Temps de lecture :2 minutes
If awards were given to nature’s greatest masterpieces, coral reefs would surely be a prizewinner. These ecosystems display a staggering degree of biodiversity: they are home to more than 93,000 recorded species, or 33% of all marine species—species whose variety of forms and colours is unequalled anywhere on the planet. And yet the area covered by coral reefs represents only 0.02% of the surface area of the world’s oceans.
Corals are extremely fragile organisms. The product of a complex relation between single-cell algae and colonies of small fixed organisms known as polyps, they are vulnerable to the slightest changes in their environment. Human coastal populations are getting ever bigger, and the quantity of waste products (domestic, agricultural, and industrial) ending up in the sea is rapidly increasing. The ocean, too, is becoming warmer, and also more acid as a consequence of our CO2 emissions, threatening the growth of coral. And, finally, coral reefs—mainly situated in developing countries—are coming under increasing pressure from fishing, particularly illegal and destructive practices that include the use of explosives and cyanide poisoning. What’s more, there is nothing marginal about these practices: they are said to be affecting 80% of all corals, and more than 1,000 tons of cyanide has been used in the Philippines alone.
The result is that 27% of all coral reefs have vanished and another 30% are at risk. And yet these marine ecosystems are valuable to mankind in a number of ways. Their potential as a food source is enormous: a single square mile of coral, if well managed, can produce an estimated 375 tons of fish a year. Coral reefs are also a major tourist attraction: Australia’s Great Barrier Reef generates 1 billion dollars of income a year. And coral reefs protect our shores from costly damage wreaked by storms and hurricanes.
All of this more than justifies the protective measures required to save coral reefs, including—as a matter of urgency—the construction of filtering plants, changes to farming methods in coastal regions, and the regulation of fishing and tourism. Corals are adapted to stable tropical conditions and are highly sensitive to changes in temperature: steps to halt global warming are therefore another urgent priority.