Human activities have affected approximately 40 percent of the world's oceans, leaving only about 4 percent relatively pristine, a new study funded by the David and Lucile Packard Foundation, the National Center for Ecological Analysis and Synthesis, and the National Science Foundation finds.
Recently published in the peer-reviewed journal Science, the study documents how human activities and by-products such as fishing, fertilizer runoff, commercial shipping, and pollution have affected marine ecosystems, continental shelves, and the deep ocean. The study's findings have been incorporated in a first-of-its-kind, high-resolution, global map reflecting seventeen types of impact on marine ecosystems. The conclusion: No areas of the ocean are completely untouched by human activities, and roughly one-third of all ocean areas have been heavily impacted.
According to lead author Benjamin Halpern, previous studies have tended to focus on how a single type of human activity or the condition of one marine ecosystem affects the ocean. Halpern's study, in contrast, examines many different types of human activities and all marine ecosystems simultaneously, presenting a more thorough, global picture of the oceans' health.
Ocean areas most affected by human impact include the North Sea, the South and East China Seas, the Caribbean Sea, the Atlantic Ocean along the east coast of North America, the Mediterranean Sea, the Red Sea, the Persian Gulf, the Bering Sea, and parts of the western Pacific. Damage includes reductions in fish and sea animals as well as problems for coral reefs, seagrass beds, mangroves, rocky reefs and shelves, and seamounts. The areas least affected by human activities are concentrated near the poles, although those areas increasingly are being affected by climate change.
Despite the challenges identified by the study, Halpern said there was reason to hope. "With targeted efforts to protect the chunks of ocean that remain pristine," he added, "we have a good chance of preserving these areas in good condition."