Clustered parrotfish feeding scars trigger partial coral mortality of massive Porites colonies on the inshore Great Barrier Reef

Abstract

Coral predation by parrotfishes can cause damage to coral colonies, but research into the dynamics of their feeding scars on Indo-Pacific corals is limited. We monitored feeding scars of the parrotfish Chlorurus microrhinos on massive Porites colonies at Orpheus Island (inshore Great Barrier Reef) over 4 months. Of the 30 marks monitored, 11 were single feeding scars, which all healed completely. The remaining 19 feeding marks consisted of clusters of scars. Eight began to recover, while 11 increased in size by 1,576 ± 252 % (mean ± SE). A logistic regression predicted that a single feeding scar on a Porites colony had a 97 % probability of healing; however, where more than three feeding scars were present, this dropped below 50 %. As excavating parrotfishes in the Indo-Pacific often take multiple focused bites, they may have a significant impact on the growth and mortality of massive Porites colonies at Orpheus Island.