Processes contributing to rotifer community assembly in shallow temporary aridland waters

Understanding how local conditions and dispersal dynamics structure communities of passively dispersing aquatic invertebrates remains uncertain, especially in aridland systems. In these systems, dispersal is irregular and successful colonization is subject to priority effects. To investigate these factors, we compared rotifer species composition from Chihuahuan Desert rock pools, playas, and tanks. (1) We found 132 species with high beta-dissimilarity among sites (> 0.8). (2) Correlation between species richness and habitat area was significant, but weak, for all sites. (3) Dissimilarity analyses, supported by negative Dispersal-Niche Continuum Index (DNCI) values, showed that stochastic processes dominate community assembly. (4) We examined influence of three important environmental variables on richness and community structure: hydroperiod, algal mat and macrophyte development, and conductivity; we also examined how rotifer trophi type (a functional trait) affected DNCI and identified indicator species. Hydroperiod was important for playas and tanks, but not rock pools. Conductivity had a strong influence. Richness was greatest in habitats with highest amounts of vegetation. Environmental factors explained similar to 12% of variation in community composition, indicating that while deterministic processes are significant, stochastic processes dominate in these systems. We provide a conceptual model that highlights the distinctive of nature aquatic communities in aridlands compared to temperate regions.

Automated summary

This study investigates the species composition of rotifers in rock pools, playas, and tanks in aridland systems, and reveals high beta-dissimilarity among different sites. While environmental factors have some explanatory power for community composition, stochastic processes dominate in these systems.