Influence of macroalgal cover on coral colony growth rates on fringing reefs of Discovery Bay, Jamaica: a letter report

This study investigated the hypothesis that alterations in macroalgal cover significantly influenced the growth rates of coral colonies on the fringing reefs of Discovery Bay, Jamaica. For colonies of Montastrea annularis, Porites astreoides, and Sidastrea siderea, radial growth rates were significantly (p<0.02) higher at Dairy Bull (where Diadema antillarum had removed macroalgal cover) than at either M1 or Rio Bueno (where there was c. 80% macroalgal cover). For colonies of Colpophyllia natans and Montastrea fankseii, radial growth rates were significantly (p<0.02) higher at Dairy Bull than at Rio Bueno. It has been suggested that macroalgal shading as well as contact is a significant inhibitor of coral growth, and our results are in accord with that hypothesis. These studies suggest that marine park managers should foster macroalgal predation wherever possible, in order to limit the irreversible decline of coral reefs.