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The modification of landscapes surrounding water bodies leads to changes in limnological characteristics and decreased aquatic biodiversity, such as fish and macroinvertebrates. Aquatic insects are sensitive to changes in aquatic ecosystems and quickly respond to those changes. The aim of this paper was to evaluate the relationship between the compositions of aquatic and semi-aquatic Heteroptera with environmental variables along an environmental gradient in streams at the headwaters of the Xingu River, Brazil. We collected samples from 12 streams belonging to the Suiá-Miçú river basin and tributaries of the Xingu River, in September (dry season), 2008. The Suiá-Miçú river is one of the tributaries on the right bank of the Xingu River, and it is located in the ecotone between the Cerrado and the Amazon rainforest in the area characterized as the “arc of deforestation’’. Insects were sampled in fixed 100 m transections and divided into 20 segments of 5 meters each. To assess the habitat integrity in each stream, the habitat integrity index (HII) was applied. The following environmental variables were measured: electrical conductivity, turbidity, depth, and the normalized difference vegetation index (NDVI). The ordering of species composition was performed with the principal coordinate analysis (PCoA), and the relationship between environmental variables and composition was performed using a Mantel test. Of the 263 individuals collected, distributed in 8 families, there were 20 genera, of these, 12 were from Nepomorpha and 8 from Gerromorpha. The most abundant genera were Limnocoris (n = 121) and Rhagovelia (n = 32). Naucoridae was the most diverse family. Together, the environmental variables explained ~50% of the species distribution (r = 0.49; p = 0.001). These results reinforce the efficacy of aquatic Heteroptera to monitor environmental conditions. Here, in particular, the responses of this group to variations in landscape metrics, environmental integrity, and water variables together demonstrate that it can be useful to indicate the quality of habitat in streams.

Studies on Cladocera biodiversity in Brazilian freshwater ecosystems are intensifying. However, the fauna of some hydrographic regions is still poorly known. We investigated the richness and species composition of cladocerans in lakes of the Pantanal from the state of Mato Grosso (Paraguay hydrographic region), Brazil. In addition, we cataloged the known cladoceran species in each hydrographic region of the state. Occurrence data were obtained from the literature and samples collected from 50 lakes in the northern Pantanal. We recorded 120 cladoceran species from eight families in the state of Mato Grosso. The occurrence of these species was recorded in the Amazon and Paraguay hydrographic regions. We are unaware of studies on cladocerans conducted in the Tocantins-Araguaia hydrographic region. We reported 17 new records in the Pantanal samples (Paraguay hydrographic region). Overall, richness estimates reveal that 72.6% of the state's cladoceran fauna is already known, while for the Paraguay hydrographic region this estimate is 72.2%. In general, the cladocerans from the Amazon and Paraguay regions did not differ. Our findings allow us to infer the need for further studies in the different hydrographic regions found in Mato Grosso in order to improve the knowledge of cladoceran biodiversity. We suggest a greater sampling effort, particularly in the littoral zone of aquatic ecosystems in this state, which can harbor great biodiversity.