Patterns of diversity in marine Gastrotricha from Southeastern Brazilian Coast is predicted by sediment textures

Broad spatial variations of biodiversity are associated with patterns and processes at different scales, and are well known for large terrestrial animals. For the interstitial microscopic fauna a wide distribution conception is accepted for several phyla. This assumption is being revised since more information has become available on their biogeography and general macroecological threats. This study analyzed the variability of marine Gastrotricha diversity among benthic habitats and localities along the Brazilian coast. We tested the hypothesis that sediment textures, location, tidal zones, and their interactions, are potential explanatory variables that affect the Gastrotricha diversity. Richness estimates, species composition, and beta diversity were used as response variables of biodiversity. The number of gastrotrichs, macrodasyids, and chaetonotids species was mostly explained by sediment sorting and the highest richness was detected in poorly sorted sediments. Species composition and beta diversity were correlated with tidal zone, location, and average grain size, and the highest turnover of species was expected on islands. The general diversity patterns observed in our study that were explained by sediment textures, tidal zones, and localities, are expected to be observed along other marine coastlines in the world and may be correlated with sediment transport and deposition processes.