Environmental Drivers and Network Structure of Hylid Anurans in Floating Meadows From Amazonian Oxbow Lakes

Abstract Despite the increasing amount of knowledge available regarding the ecological interactions between species, the dynamics of anurans in aquatic environments are little explored and understood. In this way, our work aims to assess which factors influence the composition and the ecological interactions of hylid anurans in oxbow lakes in the middle Purus River, Amazonas. We sampled three lakes with high, medium and low levels of connectivity twice, once during the flood and then in drought hydrological regimes. Variations in the hylid anuran assemblages and ecological interactions were tested as function of environmental niche, food resources, level of connectivity and hydrological regime. The availability of environmental resources and the availability of food resources were the best factors that explain the distribution of hylid anurans, which were also highly dependent on the variations between the hydrological regimes. The interactions between anurans, macroinvertebrates and macrophytes showed a modular and specialized structure, which varied according to the connectivity and hydrological regime of the lakes. Connectance showed an increasing trend from high to low connectivity lakes, suggesting that anurans had low trophic and environmental specialization in lakes with low connectivity. Hylids found in the lake of medium connectivity had higher values of trophic specialization and modularity. Our results illustrate the role of river-lake connectivity and annual hydrological cycle to maintain the aquatic biota and their interactions, and highlight the importance of floating meadows for the maintenance of biodiversity in floodplains.