Damage and regeneration: links to growth in the reef-building coral Montastrea annularis

Abstract

The influence of colony tissue regeneration on growth was studied in the reef-building coral Montastrea annularis (Ellis & Solander, 1786) by buoyant weighing. Experimental corals consisted of a series of cores, 2 cores from each of 20 colonies. One core of each pair was artificially damaged by removing approximately 1 cm2 of tissue and skeleton, the other served as a control for normal growth. Growth was measured as calcification, i.e. mg calcium carbonate production. There was a linear relation between growth and solar radiation. Variation in growth, calculated before the regeneration experiment, was insignificant between cores from the same colony but significantly different between colonies. Growth was reduced in damaged cores when compared to controls. Calcification decreased immediately upon damage and remained reduced during the whole study (56 d). Lesions caused by physical damage did not always close completely. We propose and test a model that describes regeneration in terms of closure of lesions. Thls model includes an asymptote in an exponentially decreasing function. Calcification remained suppressed after regeneration slowed down and lesions were still not completely closed, probably because of the formation of polyps and skeletal features in the new tissue. We suggest regeneration to be fuelled by polyps and tissue directly bordeling the damaged area. Also, successful regeneration depends on the amount of tissue bordering a lesion and not on colony size.