The first comprehensive analysis of human impacts on marine ecosystems shows that humanity has profoundly affected nearly half of the world's oceans, with just a few spots remaining pure.

Pure is a loaded term – after all, humans are part of nature, too. But however one defines the integrity of ecosystems, the bottom line is that humans change the oceans just as much as we change forests or prairies. It's just easier to see the changes when they're not underwater.

Enter a team of researchers led by the National Center for Ecological

Analysis and Synthesis' Benjamin Halpern, who in a study published today in Science used satellite images and custom-made models to evaluate the oceanic impact of coastal development, fishing, fertilizer runoff, shipping traffic and other activities.

Their fine-grained analysis – precise to the square-kilometer scale – showed that just four percent of Earth's oceans are still pristine; coral reefs, seagrass beds, rocky reefs and continental shelves have been particularly hard hit, while soft-bottom shallows and the deep ocean have fared best.

The researchers say their map is just a scaffold for future research:

there are more possible impacts than the 17 measured, and the interconnection and dynamics of aquatic ecosystems are still being explored. But it's still a valuable first step in providing a framework by which the waters on which billions of people rely can be evaluated and managed.

A Global Map of Human Impact on Marine Ecosystems [Science]

Image: Science

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