Spatial analysis of intertidal tropical assemblages associated with rocky shores in Venezuela

A quantitative description is made of the intertidal assemblages associated with rocky shores on the coast of Venezuela, considering different hierarchically-structured spatial scales: regions (separated by hundreds of kilometers), locations within regions (separated by tens of kilometers), sites within locations (separated by tens to hundreds of meters) and replicate quadrates (separated by meters). Assemblages of algae varied significantly at all the spatial scales, whereas assemblages of animals varied significantly only at the spatial scales of sites and locations but not at the scale of regions. For the two data matrices (algae and animals), the largest components of variation were found among locations and among replicates, and the smallest were associated with the spatial scale of regions. Findings in this study have relevance for an improved understanding of tropical rocky assemblages because it was shown that, as occurs in other temperate zones, variability at small spatial scales (meters and hundreds of meters) is very important and, consequently, comparisons among places located at larger distances might be confounded by this variability. Moreover, they allow the proposal of conceptual models about ecological processes that might be relevant for these systems.