Recovery of a coral reef keystone predator, Balistapus undulatus, in East African marine parks

The red-lined triggerfish (Balistapus undulatus) is a major predator of sea urchins and the loss of this species, along with other less influential se a urchin predators, has resulted in the proliferation of sea urchin populat ions on the coral reefs of East Africa. I studied the recovery of B. undula tus and the associated demise in their sea urchin prey in five Marine Prote cted Areas (MPAs) which differed in their age, such that the data collected spanned a 30-year range in the age of protection. Results suggest that pre dation on sea urchins and B. undulatus dominance recovered on a time scale of 5-10 years, but sea urchin populations were not reduced below 1000 kg/ha for more than 10 years, and B. undulatus populations may require > 30 year s to recover. In a new MPA, B. undulatus competitively excluded a subordina te wrasse predator, Cheilinus trilobatus, at baited sites in < 8 years. A s econd triggerfish, Balistoides veridescens, was the competitive dominant to B. undulatus in direct interference interactions, but B. viridescens was n ot found in 2.7 ha of sampling and rarely seen eating sea urchins at baited sites. An even longer estimate of top predator recovery would occur if B. viridescens is the dominant sea urchin predator. This study suggests that s hort and temporary closures of < 10 years will not fully restore reef ecolo gy, and that fully protected and permanent MPAs are a necessary part of cor al reef conservation programs. (C) 2000 Elsevier Science Ltd. All rights re served.