Outbreaks of a coral-eating starfish have occurred in Fiji resulting from overexploitation of the predatory fishes that normally limit its numbers. The impacts of the starfish are dramatic, with previously pristine coral reefs being turned into dull algal mats. Worryingly, Dulvy, Freckleton and Polunin - the authors of a study in the May issue of Ecology Letters -- found that light levels of exploitation by subsistence islanders fishing just for food for themselves and their families could cause such profound changes. Exploitation of the seas has resulted in a worldwide decline in predators. However, surprisingly little is known of the biodiversity impact of removing marine predators.
It was previously thought that diverse ecosystems such as coral reefs would be relatively resilient to the low levels of predator removal - this study suggests this may not be so. Maintaining high predator abundances across reefs will reduce the risk of starfish outbreaks.