Fish in the Caribbean have declined significantly since 1995, suggesting that 30 years of steady coral loss in the region is taking its toll, new research shows.

The overall density of fish in the Caribbean thinned an average of 5 percent annually between 1996 and 2007, according to a study published in today's Current Biology. The findings are based on an analysis of 48 previous studies over half a century and included 273 fish species.

We noted last month that the world's coral is dying at record rates because of pollution, disease and global warming. In the Caribbean, 80 percent of coral has died over the past three decades, at a rate of about 8 percent a year, says study co-author Michelle Paddack, a post-doc in biological sciences at Simon Fraser University in Canada. But the effect on fish there has only become apparent in the last dozen years.

"There might be a lag in the impact," Paddack tells ScientificAmerican.com. "It may be that when the corals first die, their structures are still intact and the fish can [still] use it as refuge and can eat on it." But, she says, if those corals aren’t replaced and are eroded by waves, sea urchins and sponges, their structure becomes less complex, reducing the number of places young fish can hide and find food.

Some fish are especially affected: herbivores such as parrot fish and surgeons, invertivores such as butterfly fish, and carnivores like grunt. Overfishing is responsible for some of the loss of species in the Caribbean, but "as their habitat is degrading, it's affecting all fish, whether they're fished or not," Paddack says.

"These fish are more vulnerable to this loss of coral cover than we thought," she adds. "It emphasizes that reef structure is quite important."

Surgeon fish by Clinton and Charles Robertson via Wikimedia Commons