Invasive species versus pollutants: Potential of Limnoperna fortunei to degrade glyphosate-based commercial formulations

GATTÁS, FLORENCIA; ESPINOSA, MARIELA; BABAY, PAOLA; PIZARRO, HAYDÉE; CATALDO, DANIEL

ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2020 vol. 201

0147-6513

The intensive use of glyphosate in industrial agriculture may lead to freshwater contamination, encouragingstudies of its toxic effect on non-target aquatic organisms. Glyphosate-based commercial formulations containadjuvants, making them even more toxic than the active ingredient (a.i.) itself. The golden mussel Limnopernafortunei is a freshwater invasive species which has been found to increase glyphosate dissipation in water and toaccelerate eutrophication. The aim of this study is to evaluate the capability of L. fortunei to reduce the concentrationof glyphosate in two commercial formulations, Roundup Max® and Glifosato Atanor®. Results werecompared with the decay of the a.i. alone and in presence of mussels. Evasive response and toxicity tests wereperformed in a first set of trials to analyze the response of L. fortunei exposed to Roundup Max® and GlifosatoAtanor®. Subsequently, we conducted a 21-day degradation experiment in 2.6-L microcosms applying the followingtreatments: 6 mg L−1 of technical-grade glyphosate (G), Glifosato Atanor® (A), Roundup Max® (R), 20mussels in dechlorinated tap water (M), and the combination of mussels and herbicide either in the technicalgrade(MG) or formulated form (MA and MR) (all by triplicate). Samples were collected at days 0, 1, 7, 14 and21. No significant differences in glyphosate decay were found between treatments with mussels (MG:2.03 ± 0.40 mg L−1; MA: 1.60 ± 0.32 mg L−1; MR: 1.81 ± 0.21 mg L−1), between glyphosate as a.i. and thecommercial formulations, and between the commercial formulations, suggesting that the adjuvants did not affectthe degrading potential of L. fortunei. In addition to the acceleration of glyphosate dissipation in water, there wasan increase in the concentration of dissolved nutrients in water (N?NH4+ and P-PO43-) even higher than thatcaused by the filtering activity of the mussels, probably resulting from stress or from the degradation of glyphosateand adjuvants. We believe that a larger bioavailability of these nutrients due to glyphosate metabolizationmediated by mussels would accelerate eutrophication processes in natural water bodies. The approachused here, where L. fortunei was exposed to two commercial formulations actually used in agricultural practices,sheds light on the potential impact of glyphosate decay on water bodies invaded by this species.