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

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

ECOTOXICOLOGY

SPRINGER

Año: 2010 vol. 19 p. 710 - 721

0963-9292

Abstract: Argentina is the second largest world producer of soybeans (after the USA) and along with the increase in planted surface and production in the country, glyphosate consumption has grown in the same way. We investigated the effects of Roundup® (glyphosate formulation) on the periphyton colonization. The experiment was carried out over 42 days in ten outdoor mesocosms of different typology: "clear" waters with aquatic macrophytes and/or metaphyton and "turbid" waters with great occurrence of phytoplankton or suspended inorganic matter. The herbicide was added at 8 mg L-1 of the active ingredient (glyphosate) in 5 mesocosms while 5 were left as controls (without Roundup® addition). The estimate of the dissipation rate (k) of glyphosate showed a half-life value of 4.2 days. TP significantly increased in treated mesocosms with a dissipation rate 4 times slower than glyphosate.Roundup® produced a clear delay in periphytic colonization in treated mesocosms and values of the periphytic mass variables (dry weight, ash-free dry weight and chlorophyll a) were always higher in control mesocosms. Despite the mortality of algae, mainly diatoms, cyanobacteria was favored in treated mesocosms. We could also observe that glyphosate produced a long term shift in the typology of mesocosms, "clear" turning to "turbid", which is consistent with the regional trend in shallow lakes in the Pampa plain of Argentina. Based on our findings it is clear that agricultural practices that involve the use of herbicides such as Roundup® affect non-target organisms and the water quality, modifying the structure and functionality of freshwater ecosystems.