The odonates are insects that have a wide range of reproductive, ritualized territorial, and aggressive behaviors. Changes in behavior are the first response of most odonate species to environmental alterations. In this context, the primary objective of the present study was to assess the effects of environmental alterations resulting from shifts in land use on different aspects of the behavioral diversity of adult odonates. Fieldwork was conducted at 92 low-order streams in two different regions of the Brazilian Amazon. To address our main objective, we measured 29 abiotic variables at each stream, together with five morphological and five behavioral traits of the resident odonates. The results indicate a loss of behaviors at sites impacted by anthropogenic changes, as well as variation in some morphological/behavioral traits under specific environmental conditions. We highlight the importance of considering behavioral traits in the development of conservation strategies, given that species with a unique behavioral repertoire may suffer specific types of extinction pressure.

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The veredas are wetland ecosystems responsible for supplying most of the water for rivers and streams in the Cerrado. The veredas’ hydromorfic soils retain a large amount of rainwater, releasing it slowly during drier periods. Therefore, these habitats are often used to build dams for cattle raising. Here we assessed the environmental conditions and beta-diversity of Odonata and Heteroptera on veredas impacted by dams in the Brazilian Cerrado. We sampled biological communities and a set of environmental variables in 13 veredas, six with dams and seven without dams. One limnological variable [oxidation–reduction potential (ORP)] and one landscape metric (% of the altered area) differed among veredas with and without dams. These variables were important predictors of the beta-diversity of both Odonata (R2 = 0.650; p < 0.001) and Heteroptera (R2 = 0.740; p < 0.001). The veredas stand among the most sensitive wetland ecosystems of the Cerrado. In this study, we show, for the first time, that veredas with dams may lose environmental quality resulting in changes in biological communities, especially ecologically unique species. Because the Cerrado naturally goes through approximately 5 months of severe drought, the veredas are critical for the Cerrado’s hydric safety. Therefore, we recommend that cattle-raising activities should rely on artificial water tanks instead of using dams for water storage since it affects ecologically unique species in this poorly known ecosystem.

A major part of the mechanisms that affects species distribution is related to environmental conditions. Within a stream channel the accumulation of substrates like litter, roots, stones, gravel and sand create habitats that act as shelter and/or food source to aquatic communities, in this way supporting, or not, the establishment of different species. Based on this fact we verified the structure of aquatic insect communities in organic and inorganic habitats within Cerrado streams. Tested for differences on genera richness (i), individual abundance (ii) and genera composition (iii), and also (iv) verified if there are any indicator genera, which are faithful and specific to organic or inorganic habitats. Sampled organic (litter) and inorganic (sand and gravel) substrates in five sections of three streams and collected individuals of the orders Ephemeroptera, Plecoptera, Trichoptera, Odonata and Heteroptera (EPTOH). Community composition differed between habitats, with organic ones having higher richness and abundance, besides being the only habitat that presented faithful and specific genera (six). It is argued that this difference may be caused due to shelter and food supply provided by organic substrates.

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