ABSTRACT

Figure 4 summarizes the physical and ecological interactions important in structuring reef benthic communities. Temperature is clearly important in limiting tropical hermatypic coral species. Although experimental evidence comes from only a few sites, it does appear that seaweeds compete with corals and observational evidence on various scales in both temperate and tropical regions suggests that exclusion of corals can result. Controlled experimental studies are needed from more sites. Similar factors, namely variation in grazing and nutrient regimes appear to be influential in determining benthic community structure along gradients both within and between latitudes. Controlled experiments on nutrient and sedimentation effects at both high and low latitudes are needed, especially to distinguish the relative importance of their many plausible mechanisms of impact (e.g. by alteration of light or turbidity, bioerosion, recruitment inhibition, etc). Most studies to date have examined factors regulating coral or algal components of the community; rarely have both coral and algal components of the benthos been examined together, nor have multiple factors been manipulated simultaneously to begin to discern the complicated interactions of these factors (with each other and with natural disturbances such as storms or El Niño events) that most likely operate in natural coral reefs.