Impact of multiple anthropogenic stressors on freshwater: 4 how do glyphosate and the invasive mussel Limnoperna fortunei 5 affect microbial communities and water quality?

HAYDEE PIZARRO; EUGENIA DI FIORI , HAYDEE PIZARRO , MARIA DOSSANTOS AFONSO , DANIEL CATALDO; RODRIGO SINISTRO; MARINA RAMıREZ; PATRICIA RODRıGUEZ; CATALDO; ALICIA VINOCUR; ESTEBAN PAOLUCCI; VALENTÍN LEITES Y DEMETRIO BOLTOVSKOY; DANIEL CATALDO

ECOTOXICOLOGY

SPRINGER

Lugar: Berlin; Año: 2015

0963-9292

The study of the joint effect of multiple11 anthropogenic stressors is important because the emerging12 consequences are often unpredictable on the basis of13 knowledge of single effects. We explored the joint impact14 of glyphosate and the invasive golden mussel Limnoperna15 fortunei on freshwater phytoplankton, bacterioplankton and16 periphyton, and on the physical and chemical properties of17 the water. We manipulated both stressors simultaneously in18 a 25-day experiment using outdoor mesocosms; we assayed19 technical-grade glyphosate acid at four concentrations: 0,20 1, 3 and 6 mg glyL-1 under scenarios with and without21 mussels. The addition of the glyphosate significantly22 increased total phosphorus according to the concentration23 used; the high clearance rate of L. fortunei significantly24 decreased phytoplanktonic abundance leading to low val-25 ues of turbidity. The mussel significantly stimulated the26 development of filamentous green algae (metaphyton).27 Interestingly, the combined effect revealed that L. fortunei28 accelerated the dissipation of glyphosate, which showed a29 4-fold decrease in its half-life; this promoted the rapid30 bioavailability of glyphosate-derived phosphorus in thewater. The interaction had a synergistic effect on soluble 31reactive phosphorus concentrations and was directly 32dependent on the concentration of glyphosate. A syner- 33gistic effect was also observed on bacterioplankton, water 34turbidity and metaphyton, thus inducing enhanced and 35rapid eutrophication. The ability of mussels to reduce 36glyphosate in water may be valued as positive, but our 37results allow us to predict that the invasion of Limnoperna 38fortunei in natural freshwater systems contaminated by 39glyphosate will accelerate the negative impact of the her- 40bicide associated with eutrophication.