Entomofauna associada à macrófitas aquáticas em uma lagoa na RPPN Fazenda São Francisco, Bacabal, Maranhão

Abstract

Aquatic macrophytes are macroscopic forms of aquatic vegetation whose active photosynthesizing parts are permanently or for a few months of the year totally submerged, partially submerged or even floating. These types of vegetation play an important biological role in aquatic environments by providing a greater diversity and richness of animal groups in the littoral zone of lakes and water reservoirs. Aquatic macrophyte banks are among the most favorable environments for the establishment of aquatic insect communities, as they contribute to greater habitat heterogeneity and serve as a food source for various animal species. The aim of this study was to analyze the composition and structure of the entomofauna associated with four species of aquatic macrophytes in a stream at the RPPN Fazenda São Francisco, Bacabal, Maranhão, Brazil. The samples were collected from a stream located in the RPPN Fazenda São Francisco in the months of May (rainy season) and August (dry season). The macrophytes Nymplaea rudgeana, Pontederia crassipes, Salvinia auriculata and Neptunia oleracea were the species selected to have their associated fauna sampled in this work. Two collection points were selected in the sampling area, approximately 700m apart. A 50cm² quadrant made of PVC was used for the collections. It was positioned on the surface of the water and all the material present within the limits of the quadrant was collected. Four quadrants were sampled at each point, totaling 2m² of sampling area per collection point and per collection station. The entomofauna associated with the macrophytes was sorted, assembled and identified to the lowest possible taxonomic level. Indices of abundance, richness, diversity (Shannon-Wiener) and dominance (Simpson) were used to describe the entomofauna present in the stream, in the seasons analyzed, and that associated with each of the macrophytes. A total of 948 specimens belonging to six orders and 24 morphospecies were collected. The order Coleoptera was the most abundant with approximately 83% of all the fauna present, and also the most diverse with 13 morphospecies. The dry season showed greater abundance and diversity than the rainy season. The abundance and diversity of species differed in relation to the macrophyte evaluated. The results presented here are extremely important for understanding the dynamics of the entomofauna in streams in the central region of Maranhão.