Anthozoan dominated benthic environments

Abstract

The coral reef ecosystem exists and persists only in virtually fully saline water of a particular temperature range, at shallow depths, where the substratum is firm. This is a consequence of the rather narrow physico-chemical tolerances of hermatypic scleractinian corals, the animals that are the main builders of reef framework. Commonly, they are also major occupiers of space in such habitats. However, in other shallow, tropical marine environments, or in the same habitats under different conditions, non-scleractinian anthozoans -- typically zoanthids and octocorals -- occupy comparable expanses of substratum. Likewise, some temperate and deep-water marine communities are dominated by anthozoans, generally actinians. Although these animals do not structure their communities physically, they are, in many respects, functionally comparable to reef-building corals. Thus, such anthozoans appear to comprise a group of ecologically equivalent (which is not to say interchangeable) benthic dominants, the distribution of which is determined mainly by physico-chemical factors, mediated and modulated -- especially on a local scale -- by biotic ones.