Alpha and beta diversity of freshwater meiofauna at different spatial scales in a Neotropical lotic system

Abstract

Meiofaunal assemblages are important components of benthic communities in freshwater habitats, but studies about their ecology are scarce. In the present study we investigated the spatial and temporal distribution patterns of freshwater meiofaunal taxa, in a lotic system in south-eastern Brazil, assessing α and β diversities through additive partitioning of diversity. At each of six sampling sites, a 50-m transect was divided into five equal sections. Two random samples were collected in each section. Local spatial scales (α and β1) and among areas (β3) made the highest contribution to overall richness, but seasonal variation could be seen. Non-randomness patterns were observed, especially at the lowest and highest spatial scales, showing the effects of local intraspecific aggregation and environmental variability among areas. Temporal scale analysis showed that diversity was highly aggregated at the monthly scale, but sampling location affected these results. Community composition results highlighted the contrasting conditions found at the sampling sites, highlighting β3 as an important component of γ diversity across spatial scales. The effects of different levels of environmental degradation and precipitation on community composition and meiofaunal abundance affected the ability of the community to recover and recolonise the meiobenthos.