Efeitos ambientais e espaciais sobre a diversidade beta de assembleias de insetos aquáticos em córregos do Cerrado

Abstract

Small streams are ecosystems rich in biodiversity, with assemblages of animals and plants closely linked to local and regional environmental conditions. Thus, biological diversity can be influenced by environmental and spatial factors that shape assemblages in different ecosystems, whether natural or anthropized. The aim of this study was to evaluate the relative importance of environmental and spatial factors on the beta diversity of Trichoptera assemblages in streams of the Sucuriú River basin. Sampling was conducted in 15 streams distributed across the Sucuriú River basin (MS). The organisms were collected using a D-net (500 µm mesh size) with an effort of approximately 3 minutes. In the field, the organisms were preserved in 70% ethanol and, in the laboratory, sorted and identified to the genus taxonomic level. In each stream, limnological variables such as water temperature, dissolved oxygen, pH, electrical conductivity, and total dissolved solids were measured using a multiparameter analyzer. A total of 752 Trichoptera larvae were collected, distributed among 19 genera and 10 families. The genus Smicridea (497 organisms) was the most abundant in the Sucuriú River basin. Abundance was higher in the lowland streams of the basin. Rarefied richness in the upland and midland streams (9.4 genera and 10 genera, respectively) was higher than in the lowland streams (5.4 genera). Spatial factors explained 18% of the taxonomic variation in the Trichoptera assemblages, while environmental factors accounted for only 4% of the variation. Although the conditions in the Sucuriú River basin differ across the three zones, the spatial distribution of the streams was the primary structuring factor for Trichoptera assemblages. In this sense, conservation efforts for these environments should consider not only local environmental conditions but also the regional characteristics of the river basin.