Partitioning of macroinvertebrate assemblages across temporary pools in an intermittent dryland river

This is the authors' abstract. We don't add key points for this paper.

Streams in arid regions are seen as mosaics of spatial/temporal landscapes, with high environmental heterogeneity and exerting strong influence on patterns, structure, and diversity of biotic communities. This study describes the richness and density of benthic macroinvertebrates in temporary pools across different sections of a dryland intermittent river catchment and characterizes the diversity partitioning at different spatial scales across the longitudinal gradient of the river. We hypothesized that the diversity of invertebrates is not homogeneously distributed among the different spatial scales but concentrated at the finer levels of pools and river reaches. The study was conducted in an intermittent river catchment in semiarid Brazil. Sampling was performed hierarchically, including 3 segments of the river (upper, middle, and a tributary), 3 reaches per segment, 3 sites per reach, and 3 microhabitats per site (n = 81). Macroinvertebrate diversity was evaluated at scales of river segment (β4), reach (β3), site (β2), and microhabitat (β1). Habitat structure was composed of a diverse array of elements that varied spatially. Scale-dependent spatial segregation of community composition was observed on macroinvertebrate assemblages. Diversity partitioning analysis reinforced the importance of broader spatial scales (β4) and lesser importance of finer spatial scales (β1 and β2) for the regional diversity in the dryland river catchment study site. Our observations reflect a combination of homogenization of assemblage composition and reduced diversity at finer scales, with a greater contribution of broader scales to the diversity.