Human activity affecting oceans worldwide, map shows
WASHINGTON - Oceans cover more than 70 percent of the planet, and every single spot has been affected by people in some way, according to researchers who have studied 17 different activities ranging from fishing to pollution. They have compiled a new map showing how and where people have impacted the seas.
The map was released at the annual meeting of the American Association for the Advancement of Science in Boston and published in today's edition of the journal Science.
"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, an assistant research scientist at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara.
The areas most affected include the North Sea, the South and East China Seas, Caribbean Sea, the east coast of North America, the Mediterranean Sea, the Red Sea, the Persian Gulf, the Bering Sea, and parts of the western Pacific, the study found. It said the least affected areas are near the poles.
However, the researchers said it is likely that human activities will more and more affect polar regions as climate change warms those areas.
Damage includes reductions in fish and sea animals, as well as problems for coral reefs, seagrass beds, mangroves, rocky reefs and shelves, and seamounts.
"There were two things we didn't anticipate," Halpern said in a telephone interview. "Every single spot in the oceans was affected by at least one human activity . . . we figured there'd be places people just hadn't gotten to yet."
And "more than 40 percent is impacted by multiple different activities," he added. "The oceans are not in good shape."
Yet Halpern did find room for hope.
"There are some areas in fairly good condition. They are small and scattered, but have fairly low impact," he said. "That suggests that with effort from all of us, we can try to protect these patches and use them as a guideline for what we'd like the rest of the ocean to start looking like."
The 19-member research team mapped the varying impacts on the oceans and then through overlays of the maps they were able to compile which areas were most affected.
Impacts studied by the researchers included the effects of structures such as oil rigs, commercial shipping, species invasion, climate-change impacts including acidification, ultraviolet radiation, and sea temperature, various types of fishing, and several types of human-related pollution.
In a separate paper in the same issue of Science, researchers reported that oxygen levels in some of the shallow waters along the coast of Oregon dropped to virtually nothing for the first time ever in 2006.
The research team led by Francis Chan at Oregon State University said the cause of this change is not yet completely clear, but the findings show how quickly the distribution of oxygen can change. 