SPATIAL PATTERNS IN BENTHIC INVERTEBRATE COMMUNITY STRUCTURE - PRODUCTS OF HABITAT STABILITY OR ARE THEY HABITAT SPECIFIC

1. The effects of habitat stability on benthic invertebrate community structure were examined at eleven sites (ten streams and a wind-swept lake shore) with similar physicochemical characteristics but differing stability. 2. Habitat characteristics were assessed to place the study sites within the framework of the disturbance-productivity-diversity model, the intermediate disturbance hypothesis and a variant of the habitat templet model to examine their predictions with respect to community structure. 3. Many of the most common invertebrate species were present at all the study sites, although their relative abundance and density differed markedly between sites. Thus, while stability did not appear to affect colonization of the study sites by these taxa, it did affect their relative success. 4. Communities at unstable sites were very similar and shared a number of taxa such as Deleatidium, Austrosimulium and several species of chironomid, presumably well-adapted to surviving and recolonizing after flood events. 5. Communities at the stable sites differed markedly, both from each other and the group of unstable sites. The characteristic fauna at each of the stable sites seemed to be a result of the site's intrinsic character and possibly biotic interactions. 6. Although stability was a pervading influence on community structure, acting as a bottleneck to the development of a site-specific suite of taxa, none of the above models could adequately explain the observed patterns.