Helmintofauna e macroinvertebrados bentônicos como indicadores biológicos do córrego São Pedro - Juiz de Fora

Abstract

The São Pedro stream, located in Juiz de Fora (MG), is an important water body within the Paraibuna River basin, but faces increasing pressures due to the inappropriate disposal of untreated domestic wastewater. This study aimed to evaluate water quality through an integrated analysis of helminth fauna and the benthic macroinvertebrate community in sediments across four sampling points (two rural and two urban), correlating the findings with water physical-chemical variables. Sediment samples were obtained using a Petersen grab for macroinvertebrate sorting in a 210 µm mesh sieve, and parasitological scanning of helminth eggs was conducted via Hoffman and Faust techniques. Physical-chemical variables were measured in the field using a multiparameter probe. The environmental results indicated a severe degradation gradient, evidenced by high electrical conductivity values and and low dissolved oxygen concentrations in urban stretches, with a reduction from over 6.00 mg/L in the rural area to as low as 2.51 mg/L at the urban point. The macroinvertebrate community (830 specimens collected) revealed an expressive loss of ecological integrity in urban areas, with an almost absolute dominance of taxa tolerant to organic pollution: Chironomidae accounted for 99.5% of the fauna in Urban 1, whereas the subfamily Tubificinae (Oligochaeta) represented 99.4% of the organisms in Urban 2. In the parasitological analysis, the Faust technique detected the presence of an Ascaridea egg exclusively in Urban point 1, confirming local sanitary vulnerability. The integrated approach demonstrated that the joint assessment of ecological and sanitary bioindicators provides a robust diagnosis of the degradation of the São Pedro stream, showing that the compromise of aquatic biota integrity coincides with the introduction of public health-relevant pathogens in the impacted areas, emphasizing the urgent need for basic sanitation infrastructure improvements.