Environmental thresholds of skater bugs (Heteroptera, Gerromorpha) as an indicator of environmental change in Amazon streams

Abstract

Freshwater ecosystems, under the influence of human activities, are subject to multiple environmental stressors that lead to biodiversity loss, and the habitat modification. In recent years, different various organisms have been used as bioindicators to detect environmental changes by their ability to perceive changes in community attributes. A good example is the semiaquatic bedbugs of the Gerromorpha infra order that act as predators and are sensitive to subtle changes in environmental conditions. Our research aimed to investigate the responses of Gerromorpha communities, genera and species along an environmental gradient in 45 Amazon streams. The environmental gradient was assessed utilizing the Habitat Integrity Index (HII) across the sampled streams, yielding a collection of 2.212 specimens representing three families, seven genera, and 36 species. The habitat integrity, represented by the HII, showed a positive relationship with both species richness and the richness of genera of Gerromorpha, underscoring that both species and genera respond to environmental change in the analyzed habitats. Brachymetra lata from the Gerridae family and Rhagovelia jubata, Rhagovelia elegans from the Veliidae family were the most sensitive taxa with a positive relationship to HII. Streams characterized by heightened anthropogenic disturbance and reduced riparian vegetation were associated with a biodiversity pattern marked by increased abundance and frequency of generalist species and reduced genus frequency within the Veliidae family. We hope that the results of this study will contribute to future biomonitoring programs in response to habitat and species loss, aiming to assist decision-making to protect and restore riparian vegetation areas.