Fish help coral reefs recover

Can fish save coral reefs from dying? It seems so, if one is to go by an instance where the fish did help coral reefs recover from cyclones and predators.

Worldwide, these valuable marine systems are being increasingly disturbed by environmental events that are causing their decline, yet some coral reefs recover.

University of California-Santa Barbara (UCSB) researchers have discovered that the coral reefs in the South Pacific island of Moorea, French Polynesia, may be healthy due to protection by parrotfish and surgeonfish that eat algae.

In the case of the Caribbean, reefs that suffer large losses of live coral often become overgrown with algae and never return to a state where the reefs are again largely covered by live coral, the journal Public Library of Science reports.

Conversely, the reefs surrounding Moorea experienced large losses of live coral in the past -- most recently in the early 1980's -- and have returned each time to a system dominated by healthy, live corals, according to a California statement.

"We wanted to know why Moorea's reefs seem to act differently than other reefs," said Tom Adam, first author, postdoctoral fellow at UCSB's Marine Science Institute.

"Specifically, we wanted to know what ecological factors might be responsible for the dramatic patterns of recovery observed in Moorea," Adam added.

The research team was surprised by its findings. The biomass of herbivores on the reef -- fish and other animals that eat plants like algae -- increased dramatically following the loss of live coral.

"What was surprising to us was that the numbers of these species also increased dramatically," said Andrew Brooks, co-author, associate project scientist with Marine Science Institute.

"We were not simply seeing a case of bigger, fatter fishes -- we were seeing many more parrotfishes and surgeonfishes, all of whom happened to be bigger and fatter. We wanted to know where these new fishes were coming from," Brooks added.