for National Geographic News
The return of a top predator in a Bahamas marine reserve is proving unexpectedly beneficial to coral reefs there, according to a new study.
The finding is a relief to scientists, who were concerned that the reserve's population of predatory Nassau grouper would swell at the expense of the already vulnerable reefs, which are quickly disappearing due to disease, hurricanes, and warming oceans.
"Actually there really is no cause for concern," said Peter Mumby, a marine biologist at the University of Exeter in England and lead author of the study.
Mumby and his colleagues conducted the study in the Bahamas' Exuma Cays Land and Sea Park, which was established in 1959 and closed to fishing in 1986.
They found that while the reserve has allowed Nassau grouper to flourish, large species of parrotfish have thrived as well.
This discovery surprised scientists, because parrotfish are prey for the Nassau grouper.
Parrotfish are also crucial to the health of coral reefs, because they are one of the few creatures that graze on seaweed. Left uneaten, the seaweed suffocates the corals and prevents reef growth.
The research is reported in tomorrow's issue of the journal Science.
Mumby's team feared that larger numbers of grouper in the reserve would cause the parrotfish population there to crash, to the detriment of the reef.
"The reserves are working very well for the predators," said Dan Brumbaugh, a senior conservation scientist with the American Museum of Natural History in New York and a study co-author.
In fact the researchers found twice as many parrotfish predatorsmostly Nassau grouperinside the park as they did outside it.
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