New evidences of Roundup (glyphosate formulation) impact on the periphyton community and the water quality of freshwater ecosystems

VERA, M. S; LAGOMARSINO, L.; SYLVESTER, M; PÉREZ, G. L.; RODRÍGUEZ, P. L.; MUGNI, H; SINISTRO, R.; FERRARO, M.; BONETTO, C.; ZAGARESE, H.; PIZARRO, H.

ECOTOXICOLOGY

SPRINGER

Año: 2010 vol. 19 p. 710 - 721

0963-9292

Argentina is the second largest world producerof soybeans (after the USA) and along with the increase inplanted surface and production in the country, glyphosateconsumption has grown in the same way. We investigatedthe effects of Roundup (glyphosate formulation) on theperiphyton colonization. The experiment was carried outover 42 days in ten outdoor mesocosms of differenttypology: ‘‘clear’’ waters with aquatic macrophytes and/ormetaphyton and ‘‘turbid’’ waters with great occurrence ofphytoplankton or suspended inorganic matter. The herbicidewas added at 8 mg L-1 of the active ingredient (glyphosate)in five mesocosms while five were left as controls(without Roundup addition). The estimate of the dissipationrate (k) of glyphosate showed a half-life value of4.2 days. Total phosphorus significantly increased intreated mesocosms due to Roundup degradation whatfavored eutrophication process. Roundup produced aclear delay in periphytic colonization in treated mesocosmsand values of the periphytic mass variables (dry weight,ash-free dry weight and chlorophyll a) were always higherin control mesocosms. Despite the mortality of algae,mainly diatoms, cyanobacteria was favored in treatedmesocosms. It was observed that glyphosate produced along term shift in the typology of mesocosms, ‘‘clear’’turning to ‘‘turbid’’, which is consistent with the regionaltrend in shallow lakes in the Pampa plain of Argentina.Based on our findings it is clear that agricultural practicesthat involve the use of herbicides such as Roundup affectnon-target organisms and the water quality, modifying thestructure and functionality of freshwater ecosystems.