Impacto de agroquímicos en ecosistemas de agua dulce

H. PIZARRO

Buenos Aires

Conferencia; Jornada de Puertas Abiertas ''INTERACCIÓN ENTRE POBLACIONES Y CLIMA: PASADO, PRESENTE Y FUTURO'; 2017

Encuentro Permanente de Asociaciones Científicas (EPAC)

Conferencia plenaria.Agricultural practices carried out worldwide are mainly based on agrochemicals. Glyphosate is a non-selective, broad-spectrum, postemergent herbicide, mainly used for weed control; it is considered safety for environment due to its low toxicity and harmless. Glyphosate is the agrochemical most sold worldwide, due to the large intensive cultivation of genetically modified crops to tolerate it. Also, no-till practices that favor soil integrity include the use of glyphosate for weed control. In Argentina, the use of glyphosate rocketed from the 90´s and today, more than 180 million kg/ha is applied per year. According to our studies, the herbicide is far from being harmless to the environment due to its negative impact on freshwater. The contribution of phosphorus from glyphosate and its availability mediated by biodegradation processes enriches the water favoring eutrophication process. We demonstrated, at ecosystem scale using outdoor mesocosms, the direct effect on microbial communities such as phytoplankton, bacterioplankton, periphyton, which constitute the basis of the community structure of freshwater ecosystems. Some algal groups decreased while certain other components as cyanobacteria appeared as favored. In some cases, as picocyanobacteria, they passed to dominate the water column causing changes in the overall turbidity of the system. We have shown that water quality has deteriorated by glyphosate impact, which is a matter of concern because freshwater systems provide important ecosystem goods and services to humanity. Considering that anthropogenic stressors act jointly in the environment, we have evaluated how glyphosate interacts in water with an invasive species, the golden mussel Limnoperna fortunei, which arrived to Argentina almost simultaneously with the emergence of glyphosate. Our results show that the joint action of both stressors still generates major alterations in biological communities and water quality due to their synergistic interaction.