First Map of Human Impacts on Oceans Released

Oceans span nearly three quarters of the Earth's surface and despite this vast size hardly a square kilometre has been untouched by humans.

Researchers released the first-ever global map of human impacts on oceans in the journal Science. Impacts ranged from fishing to pollution to ship transportation.

"There really aren't any areas without human impacts," said Kimberly Selkoe, a principal investigator on the project and a post-doctoral researcher at the University of Hawaii.

"The most shocking message here is that we don't actually have a lot of data on human impacts," Selkoe told IPS.

Scientists could only use available data -- and there isn't any information on illegal fishing, climate change impacts, marine debris, and historical fishing impacts, among many others. Scientists could only get data on less than 10 percent of the total ocean-going ship traffic.

"Even then there is hardly an area of the ocean that isn't criss-crossed by ship tracks on our map," Selkoe said.

The study reports that the most heavily affected waters in the world include large areas of the North Sea, the South and East China Seas, the Caribbean Sea, the east coast of North America, the Mediterranean Sea, the Red Sea, the Persian Gulf, the Bering Sea, and several regions in the western Pacific. The least affected areas are largely near the poles.

Past studies of human impacts on the ocean -- rarely conducted on a global scale -- have focused largely on single activities or single ecosystems in isolation. In this study scientists examined the cumulative influence of human activities across the entire ocean.

"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," said lead author Ben Halpern, Assistant Research Scientist at National Centre for Ecological Analysis and Synthesis (NCEAS) at the University of California at Santa Barbara.

An important new finding is that human influence on the ocean varies dramatically across ecosystems. The most heavily affected areas include coral reefs, seagrass beds, mangroves, rocky reefs and shelves, and seamounts. The least impacted ecosystems are soft-bottom areas and open-ocean surface waters.

The remotest parts of open ocean are still far from pristine.

An estimated 100 million tonnes of trash is floating in the middle of the North Pacific. This vast sea of plastic garbage stretches for thousands of kilometres -- north of Hawaii to Japan -- covering an area twice that of the U.S. Everything from fishing gear to water bottles to plastic bags are found here says Bill Macdonald of the Algalita Marine Research Foundation -- a Long Beach, California-based non-profit environmental organization. Oceanographer Charles Moore, discovered this garbage patch in the 1990s and started the Foundation to do research on the problem of marine debris.

"It's getting worse and worse over the years," Macdonald told IPS.

The Foundation's solar-powered research vessel Alguita is currently in the middle of the plastic flotilla taking samples. Cleanup is impossible, not only because of the huge volume of debris, but also because lots of marine creatures like shellfish and algae latch onto the floating islands of plastic, Macdonald says.

The Alguita has discovered that tendrils of debris extend up to 100 meters below the surface, according to Macdonald.

Not only does plastic kill marine animals that eat it or get tangled in it and drown, but it also damages and degrades their habitat. Plastic pellets are also magnets for toxic chemicals, becoming, in effect, poison pills.

Most plastics do not biodegrade. Unless removed, they will remain in the sea for hundreds of years, breaking up into ever-smaller particles. "In Hawaii on isolated beaches that no one cleans up, two-foot deep sand is actually 80 per cent plastic bits now," says Macdonald.