Assessment of single and combined toxic effects of the antimicrobials florfenicol and oxytetracycline for the aquatic biota focusing in the environmental risk characterization for the tropical ecosystems

Abstract

The florfenicol and oxytetracycline are the widest antimicrobials used to cope with bacterial diseases in fish farming throughout world, including the Brazil. Thus, in the last years, the concern about the contamination of aquatic environments with these two antimicrobials is increasing, since little is known about their possible toxic effects and their ecological risks to non-target organisms, especially for those belonging to tropical regions. In addition, since these two chemicals are usually used by the same fish farmer in the treatment of diseased fish, there is a great possibility that they simultaneously occur in the same aquatic environment. In this research project, therefore, it will intend to investigate the gaps in the knowledge relative to the effects and risks that florfenicol and oxytetracycline could have on the biota belonging to tropical freshwater ecosystems, when both are present alone as well as in mixtures. For this, acute and chronic effects of the florfenicol and oxytetracycline for some native aquatic species from tropical regions will be determined in single toxicity tests and mixture toxicity tests. Also, it will be performed an environmental risk characterization of both florfenicol and oxytetracycline for tropical freshwater ecosystems, considering the specific features of this region. This risk characterization will aim to support public management policies in the use and management of these antimicrobials so that intensive fish farming from tropical regions can use them within a perspective of maintaining of environmental health.