Scubaism

Coral reefs in the Indian and Pacific Oceans are dying off much quicker than previously thought, a new study shows. For the last two decades, Indo-Pacific reefs have shrunk by 1 percent each year—a loss equivalent to nearly 600 square miles (1,553 square kilometers). That makes the rate of reef loss about twice the rate of tropical rain forest loss.

The study is the first to conduct a regional, long-term assessment of coral reef health in the Indo-Pacific region, which is home to 75 percent of the world’s coral reefs and the greatest diversity of coral and fish.

Researchers compiled more than 6,000 underwater surveys, which were conducted between 1968 and 2004, in ten subregions of the Indo-Pacific. These included Indonesia, the Philippines, and Australia’s Great Barrier Reef.

Each survey measured the percentage of seafloor covered of hard corals—a key indicator of reef health.

Marine ecologists from the University of North Carolina found that hard-coral cover on Indo-Pacific reefs currently averages 22 percent of the seafloor —a much lower figure than expected. The percentage is also surprisingly consistent across the region.

The widespread declines may be due to regional or global stressors such as increased sea temperatures, which trigger coral bleaching, said the researchers.