Influência da piscicultura na qualidade da água da barragem Saulo Maia

Abstract

Water is a fundamental natural resource for the life of living beings on Earth, and when it comes to availability, Brazil is privileged for having a large part of the freshwater reserve. Despite its importance, the intensification of polluting activities has contributed to the scarcity. Anthropogenic activities, such as disposal of untreated domestic and industrial sewage have been influencing water quality, as well as fish farming. The biggest environmental problem of fish farming is related to its effluents with great potential for pollution of natural waters. In view of this, the objective of this work was to evaluate the influence of fish farming on the water quality of the Saulo Maia Dam. To carry out this study, collections were carried out between the months of September and November 2022, near the shore of the Saulo Maia Dam, where the water was recently used in fish farming, with the creation of Tilapia. The physicochemical parameters analyzed were pH, conductivity, turbidity, dissolved oxygen, carbon dioxide, total alkalinity, magnesium, calcium, total hardness, chloride, total phosphorus, nitrate, sulfate and salinity, which followed the methodologies established in the Standard Methods for the Examination of Water and Wastewater, with the exception of the ammonia analysis which was based on the Standard Test Methods for Ammonia Nitrogen in Water (ASTM D1426-08) in order to identify the presence of a contaminating agent. To determine the presence or absence of total coliforms and Escherichia coli, the Colilert® enzymatic substrate technique was used. The ecotoxicity tests were based on NBR ABNT 12.648/2011, using the species Chlorella vulgaris. From the results obtained, for the physical-chemical parameters analyzed, the samples were within the limits established by CONAMA Resolution 357/2005, with the exception of the phosphorus parameter, which was above the established in most collections. In the bacteriological analysis, the presence of total coliforms and Escherichia coli was verified in all samples. In ecotoxicological analyses, chronic ecotoxicity was not observed for the test organism used. Therefore, it can be concluded that there was an influence of fish farming on the quality of the analyzed water, being observed mainly by the concentration of total phosphorus in the first collection, however, an improvement in the quality of the water is observed over time, since the place is disabled for this activity. Thus, the water can be considered suitable for human consumption, after conventional treatment.