During the past half century, the world has lost some 20 percent of its coral reefs. More than half of remaining reefs could be gone in the next few decades due to the impacts of climate change and other human-caused stresses. A recent report published by the World Conservation Union (IUCN) and The Nature Conservancy states that there is still time to avert mass mortality of reefs, if concerted efforts to reduce stresses such as coastal pollution and overfishing are initiated immediately.

A Valuable Resource

Coral reefs cover only 0.2 percent of the ocean floor, but contain roughly 25 percent of global marine species. Coral reefs provide livelihoods to approximately 100 million people, and have an estimated annual net worth of US$30 billion.

But many coral reefs around the world are already severely damaged and in danger of complete collapse due to a combination of human-caused stresses:

Impacts of global warming include:

- Warming ocean temperatures

Corals live within a small range of temperatures. Warming events or other environmental stresses can cause corals to "bleach"--taking on a white color (healthy corals are typically green or brown) due to the expulsion of their symbiotic algae, which are necessary for coral growth.

- Increasing ocean acidity

As carbon dioxide (CO2) levels rise, the ocean becomes more acidic, leading to reduced growth and weakened coral skeletons.

Other stresses on coral reefs include:

- Marine pollution

- Sedimentation and runoff from coastal development

- Harmful fishing and tourism practices

In Coral Reef Resilience and Resistance to Bleaching, the authors state that while the impacts of global warming may be inevitable, reducing other stresses would go a long way toward curbing the declining health of corals and preserving coral reef ecosystems.

Several other stories have recently appeared detailing the devastation of coral reefs:

- In Belize, much of the country's 200 miles of reef have "bleached" in the last decade. Thousands of tourists visit Belize's reefs each year, providing critical income for local residents.

- Researchers have noted that in many places, including the U.S. Virgin Islands, Jamaica and elsewhere in the Caribbean, larger species of coral--essential habitats for many species of fish and other marine species--are being replaced by smaller species due to pollution, warm temperatures, and overfishing.

- At the recently concluded 3rd International Tropical Marine Ecosystems Management Symposium (ITMEMS3, 15-20 October 2006), scientists concluded that sea temperature increase must be limited to 2°C above pre-industrial levels if major damages to tropical ecosystems are to be avoided.

RELATED LINKS:

WRI's Reefs at Risk Project