Freshwater periphyton response to technical-grade and two commercial formulations of glyphosate

Abstract

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. https://doi.org/10.25260/EA.19.29.1.0.816