Although they occupy less than one quarter of 1 percent of the marine environment, coral reefs are home to more than a quarter of all known marine fish species.[1] These habitats have been called the rainforests of the marine world: highly productive, rich in species, and -- because they predominate in many regions noted for extreme poverty and high population growth rates -- particularly vulnerable to future degradation.

Seventy percent of the planet is covered by oceans, yet humans have barely begun to catalog the biota found within marine environments. Over recent decades, scientists, policy-makers, and the public have become increasingly aware of the magnitude of destruction of terrestrial habitats, especially the biologically rich tropical rainforests, and the need to stem the onslaught of human pressures on remaining natural places. Knowledge has proved key to raising awareness: by at least roughly gauging -- through such figures as deforestation rates and estimates of species loss -- the extent and magnitude of human impact on terrestrial biodiversity, scientists have demonstrated what is at stake should poorly planned development continue unchecked.

Midway through the 1998 "Year of the Ocean" and following the 1997 "Year of the Reef" -- two campaigns aimed at raising global awareness of the importance of our marine heritage -- we still lack comprehensive estimates regarding the status of, and the magnitude of threats to, these aquatic ecosystems. In terms of addressing knowledge gaps, coral reefs are a priority because of their extraordinarily high biological richness and the multitude of products and ecosystem services they provide to human beings.

This report presents a detailed, map-based analysis of threats to (and pressures on) the world's coral reefs. Until now the only information on the status of coral reefs worldwide was an estimate, first published in 1993, which indicated that 10 percent of the world's reefs were dead, and that 30 percent were likely to die within 10 to 20 years.[2]

These figures, which have since been widely quoted, were based on guesswork by a number of scientists and on anecdotal evidence. Reefs at Risk -- the first systematic and data-driven global assessment of these habitats -- confirms that coral reefs are seriously threatened in most parts of the world. The maps in this report provide a detailed picture of where reefs are in jeopardy, identify reefs at risk that are of high biodiversity value, and show where reefs lack protection through parks, sanctuaries, and reserves.

Our results serve as an indicator of the threats to these ecosystems, not as an actual measure of degradation. Scientists do not know the actual condition of the vast majority of the world's reefs. In the Pacific, for example, 90 percent of the coral reefs have never been assessed.[3] In the absence of complete information on reef condition, we have drawn together available global maps and other data sets that measure human activity and, using a geographic information system and more than 800 mapped ReefBase sites[4] known to be degraded by humans, have modeled areas where one might predict degradation to occur, given existing anthropogenic pressures on the land- and seascape. Reefs at Risk draws on 14 distinct data sets and the input of coral reef experts and scientists from around the world.

Notes

1. Don McAllister, "Status of the World Ocean and Its Biodiversity," Sea Wind 9, no. 4 (1995), 14.

2. Clive Wilkinson, "Coral Reefs Are Facing Widespread Devastation: Can We Prevent This Through Sustainable Management Practices?" in Proceedings of the 7th International Coral Reef Symposium 1 (Guam, 1993), 11-21.

3. Elizabeth Pennisi, "Brighter Prospects for the World's Coral Reefs?" Science 277 (July 25, 1997), 492.

4. ReefBase -- a database produced by the International Center for Living Aquatic Resources Management -- is the most comprehensive source of global information available on coral reefs.