Utilização de espécies de cladóceros (Crustacea: Brachiopoda) em ensaios ecotoxicológicos

Abstract

The intense human activity on nature contributes to its degradation, being the aquatic environment, among the natural resources, the most susceptible to impacts of human activity, since they are used as a place of disposal of domestic and industrial effluents. Ecotoxicology has emerged as a science that studies and evaluates the effects of physical and chemical agents on living organisms and their natural organizations (populations, communities and ecosystems). Through biomonitoring and toxicity tests, organisms are used as tools for a response (acute or chronic toxicity), given that only physical-chemical analyzes are not sufficient to determine potential effects on biota. The cladocerans, known as "water fleas" (Crustacea: Brachiopoda) are planktonic and filtering organisms that feed on particles, algae and other organic debris in aquatic environments in which they are inserted, very sensitive to environmental changes and, given to this characteristic, they are submitted to the most diverse types of pollutants in ecotoxicological tests, since they are in initial levels of the food chain, serving as food preferentially for fishes, being able to affect other instances of the food chain. In a literature review of the last 10 years (2009-2018), the exotic species Daphnia similis and Ceriodaphnia dubia were the most used species for acute and chronic toxicity studies, respectively, considering tests that include environments contaminated with heavy metals (As, Cd, Cr, Cu, Zn), chemical and nanoparticulate (Ag, Ti), besides its use for the measurement of river and basin quality. The species Ceriodaphnia silvestrii and Daphnia magna were used to compose analyzes of water bodies under the influence of agrochemicals and xenobiotics, also serving as a tool to trace sources of pollution. The native species Daphnia laevis and Macrothrix flabelligera were the least selected to compose studies. The criteria used to select the most used species were: wide distribution of organisms, short life cycle, rapid reproduction and, associated with these characteristics, establishment of protocols by the Brazilian Association of Technical Standards (ABNT) and CETESB, regarding the preparation, management and use of these species. It was concluded that the versatility and differences in the sensitivity of the organisms to the tests that were submitted contribute to the selection of these, including the technical and legal support of the existing protocols, however, it is important to continue research that has the purpose of inserting other species native to the legal regulations, for greater reliability in the results, besides works that increasingly aim at the maintenance, control and conservation of water bodies, consolidating cladocerans as important tools of ecotoxicology and biomonitoring