A recent paper by Paddack et al in Current Biology (doi:10.1016/j.cub.2009.02.041) that shows that observed declines in fish populations in the Caribbean are consistent across all subregions of the Caribbean basin (2.7% to 6.0% loss per year) and appear to be linked to coral reef collapse. In Science Jackie Grom reports on the paper in Reef Fish Threatened by Coral Loss:
Ecologist Michelle Paddack, a postdoctoral student at Simon Fraser University in Burnaby, Canada, teamed up with an international group of scientists to find out. They analyzed data from 48 studies, including peer-reviewed papers, government and university research reports, and unpublished data sets, that covered trends on 318 Caribbean coral reefs and 273 species of reef fish over a 53-year period. Today in Current Biology, the team reports that reef fish populations were relatively constant from 1955 through 1995 but then plunged by about 3% to 6% each year through 2007. The declines occurred in three of six dietary groups, including those that fed primarily on algae, invertebrates, or a combination of fish and invertebrates. The loss of algae-eating fish, such as parrotfish and surgeonfish, is worrying, says Paddack, because they help the reefs thrive by clearing away algae.
The declines don’t appear to be caused by overfishing, because the losses were similar for fished and nonfished species. Paddack says that doesn’t mean fishing doesn’t have an impact but that something even bigger is influencing the entire sea. The researchers suggest that the culprit is unprecedented loss of coral reefs over the past 3 decades. Even though the reduction in fish populations lags nearly 20 years behind the coral loss, the consistency in fish declines across a wide range of species points to the loss of coral as the cause, they say.
“We’ve known that corals are declining and fish are declining, but boy, I think it’s powerful just to see the patterns at the regional scale,” says marine ecologist John Bruno of the University of North Carolina, Chapel Hill. Biologist Richard Aronson of the Florida Institute of Technology in Melbourne says that the suggestion that coral reef loss is behind the declines in reef fish is intriguing. But to nail down the link, he’s hoping to see studies that relate fish declines to the time it takes for the reefs to structurally deteriorate after they die. “I liked this paper a lot; it got me excited [about coral reefs] all over again,” he says.