Occurrence of aggressive mechanisms during interactions between soft corals (Octocorallia : Alcyoniidae) and other corals on the Great Barrier Reef, Australia

Abstract

This study found that on two reefs of the Great Barrier Reef, Australia, most coral colonies within 10 cm of a soft coral colony were interacting to the detriment of one or both colonies. Soft corals were more likely to interact with neighbouring hard corals than with other soft corals. The relative infrequency of ties indicated that two coral colonies were rarely equal competitively. Allelopathy and simple overgrowth were the major aggressive mechanisms of alcyoniids. Soft corals tended to simply overgrow neighbouring hard corals but used allelochemicals more frequently when the neighbour was another soft coral. Other factors influencing the type of aggressive mechanism used included the size of the neighbouring colony. The importance of this to a coral reef community after events such as Acanthaster planci infestations is discussed.