A conceptual framework to study the effects of habitat structure on diversity of benthic assemblages

Background/Question/Methods Understanding responses of assemblages to modification or destruction of coastal habitats is limited by our knowledge about how attributes of habitat influence the diversity and abundances of organisms. Habitat structure is usually defined specifically for each habitat, compromising comparisons of different habitats. Several conceptual models are proposed to explain the variability of assemblages due to differences in structure of habitats. For example, habitat may differ in: amount of structure (e.g. patch-size, number of structural components); composition (e.g. diversity, relative abundances and identity of structural components); and connectivity between patches of the same habitat or adjacent habitats. Predictions from these models were tested using assemblages of intertidal invertebrates colonizing patches of habitat constructed of different types, numbers and of components in different experimental combinations. Results/Conclusions In homogeneous patches, patch-size and identity of components of habitat showed non-interactive effects on the structure of assemblages. In contrast, benthic assemblages were affected by an interaction between number, relative abundance and identity of heterogeneous patches. These results emphasize the importance of recognizing effects of different attributes of habitat so that we can unravel processes influencing patterns of diversity and distribution of benthic assemblages.