The effects of growth anomaly on susceptibility of Montipora capitata to turf algal overgrowth

Abstract

One of the most prominent coral diseases in Hawai‘i is growth anomaly (GA) of the skeleton. GA reduces key biological functions of Montipora capitata, but the effect of this disease on the ecological competitiveness of the coral has not been investigated. This study evaluated the effect of the GA on the susceptibility of an endemic Hawaiian coral M. capitata to algal overgrowth at Wai‘ōpae, Hawai‘i. Field surveys and photo analyses were conducted to collect epizootiological data. A relationship was found between GA severity and turf algal growth at the colony level; however, this relationship was weaker than expected. Despite the fact that GA lesions can provide areas of protuberant exposed coral skeleton, turf algal overgrowth was no more prevalent on GA-affected colonies than on unaffected colonies. As algal overgrowth is ephemeral compared to the progression of GA, we suggest that filamentous algae takes advantage of ideal environmental conditions regardless of the availability of new surfaces to invade presented by GA lesions.