CHIRONOMIDAE: COMPOSIÇÃO E ALTERAÇÕES MORFOLÓGICAS NO MENTO ASSOCIADAS ÀS VARIÁVEIS AMBIENTAIS AO LONGO DE UM GRADIENTE LONGITUDINAL EM RIACHOS DO CERRADO

Abstract

Objectives: This study aims to evaluate the influence of environmental variables on the Chironomidae assemblage in streams distributed along a longitudinal gradient of a watershed. Methods: The study was conducted in 15 streams distributed in the upper, middle, and lower zones of the Sucuriú River watershed, located in Mato Grosso do Sul. Organisms were collected using a D-net. The organisms were collected and fixed in 70% alcohol and identified to the genus level. Environmental variation (water temperature, pH, electrical conductivity, dissolved oxygen, total dissolved solids, alkalinity, phosphorus, ammonia, cadmium, and zinc) between zones was analyzed by PCA, while differences in abundance and richness of genera were analyzed by ANOVA with Tukey HSD test. The relationships between environmental variables and genera with deformities were analyzed by Spearman correlation. Results: The composition of the Chironomidae family assemblage varied along the longitudinal gradient. Alkalinity, temperature, and electrical conductivity were higher in streams from the middle and lower zones, while dissolved oxygen and electrical conductivity values ​​were higher in streams from the upper zone. The incidence of deformities in the Chironomidae chin showed an association with cadmium and zinc concentrations in the water and with alkalinity. The incidence of deformities in the genus Rheotanytarsus correlated positively with zinc (rS = 0.62; p = 0.01), Cricotopus with cadmium (rS = 0.56; p = 0.02), while Polypedilum showed a negative correlation with zinc and alkalinity (rS = 0.55; p = 0.03). Conclusion:It is concluded that the composition of the Chironomidae family assemblage and the incidence of ment deformities were directly associated with alkalinity and the concentrations of cadmium and zinc. Therefore, the genera Cricotopus and Rheotanytarsus demonstrated their potential use as indicators of environmental quality.