EFFECT OF THE INTERACTION OF TWO STRESSORS, GLYPHOSATE AND THE INVASIVE MUSSEL LIMNOPERNA FORTUNEI, ON FRESHWATER MICROBIAL COMMUNITIES

PIZARRO, HAYDÉE; DI FIORI, EUGENIA; CATALDO, DANIEL; RAMIREZ, MARINA; RODRÍGUEZ, PATRICIA; DOS SANTOS AFONSO, MARÍA

New Orleans

Conferencia; ASLO 2013 Aquatic Sciences Meeting; 2013

ASLO

A manipulative experiment was carried out to evaluate the effect of glyphosate and the invasive mussel Limnoperna fortunei on freshwater microbial communities (phyto-, bacterio-, zooplankton and periphyton) and physico-chemical variables of the water column. Experimental design consisted of 24 outdoor microcosms (70L) to which different glyphosate concentrations (0, 1, 3 and 6ppm) were applied in combination with L. fortunei (presence or absence), resulting in eight treatments per triplicate. Samples were obtained at days 0, 1, 8, 15 and 26. Glyphosate half-life decreased 74% (p< 0.01) in treatments with mussels respect to mussels absence. Total phosphorous increased with herbicide for all treatments while dissolved phosphate was significantly correlated with glyphosate under L. fortunei presence. Each factor individually had different impacts on the studied biological variables than both factors interacting in the system. Although filtrating mussels reduced planktonic communities abundances, with glyphosate presence the global effect was almost the opposite. Instead, periphyton was stimulated by both variables separately and interacting. Limnoperna fortunei would be participating in glyphosate degradation, accelerating the release of phosphate, impacting in all the microbial communities and altering water quality.