Toxic degree evaluation for fish farming in Pernambuco (Brasil)

Abstract

The Sao Francisco Sub-Middle excerpt is considered favorable for fish farming region. Despite the economic and social importance of this activity, the use of antibiotics, hormones for reversal of fingerlings and the nitrogen and phosphate addition through the feed, represent potentially generating sources of environmental impacts. Ecotoxicological studies associated with physicochemical and biological assessments provide information about the wastewater of fish farming and its impacts, contributing to the formulation of public policies for monitoring wastewater released in water bodies. Ahead this, the present study was carried out on an excaved tank fish farming with Oreochromis niloticus cultivation in Pernambuco (Brazil), in the semi-arid region. Ecotoxicological parameters were evaluated, physico-chemical and biological agents on six sampling points. The results showed that when comparing the data points in the wastewater before and after the treatment by phytoremediation it is observed that there was a values decrease for the physical and chemical parameters, with high rate of dissolved oxygen. However, for the biological variables there was registered an increase in, calling attention to Itaparica reservoir, with cyanobacteria densities above the limit permitted by CONAMA Resolution 357/05. Since many of these parameters indicate eutrophication and may interfere with the water and in fish quality. Water and wastewater from fish farming in excavated tank, as well as oxytetracycline antibiotic, not accounted for toxicity for microcrustaceous Daphnia similis and Danio rerio fish used in ecotoxicological tests. However, sublethal effects observed in D. rerio call attention to the impacts continued in a long-term exposure. The 17α-methyltestosterone hormone caused acute toxicity to D. similis and D. rerio , showing direct impact on the aquatic ecosystem. The results emphasize the need to monitor the ecotoxicological effects of fish farming activity and its impacts on water resources, as well as the regulation of pharmaceutical products used in crops.