Journal or Publishing Institution: Limnetica
Author(s): Sáenz, M.E. and Di Marzio, W.D.
Article Type: Study
Record ID: 2152
Abstract: The increasing use of glyphosate in Argentina is directly related to the increase of areas cultivated with a glyphosate-tolerant transgenic variety of soybean. That has raised concern about the effects of this herbicide in the pampean aquatic ecosystems. Hence, the ecotoxicity of pure (active ingredient) and commercial grade (Roundup) of the herbicide glyphosate was evaluated towards four green freshwater algae: Scenedesmus acutus, Scenedesmus quadricauda, Chlorella vulgaris, and Raphidocelis subcapitata. Toxic effects of glyphosate were assessed on both short-term (photosynthetic rates, determined as oxygen production) and at long-term (growth of the populations, determined as number of cells). A stimulation of the photosynthetic rate was observed at low herbicide concentrations (hormesis). Pure grade short-term effects on the photosynthetic rates appeared at concentrations between 50 and 166 mg L-1 whereas long-term effects on growth appeared in the 1.55-4 mg L-1 range. The commercial grade resulted more toxic than the pure grade; its long-term effects appeared at concentrations between 0.1-3.7 mg L-1. These concentrations are clearly below the expected environmental concentrations (EEC) for this herbicide. Recovery experiments showed that both the pure grade and the commercial grade had algistatic and not algicidal effects. Possible effects and implications at algal community level regarding competitiveness are discussed.
Keywords: glyphosate, freshwater algae, algal community, Roundup-ready soybean, aquatic ecosystems, ecotoxicity
Citation: Sáenz, M.E. and Di Marzio, W.D., 2009. Ecotoxicity of herbicide glyphosate to four chlorophyceaen freshwater algae. Limnetica, 28(1), pp.149-158.
