Influência da dimensão da floresta ripária nos padrões de qualidade da água e os efeitos toxicológicos in situ e ex situ em Astyanax lacustris

Abstract

The Dourados River basin is of great importance for the municipality of Dourados due to the use of water for public supply, irrigation, watering of animals and industries. However, like many river basins in the world, it has compromised water quality. This commitment is mainly due to the increase in land use and other anthropic activities, arising from the expansion of agricultural areas around water bodies and the disposal of industrial and urban waste, resulting in the release of pollutants. In order to preserve these water sources, it is essential to monitor the quality of the water. Riparian forests are areas associated with water bodies that are relevant for the preservation of water quality, as they act as filters and promote the retention of contaminants that would be transported to water courses. However, the progressive increase in land use promotes the degradation of these forests. In order to promote the conservation of riparian forests, the New Brazilian Forest Code, determined by Law No. 12,651/2012, recommends a size of riparian forest that allows maintaining fundamental functions of the ecosystem. However, it becomes relevant to assess whether such a recommendation is sufficient to guarantee water quality in watersheds. This study aimed to analyze the influence of riparian forest size on the existence of contaminants and the induction of toxicity in water from springs and water bodies in the Dourados River Basin in situ and ex situ bioassays with Astyanax lacustris. The results revealed a predominance of agricultural areas around the sampling points, which results in the disorderly degradation of riparian forests, and consequently, impacts on water quality. Agriculture is responsible for the chemical contamination of water bodies resulting in toxic effects for fish. The proportion of riparian forest evaluated in the water body and in areas of springs were not sufficient to mitigate the toxicity in A. lacustris, in addition, it is believed that for a better efficiency of riparian zones in the conservation of water quality, one should consider in addition to plant structure, site-specific factors. In this way, the type of vegetation to be used and the width would be different in each location, requiring further studies considering the different characteristics of the location, for a better interpretation of the effects of riparian forests and the determination of the adequate width.