to affect 20 types of ecosystems. About 41 per cent of the world's oceans bear a serious human "footprint."

Indian coasts suffered heavily due oil pollution as the Indian Ocean provides passage to 70 per cent of the world's oil trade, said Baban Ingole, a biological oceanography expert at the National Institute of Oceanography (NIO), Goa. Destruction of reefs, a major problem across India, is also causing massive damage.

Added Mita Banerjee, deputy director (western region), Ministry of Environment and Forests: "We confiscate enormous amounts of coral that is being smuggled out. We have a major marine ecology problem."

Adding to the worries is highly-polluted water from estuaries, said RK Sarma, scientist in charge at NIO's Mumbai centre.

Globally, human influence runs deepest in the North Sea, the South and East China Seas, the Caribbean, the Mediterranean, the Red Sea, the Persian Gulf, the Bering Sea, along the eastern coast of North America and in the western Pacific.

The oceans around the poles have been affected very little, but dwindling polar ice sheets will leave them vulnerable in the future, research suggests.

Impact on ecosystems was measured taking into account the vulnerabilities of each.

The ocean was broken down into square kilometres — 361 million of them — each measured as per its ecosystem and the human impact on it.