Evaluation of ecotoxicological effects of livestock products and sugarcane pesticides to amphibians.

Abstract

Sugarcane is the most efficient first-generation source of ethanol in the market, which has contributed to the rapid expansion of its crops and generated concerns related to its environmental impacts to Brazilian territory. One of the alternatives that have been considered to avoid the removal of native vegetation from Brazilian biomes is the expansion of energy crops in degraded or underutilized pastures by "pasture intensification" process, which aims to allocate the same number of animals in smaller areas and releasing pasture areas for the establishment of new sugarcane crops. However, these processes require several management practices that include fertilizers and pesticides application, which may cause adverse effects on non-target ecosystems and communities. Aquatic environment is one of the main targets affected by agriculture and livestock products, and their organisms are especially vulnerable to the action of these compounds. In tropical areas, agricultural activities of sugarcane are intensified during the rainy season, which coincides with the period of occurrence and reproduction for most species of amphibians. In this study, we aimed to evaluate the impacts caused by the use of agrochemicals associated with pasture and sugarcane crops on the dynamics and structure of amphibian communities. To this end, tadpoles will be exposed to the pesticides and/or fertilizers in open ecosystem models (mesocosmos), which will be established in the experimental unit of the Center for Water Resources and Environmental Studies (CRHEA) (EESC/USP). Field simulations will be performed to analyze the physical, chemical and biological consequences of pesticides use and pasture intensification in freshwater systems, considering natural variations of relevant abiotic factors and thus establishing a more realistic condition of the process. Further laboratory studies (acute toxicity, avoidance behavior and biomarkers) will also be conducted as a support in the evaluation of sensitivity and toxicity of sugarcane pesticides to tropical amphibians.