Coral reefs under threat.

• Author: McKeown, Alice
• Position: VITAL SIGNS

About one-fifth of the world's coral reefs have already been lost or severely damaged, while another 35 percent could be lost within 10-40 years, according to the latest review by the Global Coral Reef Monitoring Network. The number of coral reefs considered at low risk stood at 46 percent, up from' 30 percent only four years ago, but the number of effectively lost reefs remained constant during the period--although this figure was double the 10 percent lost or severely damaged in the first global estimate in 1992. However, the recent estimates do not take into account risks from climate change; when these are included, all coral reefs are in danger and widespread mortality is predicted.

Coral reefs in Asia and the Indian Ocean are most at risk, with 54 percent either lost or critically threatened and another 25 percent moderately threatened. Southeast Asia, which contains the highest biodiversity of all coral reefs as well some of the world's highest human population densities, has already lost 40 percent of its reefs (36,680 square kilometers).

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In the Caribbean region, 38 percent of coral reefs are either lost or critically threatened and 24 percent are moderately threatened. The Middle East region contains one of the areas with the lowest-risk reefs (in the Red Sea), as well as the area with the largest percentage of lost reefs, the Persian Gulf, Arabian Sea, and Gulf of Oman.

Coral reefs in the Pacific Ocean are by far in the best shape, with only 11 percent lost or critically threatened, 16 percent moderately threatened, and 72 percent considered at low risk.

There are roughly 284,000 square kilometers of coral reefs in the world, covering less than 0.1 percent of the world's oceans--equal to about 0.6 percent of the world's agricultural lands. But, though relatively rare, coral reefs support more than a quarter of all known fish species and more species per unit area than any other ecosystem. Coral reefs directly supply about 2-5 percent of the global fisheries harvest and are an important protein and income source, especially in developing countries. They provide resources and food for about 500 million people across the globe, including 30 million people who are almost completely dependent on reefs and associated coral resources. The associated goods and services are worth an estimated US$30 billion per year.

Many of the ongoing threats...