Direct effect of different concentrations of glyphosate formulation Roundup® on the photosynthetic performance of lotic macroalgae

• Grant number: 12/20551-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2013
• End date: December 31, 2013
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Ciro Cesar Zanini Branco
• Grantee: Lucas Kortz Vilas Boas
• Host Institution: Faculdade de Ciências e Letras (FCL-ASSIS). Universidade Estadual Paulista (UNESP). Campus de Assis. Assis , SP, Brazil

Abstract

Glyphosate is a molecule widely used nowadays as an herbicide to fight the invasion of undesired plants in agriculture production. It was first synthesized in the 1960s and commercially introduced in the 1970s. Its active principle acts in the shikimate pathway, inhibiting the enzyme 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS) and preventing the production of aromatic amino acids and proteins synthesis, therefore causing the plant's death. Several studies describe the problems caused by the intoxication of glyphosate in several ecosystems and organisms, among them the primary producers of lotic ecosystems, especially algae, by having a similar metabolism to that of the superior plants. The usage of macroalgae as indicators for herbicides pollution in the lotic environment is recommended because these organisms, for being benthic, suffer all the direct effects produced by the pollutant, besides being seen in plain sight and being responsible for a significant part of the primary production in these ecosystems. In this project, we pretend to evaluate the effects of glyphosate herbicide on the photosynthetic response of macroalgae species that occur in lotic Brazilian environments. For that, the macroalgae will be submitted to 3 different treatments, with 3 different concentrations of glyphosate Roundup® formula. The treatments will simulate, respectively, a residual charge (0,35 mg/L), the concentration recommended for plant control in terrestrial and aquatic environments (3,5 mg/L) and, finally, a high pollutant charge (35 mg/L). The samples will be made in triplicate analyzed on 4-time occasions: I) one (1) day of Roundup® herbicide exposition (T1), II) seven (7) days (t2), III) fourteen (14) days (t3), and twenty-one (21) days (t4). The photosynthetic performance will be evaluated through the chlorophyll fluorescence measure and the O2 evolution. After the analysis, the samples will go through a pigment analysis. Obtained data will be submitted to statistical tests. Obtained data will be submitted to descriptive statistics and the difference between treatments will be evaluated through analysis of variance (ANOVA, one-way) and the Tukey test.(AU)