Coral Reef Fish Communities: Unstable, High‐Diversity Systems?

Abstract

We examined the pattern of development of assemblages of coral reef fishes on artificial reefs at One Tree Reef, Great Barrier Reef. Two sets of 8 reefs were built. To investigate the effects of habitat structure on species diversity, each set consisted of replicate pairs of 4 different reef types: plain (no holes), small-holed, medium-holed, and large-holed reefs. To examine seasonal differences in colonization, I set was established in summer (October 1971) and the other set in winter (July 1972). Visual censuses of the reefs' fish assemblages were made at monthly intervals over 32 mo (summer set) and 23 mo (winter set).We recorded a total of 105 resident species from the artificial reefs. Although less diverse, the fish assemblages differed little in terms of species composition from those of small natural patch reefs. Artificial reefs showed a high between-reef variability in species composition that was largely unrelated to habitat structure. Competitive interactions between species appeared unimportant in explaining the distribution of species between reefs. Likewise, possible positive associations between species were indicated for only a few species.Almost all settlement of the artificial reefs was by juvenile fishes. Recruitment was markedly seasonal and occurred mainly over summer (September-May). Juvenile recruitment patterns showed little year-to-year constancy. Most species tested showed nonrandom, clumped patterns of settlement on replicate reefs. More than half of species tested showed no significant differences in numbers of individuals which settled on different reefs, but the remainder showed significantly greater settlement on some reefs, suggesting habitat selection. For a few species, there was also greater recruitment to reefs already occupied by conspecifics, suggesting possible social facilitation of settlement. For most species, there were no significant interspecific interactions between adults and newly settling juveniles.Between-census variability in species composition was high and species turnover ranged from =17% of species/mo in winter to =39% in summer. Maximum times of persistence for most species were < 12 mo, and for many individuals survivorship was of the order of only a few months. Much of the high turnover appears due to losses through predation.There was no evidence that a persistent species equilibrium was attained during colonization. Because of predation and the seasonally varying, uncertain nature of recruitment, we see the development of any long-term species equilibrium as unlikely. We suggest that nonequilibrium conditions are a characteristic of coral reef fish communities and that because of these conditions, high withinhabitat diversities are maintained.

Algal diversity in relation to physical disturbance: a mosaic of successional stages in a subtidal cobble habitat

“…Evidence from several studies of natural communities supports a non-equilibrium view of community structure (Dayton 1971, 1975, Dayton & Hessler 1972, Abele 1976, Osman 1977, Sale 1977, Strong 1977, Connell 1978, Lubchenco & Menge 1978, Murray & Littler 1978, Talbot et al 1978, Lieberman et al 1979, Sousa 1979a, b, 1980, Ayling 1981, Paine & Levin 1981, McAuliffe 1984. In agreement with these studies, the results presented here suggest that high diversity is maintained in a non-equilibrium state by a balance of processes (disturbance and competition).…”

“…In particular, studies of coral reefs (Connell 1978), coral-associated decapod crustaceans (Abele 1976), rocky intertidal algal communities (Dayton 1975, Lubchenco & Menge 1978, coral reef algal communities (Hay 1981), tropical rain forests (Strong 1977, Connell 1978, marine epifaunal invertebrates (Osman 1977), coral reef fish communities (Sale 1977, Talbot et al 1978, fossils of marine invertebrates on Ordovician cobbles (Wilson 1985), subtidal encrusting communities (Ayling 1981), and algal communities on intertidal boulders (Sousa 1979a), have demonstrated the role of disturbance in influencing local diversity and the development and maintenance of community structure. In these communities where the substratum is potentially limiting, disturbances (processes associ-O Inter-ResearchIPrinted in F. R. Germany ated with partial or total loss of biomass [Grime 19771) create patches of free space that allow a diverse assemblage of organisms to coexist.…”

Community dynamics of tropical reef fishes:local patterns between latitudes

“…This result is consistent with previous studies of pairwise patterns of reef-fish abundance at One Tree Island on both natural and artificial reefs (Sale & Dybdahl 1975, 1978, Talbot et al 1978, Sale & Steel 1989. Similar comparative studies have not been previously done at Lizard Island.…”

Functional role of fouling community on an artificial reef at the northern coast of Rio de Janeiro State, Brazil

“…In the laboratory, the biofouling was identified and quantified by the intersection point technique (Sutherland, 1974). The fouling community was evaluated through its taxonomic composition, relative abundance, structural difference index (Goren, 1979) and turnover rate (Talbot et al, 1978). The two latter reflect quali-quantitative community changes, considering relative species abundance and immigration versus extinction rate on each sampling period.…”