Qualidade ambiental de um arroio a partir do levantamento de invertebrados aquáticos

Abstract

The great demand for water has reserved to stream ecosystems, the key status for the conservation and preservation of water resources. The streams support a significant diversity of aquatic invertebrates, which can be used as adjuvants in water quality investigations. The focus of the research is based on determining the composition of aquatic invertebrates associated with environmental quality parameters. The study was conducted in a 1 km stretch of the Arroio do Bigode, a spring that makes up the Leão River microbasin, in the Laranjeiras do Sul (PR) city, from February to July 2021. The collection of macroinvertebrates was carried out with use of artificial substrates from a 2 L PET bottle containing gravel, in replicas distributed in 3 sampling stations (upstream, intermediate and downstream), kept submerged for a period of 72 days for colonization. Simultaneously with the removal of samples, measurements of physical and chemical variables were performed, using a multiparameter probe and titration kit. Invertebrates were identified at the lowest possible taxonomic level, and the data served to establish environmental quality standards using the BMWP (Biological Monitoring Water Parts) and ASPT (Average Score Per Taxon) index. A total of 538 individuals were captured, distributed in 29 taxonomic groups, consisting of nematodes, molluscs, annelids, crustaceans, insects and mites. In the upstream and intermediate stretches, a greater number of taxa were recorded, with a predominance of collectors, and the sum of families reflected higher scores in the BMWP and ASPT indices. In contrast, in the downstream stretch there was a change in the community, with a reduction in groups of predatory invertebrates, shredders and scrapers, and a respective increase in scavenger-filters. The indices showed that all stations investigated are subject to moderate pollution from diffuse sources of agricultural activities. These interferences manifest themselves distinctly in the limnological conditions of the stream, according to the preservation range and characteristics of the riparian vegetation.