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

PIZARRO, H.; DI FIORI, E.; SINISTRO, R.; RAMÍREZ, M.; RODRÍGUEZ, PATRICIA; VINOCUR, ALICIA; CATALDO, DANIEL

ECOTOXICOLOGY

SPRINGER

Lugar: Berlin; Año: 2016 vol. 25 p. 56 - 68

0963-9292

The study of the joint effect of multipleanthropogenic stressors is important because the emergingconsequences are often unpredictable on the basis ofknowledge of single effects. We explored the joint impactof glyphosate and the invasive golden mussel Limnopernafortunei on freshwater phytoplankton, bacterioplankton andperiphyton, and on the physical and chemical properties ofthe water. We manipulated both stressors simultaneously ina 25-day experiment using outdoor mesocosms; we assayedtechnical-grade glyphosate acid at four concentrations: 0,1, 3 and 6 mg gly L-1 under scenarios with and withoutmussels. The addition of the glyphosate significantlyincreased total phosphorus according to the concentrationused; the high clearance rate of L. fortunei significantlydecreased phytoplanktonic abundance leading to low valuesof turbidity. The mussel significantly stimulated thedevelopment of filamentous green algae (metaphyton).Interestingly, the combined effect revealed that L. fortuneiaccelerated the dissipation of glyphosate, which showed a4-fold decrease in its half-life; this promoted the rapidbioavailability of glyphosate-derived phosphorus in thewater. The interaction had a synergistic effect on solublereactive phosphorus concentrations and was directlydependent on the concentration of glyphosate. A synergisticeffect was also observed on bacterioplankton, waterturbidity and metaphyton, thus inducing enhanced andrapid eutrophication. The ability of mussels to reduceglyphosate in water may be valued as positive, but ourresults allow us to predict that the invasion of Limnopernafortunei in natural freshwater systems contaminated byglyphosate will accelerate the negative impact of the herbicideassociated with eutrophication.