Abstract

GONZALEZ, Daniela et al. Freshwater periphyton response to technical-grade and two commercial formulations of glyphosate. Ecol. austral [online]. 2019, vol.29, n.1, pp.20-27. ISSN 1667-782X.

Glyphosate is the most widely used herbicide worldwide. It may reach water bodies and affect microbial communities. We compared the effects of two commercial formulations and technical-grade glyphosate on a freshwater periphytic community. A laboratory bioassay was carried out with four treatments: technicalgrade glyphosate acid, Glifosato II Atanor^®, Roundup Max^®, at a concentration of 3 mg active ingredient/L, and Control. At 2, 5 and 9 days after herbicide application, pigments concentration, dry weight, ash-free dry weight, and periphytic algal density were determined. An increase of Cyanobacteria and a decrease of Chlorophyta and Bacillariophyta abundances were registered in all treatments with the herbicide. This effect was greater when Roundup Max^® and Glifosato II Atanor^® were added, and was lower with technical-grade glyphosate, suggesting that additives in the commercial formulations may enhance glyphosate effects.

Keywords : Periphytic community; Herbicides; Technical-grade glyphosate; Roundup Max^®; Glifosato II Atanor^®; Microcosms.

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