Comparative impact of two glyphosate-based formulations in interaction with Limnoperna fortunei on freshwater phytoplankton

DE STEFANO, LUCÍA; GATTÁS, FLORENCIA; VINOCUR, A.; CRISTOS, DIEGO; ROJAS, DANTE; CATALDO, D.; H. PIZARRO

ECOLOGICAL INDICATORS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 85 p. 575 - 584

1470-160X

Abstract: Although contamination and invasive species are two of the mostrelevant anthropogenic drivers affecting ecosystems, their joint impacton the environment has been poorly investigated. Glyphosate, directly orindirectly, contaminates freshwater systems which in turn may be invadedby the golden mussel Limnoperna fortunei. Under laboratory conditions, westudied the combined effect of technical-grade glyphosate, Roundup Max®and Glifosato Atanor®, in scenarios with and without L. fortunei, onphytoplankton from Salto Grande Reservoir (Uruguay River, Argentina). Weexpected that the effects of the interaction on phytoplankton and waterquality would vary with the form of herbicide applied. The assay wasconducted for 14 days (Tf) using 3-L bottles as experimental units. Eighttreatments were performed in triplicate: C: Control; M: mussel; G:technical-grade glyphosate acid; R: Roundup Max®; A: Glifosato Atanor®;MG: mussel+technical-grade glyphosate acid, MA: mussel+Glifosato Atanor®and MR: mussel+Roundup Max®. The active ingredient was applied at 6 ppm.The dissipation of glyphosate in water was 1.5 to 2.6 times higher inpresence of mussels. Treatments G and A showed an increase inphytoplankton abundance, mainly the cyanobacteria Microcystis spp. wichrised to 289% and 639% at Tf, respectively, relative to their values atTi. Roundup Max® limited the growth of Microcystis spp., as its abundancedecreased 59% relative to Ti. L. fortunei reduced phytoplanktonabundances at Tf. Evenness increased significantly in M, MG, MR and MA,while it decreased in G, R and A relative to C. The interaction offactors produced a significant synergistic increase in periphyton;periphytic chlorophyll a concentration was 0.81 ± 0.02 μg cm-2 for MR;0.09 ± 0.02 μg cm-2 for MA and 0.02 ± 0.01 μg cm-2 for MG. Limnopernafortunei appeared as the driving force in the interaction. The assaydescribed here allows for the rapid assessment of the impact of thesetypes of agents on freshwater.