Relations of habitat integrity and spatial structure on the Gerromorpha community (Hemiptera: Heteroptera) in streams under the influence of protected area in Oriental Amazon

The community of semiaquatic insects (Gerromorpha) is related to forest cover and habitat integrity, as well as spatial factors such as the distance between streams. Therefore, our objective was to evaluate the effect of spatial structure and habitat integrity (HII) on the composition, abundance and richness of Gerromorpha in streams across an environmental gradient inside and outside the Floresta Nacional de Carajás (FLONA Carajás). Our hypotheses: i) habitat integrity has a positive effect on the richness and abundance of Gerromorpha, since the availability of resources provides the existence of a greater number of species and consequently a greater abundance and richness of these species; ii) species composition is structured by habitat integrity, considering that preserved sites provide better conditions for the coexistence of specialist species or rare species; iii) the composition of Gerromorpha will be structured by the distance between streams (as some species may have dispersal limitations). Sampling was conducted in 10 streams (five inside of a protected area and five around protected areas). To determine habitat integrity, we used the Habitat Integrity Index (HII). For data analysis, we used linear models to test the effect of HII on richness and abundance. Finally, we used db-RDA to test for differences in species composition in relation to HII and spatial structure. Our results richness and abundance are not influenced by HII not corroborating our hypotheses. Furthermore, our results showed that the species composition of Gerromorpha is influenced only by spatial structure, and not for HII, confirming our hypothesis. This lack of differences can be attributed to the small variation in HII between the streams sampled. Our findings highlight the importance of spatial structure for the composition of Gerromorpha species and of the forest for maintaining habitat integrity and aquatic biodiversity.