Atributos ecológicos de macroinvertebrados bentônicos em um rio costeiro tropical sujeito a múltiplos fatores de perturbação

Abstract

Aquatic ecosystems are subject to various human-induced disturbances, including land use and land cover change, pollution, biological invasions, and climate change, and they are also affected by natural variations, such as seasonality. Benthic macroinvertebrate communities have been widely used to assess ecological conditions, as these organisms are sensitive to environmental changes and exhibit varying degrees of tolerance to disturbances. This study aimed to evaluate the ecological attributes of benthic macroinvertebrates along a gradient of environmental conditions in a coastal river exposed to multiple disturbance factors. Sampling was conducted quarterly, in March, June, September, and December 2024, at 22 sites along the Guaraguaçu River basin in Paraná. The sampling sites encompass five spatial zones with different environmental conditions, including sites in the main channel of the river, both upstream and downstream of the confluence with the Pery River, along the Pery River, and in the Pombas River. Ecological descriptors, including richness, abundance, Shannon diversity index, Pielou’s evenness, Berger-Parker index, and metrics related to the organization of functional trophic groups (FTGs) and tolerance to environmental degradation, were calculated. A two-way ANOVA was performed to assess the influence of the spatial gradient of environmental conditions and seasonality on these descriptors, including their interactive effects, with differences between levels identified by marginal means (EMMeans). The structure of the benthic community varied significantly along both spatial and seasonal gradients. The Pery River zones and areas near the Wastewater Treatment Plant (WWTP) exhibited higher abundance, diversity, and evenness, associated with the predominance of pollution-tolerant organisms, indicating greater environmental impact. In contrast, the upstream regions of the Guaraguaçu River and the Pombas tributary harbored intolerant taxa, reflecting better ecological conditions. These results indicate that the functional composition of the community is a more robust indicator of environmental quality than traditional metrics of diversity or abundance. Collectively, these patterns demonstrate environmental degradation and functional imbalance in the impacted areas, reinforcing the use of macroinvertebrates as bioindicators of environmental integrity.