Coral Crisis

Craig Dahlgren

Some reefs in the Caribbean are on the verge of complete collapse thanks to impacts that include overfishing, pollution, agricultural runoff, ocean acidification and global warming. A new report from the International Union for Conservation of Nature (IUCN) finds that there is just 8% of live coral cover on Caribbean reefs on average, compared to more than 50% in the 1970s. With some of the most beautiful and biologically diverse ecosystems anywhere on earth, coral reefs across the Caribbean are a major tourism draw, and hugely important for their support of coastal livelihoods and seafood-based diets. Around the world, coral reefs hold up to a quarter of all marine species and are rightfully known as the rainforests of the sea for their concentrated biodiversity.“Looking forward, there is an urgent need to immediately and drastically reduce all human impacts if coral reefs and the vitally important fisheries that depend on them are to survive in the decades to come,” says Carl Gustaf Lundin, Director of IUCN’s Global Marine and Polar Program.

Warming waters caused by global warming have led to massive coral bleaching events across Caribbean reefs in past years, including 1998, 2005 and 2010 ((). Bleaching occurs when corals are under stress—often by rising water temperatures—and expel the algae that are living symbiotically within them; without the algae, corals lose their brilliant hues and may never generate new life.

Not all Caribbean corals are in such dire straits—according to the IUCN report, “many reefs in the Netherlands, Antilles and Cayman Islands still have 30% or more live coral cover, little microalgae, and a moderate (albeit strongly depleted) abundance of fish.” But in Jamaica and the U.S. Virgin Isalnds, live coral cover is well below 10% with other indications of reefs in poor health, including lots of microalgae and “virtually no fish larger than a few centimeters.”

The report notes that it’s not entirely clear why there are such discrepancies between reefs, although reef management is certainly a factor—including fishing regulations—as well as the number of hurricanes and degree of coral bleaching and disease.

The IUCN assumed leadership of the Global Coral Reef Monitoring Network in 2010 and is in the process of documenting reef decline across the world with a worldwide overview expected by 2016. By establishing a baseline and examining reef differences, the network hopes to gain essential knowledge in how to preserve and restore coral reefs into the future.