Effects of Environmental Changes on Gerromorpha (Heteroptera: Hemiptera) Communities from Amazonian Streams

Abstract

The presence of environmental conditions that are suitable for the development of agricultural and cattle-raising activities has favored the expansion of land use in the Brazilian Amazon. This expansion changes the environmental conditions of aquatic ecosystems by altering the structure of the streambeds and the physicochemical conditions of the water. Therefore, this manuscript aimed to assess the effect of changes in environmental conditions along a gradient of different land uses on the richness and species composition of Gerromorpha (Heteroptera: Hemiptera) communities in streams from the Brazilian Amazon. We sampled Gerromorpha communities and environmental variables (physical structure of the habitat and physicochemical characteristics of the water) in 45 streams in the municipality of Paragominas in the state of Pará, Brazil. We then performed variation partitioning analyses to assess the relative contribution of habitat structure and water physicochemical variables on the richness and species composition. The Habitat Integrity Index (HII), which measures the habitat physical structure, was the best predictor of species richness. The HII and physicochemical variables were jointly the best predictors of species composition. Our results show that Gerromorpha communities respond to gradients of environmental anthropization in the Amazon region, which reinforces the importance of habitat integrity and water quality for the maintenance of Gerromorpha communities.