Interspecific aggression among stony corals in Eilat, Red Sea: A hierarchy of aggression ability and related parameters

Stony corals use various aggressive mechanisms to compete for space, which is often considered a limiting resource on coral reefs, particularly at undisturbed sites. Interspecific aggression among stony corals has been studied in Eilat [Northern Gulf of Aqaba (Eilat)], using random SCUBA traverses and line transects. The resultant hierarchy, constructed by ranking the abilities of species to damage neighboring corals, reveals intransitive interactions which occur mostly within the intermediately-aggressive species. Possible relations of the aggression rank of the species studied to ecological or biological parameters (i.e., polyp (calyx) size, and species abundance and distribution) were examined. No apparent correlation was found between aggression and species abundance. Other parameters (i.e., polyp size and species distribution) show significant links with the species' aggression rank. Aggression hierarchies are among the ecological parameters used to compare coral reefs of different geographical regions. The present paper provides a first record of the aggression hierarchy for Red Sea corals, which may be compared to hierarchies from other regions. The constructed aggression hierarchy may serve as a step towards a better understanding of the ecology of coral reefs in the Gulf of Aqaba.