Spatial scale drives diversity patterns of benthic macroinvertebrate communities in tropical estuaries.

Identifying the hierarchical spatial levels that show the greatest dissimilarities between communities and how these patterns are generated is essential to provide insights into the monitoring and protection of biodiversity. In this study, we additively partitioned diversity of macroinvertebrates into alpha, beta, and gamma diversity across multiple scales in typical and semi-arid tropical estuaries. We also determined which components of the total beta diversity, in terms of species replacement or richness difference (presence-absence data) and abundance difference (relative abundance data), had the greatest relative importance in structuring the composition of benthic macrofauna. In typical and semi-arid tropical estuaries, a non-random spatial pattern was observed in additive partitioning of diversity, with higher values of beta diversity obtained at the largest scales analyzed. When considering the presence-absence data, in general there was no clear trend which components of beta diversity had greater relative importance in typical estuaries. In the semi-arid tropical estuaries, the richness difference component showed greater relative importance in the rainy season, whereas the species replacement presented greater proportions in the dry season. When considering abundance data, in general the abundance difference component showed greater relative importance in typical and semi-arid tropical estuaries in the two seasonal periods. Therefore, approaches based on the presence/absence and on the relative abundance of species provided complementary answers about the distribution patterns of benthic macroinvertebrate communities. We demonstrated that environmental filtering and dispersal limitation may affect the patterns of distribution of benthic macrofauna in estuaries located in regions with different climatic conditions. [ABSTRACT FROM AUTHOR]