Impacts of pesticides and vinasse on the composition and functional diversity of aquatic macroinvertebrates exposed in a mesocosm system.

Modern agriculture plays a significant role in the global economy. However, the continuous use of pesticides and fertilizers raises concerns about aquatic pollution and its effects on indigenous organisms. Thus, this study investigated the impact of the pesticides Regent® 800 WG (active ingredient - a.i. fipronil) and DMA® 806 BR (a.i. 2,4-D), as well as sugarcane vinasse, an ethanol industry byproduct applied in sugarcane crops as fertilizer, individually and in mixtures, on the functional diversity of benthic macroinvertebrates at a mesocosm scale. For that, open-air mesocosms were used, in which the effects of contaminants were evaluated over time (1, 7, 14, 28, 75, and 150 days after contamination). The macroinvertebrate community was monitored using colonization structures, while physicochemical parameters, metals, and pesticides were analyzed throughout the experiment. In the control and 2,4-D-treated mesocosms, collectors, predators, and scrapers were the predominant organisms. In mesocosms contaminated with fipronil and pesticide mixture, predators such as Odonata and Tanypodinae disappeared after contamination. In the pesticide and vinasse mixture treatment, collectors, filter feeders, and scrapers predominated over time. Functional richness and diversity were reduced in the pesticide mixture. Contamination by the mixture of pesticides and vinasse reduced functional diversity, due to the disappearance of predators and tolerant organisms. Therefore, the functionality of the macroinvertebrate fauna may be affected by the application of these contaminants in areas close to sugarcane cultivation. These effects represent a risk to the balance of aquatic ecosystems, compromising trophic chains, ecological functions, and the overall health of the aquatic ecosystem.