In the most comprehensive study yet of Caribbean coral reefs, scientists have discovered that the 50 to 60 percent coral cover present in the 1970s has plummeted to less than 10 percent.
“I’m sad to tell you it’s a dire picture,” Carl Gustaf Lundin, director of IUCN’s Global Marine and Polar Programme, said at a news briefing last Friday at the World Conservation Congress in Jeju Island, South Korea.
Much of the decline is caused by a massive die-off of sea urchins in the 1970s—possibly due to disease. Without these reef grazers—the “cows in the field” that keep vegetation in check—the number of algae and grasses have skyrocketed, dominating reefs and pushing corals aside, Lundin said.
What’s more, overfishing of grazer species such as parrotfish or surgeonfish is allowing more algae to take over and outcompete the coral, said Ameer Abdulla, IUCN senior advisor on Marine Biodiversity and Conservation Science.
The scientists also said that climate change played a role. The warmer waters—often caused by hurricanes blowing through—have harmed reefs. When the water gets too hot, algae that live inside coral, called zooxanthellae—abandon their hosts, causing the coral themselves to bleach and eventually die.
“For those that are very skeptical of what’s happening with climate change, I would say reality is not in their favor.”
Corals are vital for many reasons, from boosting tourism dollars to local communities and even buffeting islands themselves from powerful storm surges, Lundin said.
The good news is that there are ways to protect the remaining 10 percent of Caribbean corals.
For instance, putting in place marine protected areas can reduce the pressure of overfishing. Governments can also work with local fishers to maintain their livelihoods, for instance by raising the value of individual fish so that the fishers catch fewer animals.
The bottom line, Abdulla said, is that “the Caribbean system is one of first systems to experience collapse—it’s something that will happen across the globe if human use of coral reefs continues as it is.”