JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecological Monographs.Abstract. Community development was followed for 21/2 to 31/2 years on unglazed ceramic tile plates (232 cm2), suspended horizontally beneath the Duke University Marine Laboratory dock, in Beaufort, North Carolina. Series of 3 or 4 plates were submerged at approximately the 1st of each month from May-November 1971 and from April-November 1972. Percentage cover for each species that settled and grew on the lower surface was estimated at 6-to 8-week intervals, using 75 points randomly positioned over the plate area. Samples were nondestructive; plates were resubmerged after each census. Larval recruitment was estimated at 1to 3-week intervals on newly submerged plates. Temperature and salinity were also measured.Initial community development was relatively unpredictable. Larval recruitment patterns varied markedly from year to year and as a result, different patterns of initial community development were observed both within and between years. Instead of preparing the way for subsequent arrivals, most resident adults strongly inhibited the recruitment and growth of other species. Species varied in their ability to resist subsequent invasion as adults and in their ability to invade occupied substrate as larvae. After an unpredictable initial developmental phase, subsequent changes in species composition depended in part on the degree to which larvae were able to invade existing adult assemblages. This in turn depended on the identity of the resident adults and the identity of the invading larvae. As a result, the direction and rate of community development, dependent on the order of initial invasion and subsequent recruitment, were difficult to predict although an equilibrium number of 8-10 species/plate was often observed. Adult residence time was generally < 1 year and the mortality and/or disappearance of these adults produced 20-60Wo free space on an approximately annual basis. This free space was usually occupied by recruits of a different species than the original occupant. The combined addition of species through larval recruitment and subtraction of species as a result of adult mortality produced dramatic changes in community structure each year. There is no reason to believe these changes will ever cease. We conclude that succession in the classical sense (Odum 1969) does not occur in this system because initial development was variable, residents impeded subsequent development instead of enhancing it, and there was no stable climax.There is good reason to believe similar processes occur in other temperate and subtropical fouling communities. We believe...

Distributions of numerical abundance and resource use among species are fundamental aspects of community structure. Here we characterize these patterns for tropical reef fishes and corals across a 10,000-kilometer biodiversity gradient. Numerical abundance and resource-use distributions have similar shapes, but they emerge at markedly different scales. These results are consistent with a controversial null hypothesis regarding community structure, according to which abundance distributions arise from the interplay of multiple stochastic environmental and demographic factors. Our findings underscore the importance of robust conservation strategies that are appropriately scaled to the broad suite of environmental processes that help sustain biodiversity.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. Species richness in ecological communities has traditionally been explained in terms of species interactions, especially competition, operating within the local community over relatively short periods of time. 2. Recently, it has become clear that ecological communities can be organized by a variety of processes operating at different spatial and temporal scales. 3. Since local communities are imbedded within larger geographic regions, regional/ historical phenomena and local processes may influence local richness jointly and should be analysed simultaneously. 4. Here we perform such an analysis by comparing assemblages of hermatypic scleractinian corals from different regions sampled at over 100 sites around the world. 5. Using multiple regression analysis, we find that local richness is as sensitive to regional richness as it is to each of two variables (depth and habitat) that subsume much of the local variability at a site. 6. Our results indicate that although coral assemblages are believed to be intensely interactive, they are, nevertheless, regionally enriched and show no evidence of saturation. 7. Multi-scale effects on local richness demand further investigation to clarify causal relationships, and to enlighten policy decisions over issues of biodiversity, habitat loss and fragmentation, and ecological restoration.