Human Shadows on the Seas
Now scientists are building the first worldwide portrait of such dispersed human impacts on the oceans, revealing a planet-spanning mix of depleted resources, degraded ecosystems and disruptive biological blending as species are moved around the globe by accident and intent.
A paper in the Feb. 15 issue of the journal Science is the first effort to map 17 kinds of human ocean impacts like organic pollution, including agricultural runoff and sewage; damage from bottom-scraping trawls; and intensive traditional fishing along coral reefs.
About 40 percent of ocean areas are strongly affected, and just 4 percent pristine, according to the review. Polar seas are in the pristine category, but poised for change. Some human impacts are familiar, like damage to coral reefs and mangrove forests through direct actions like construction and subtler ones like the loss of certain fish that shape ecosystems.
Others were a surprise, said Benjamin S. Halpern, the lead author and a scientist at the National Center for Ecological Analysis and Synthesis in Santa Barbara, Calif. He said continental shelves and slopes proved to be the most heavily affected areas, particularly along densely populated coasts.
Link
No comments:
Post a Comment