'Stability' of the fouling communities on the pilings of two piers in South Australia.

The subtidal communities of sessile organisms on the pilings of two piers were observed by photography of fixed quadrats over a period of two years. Data are presented on species-composition, relative abundance of species, and maximum longevities of individuals and colonies. The fluctuations in various properties of the communities (e.g. measures of species diversity, and percentage vovers of species and phyletic groups) are tested by a priori defined criteria for "narrow stochastic boundedness" and most are found to be narrowly bounded, despite considerable turnover of space. We conclude that most properties of the community vary less through time-that is, the community is in a sense more "stable"-than fouling communities previously studied using small plates immersed for relatively short periods. Long-lived species are relatively more abundant on the pilings than in plate-studies. These differences are attributed to the large size and long period of submersion of the pilings. Our results appear similar to those of other studies on large, old substrata.