Interspecific Aggression Between Reef Corals with Reference to Their Distribution

Abstract

About 700 observations were made of interspecific aggression between coral species on reefs of Chagos, Indian Ocean. From informat~on on which species killed, or were killed by, others a rough hierarchy of coral dominance was made in which the commonest 54 species were categorised as aggressive, intermediate or subordinate. The degree of aggression shown by a species bears little apparent relationship to its morphology or taxonomic position, and most sub-orders and families considered contained species havlng a wide range of aggressive behaviour Corals that were most aggressive include the freeliving fungiids, Galaxea clavus, Acropora palifera, A. hyacinthus and Goniopora spp.; the least aggressive were Porites sp. and Seriatopora hystrjx. Interspecific aggression is tentatively related to coral zonation, and it is shown that the most aggressive species are those that often form clearly defined, nearly mono-specific zones. The possible contribution of aggression to coral zonation is discussed and compared with the situation in the Atlantic Ocean where aggressive corals are, by contrast, more minor components of the reef.