Coexistence of coral reef fishes ? a lottery for living space

It is argued that reef fishes are preadapted for forming inter-specific lotteries for living space if several species with similar requirements occur together, and may explain the typically high within-site diversity found in them.

Abstract

Data are summarised from studies of two reef fish communities — pomacentrids territorial on rubble patches, and fishes resident in small isolated colonies of coral. In each case there is evidence that availability of living sites limits numbers of fishes, and that similar species of fish use the same kinds of spaces. Priority of arrival as recruits, rather than subtle differences in requirements or competitive abilities of adults, appears to determine which species holds each site. Faced with a limited and patchy supply of living space, most reef fishes are sedentary as adults, and produce frequent clutches of pelagic larvae over extended breeding seasons In this way they maximise their chances of getting offspring into suitable living sites as such sites appear. It is argued that by adopting this strategy, reef fishes are preadapted for forming inter-specific lotteries for living space if several species with similar requirements occur together. Such lotteries among similar species may be a feature common to many reef fish communities, and may explain the typically high within-site diversity found in them.