Normal coral growth rates on dying reefs: Are coral growth rates good indicators of reef health?

Massive coral growth rates may be poor indicators of coral reef health wher e coral reefs are subject to combined eutrophication and sedimentation. Mas sive coral growth (vertical extension) rates on polluted reefs were not dif ferent from extension rates on unpolluted reefs, while live coral cover was low and bioerosion intensity high, leading to net reef erosion and death o f the polluted reefs. These combined patterns of coral growth rates, coral cover and bioerosion were documented on reefs affected by land-based pollut ion in the Java Sea, South Sulawesi and Ambon, Indonesia. Acid-insoluble co ntent in coral skeletons reflected land-based pollution stress on reefs mor e reliably than did coral extension rates. Coral skeletal density was lower on polluted Ja, a Sea reefs than on unpolluted reefs used as reference sit es, but coral calcification rates,were not significantly different. The mos t eutrophied Java Sea reefs had net carbonate loss, indicating net reef ero sion, while a fringing reef adjacent to mangroves and two unpolluted coral cays both had positive net carbonate production, Coral growth and reef grow th were decoupled, in that coral growth rates did not reliably predict rate s of reef accretion. The apparently paradoxical combination of normal to ra pid coral growth and net reef erosion on polluted reefs illustrates the nee d for a whole-reef perspective on coral reef health. (C) 2000 Elsevier Scie nce Ltd. All rights reserved.