Revealed: Polluting impact of humans on the oceans

Scientists found more than 40 per cent of the oceans bear the scars of serious environmental degradation. Photo / Reuters

Almost every part of the world's oceans has been tainted to some extent by the destructive footprint of human activity, whether it is from overfishing and pollution or commercial shipping and coastal development.

For the first time, scientists have compiled a comprehensive map of the oceans showing the extent to which they have been damaged by man.

The map integrates 17 different kinds of human activity - such as nitrogen fertilisers being washed into the sea from farming - and 20 types of ocean ecosystem, from coral reefs to mangrove forests, to study which parts of the marine environment have suffered most.

The scientists found more than 40 per cent of the oceans bear the scars of serious environmental degradation and that only a small percentage have remained as pristine regions free of human influence.

The team of American scientists said the extent of the damage caused by man came as a shock although they believe the information they compiled could be used to improve the conservation and future protection of the marine environment.

The worst affected waters include large areas of the North Sea, the South and East China seas, the Caribbean Sea, the Atlantic off the east coast of North America, the Mediterranean, the Red Sea, the Bering Sea, parts of the western Pacific and the Persian Gulf.

Details of the study were presented yesterday to the American Association for the Advancement of Science in Boston by Ben Halpern of the University of California at Santa Barbara, who led the team of 19 experts from 16 different research centres.

"This project allows us to finally start to see the big picture of how humans are affecting the oceans.

Our results show that, when these and other individual impacts are summed up, the big picture looks much worse than I imagine most people expected.

It was certainly a surprise to me," Dr Halpern said.

"My hope is that our results serve as a wake-up call to better manage and protect our oceans rather than a reason to give up.

Humans will always use the oceans for recreation, extraction of resources and for commercial activity such as shipping.

That is a good thing.

Our goal, and really our necessity, is to do this in a sustainable way so that our oceans remain in a healthy state and continue to provide use the resources we need and want."The worst-affected marine ecosystems were coral reefs, nearly half of which have suffered badly, seagrass beds, mangrove forests in estuaries, underwater "mountain" ranges known as seamounts, rocky reefs and shallow continental shelves, especially those near densely populated areas, such as the North Sea.