Differential impact of Limnoperna fortunei-herbicide interaction between Roundup Max® and glyphosate on freshwater microscopic communities

. F. GATTÁS; A. VINOCUR; M. GRAZIANO; M. DOS SANTOS AFONSO; H. PIZARRO; CATALDO DANIEL HUGO

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2016

0944-1344

Multiple anthropogenic stressors act simultaneouslyon the environment, with consequences different from thosecaused by single-stressor exposure. We investigated how thecombination of the invasive mussel Limnoperna fortunei anda widely applied herbicide, Roundup Max®, affected freshwatermicroscopic communities and water quality. Further, wecompared these results with those induced by the combinationof the mussel and technical-grade glyphosate.We carried out a34-day experiment in outdoor mesocosms, applying the followingsix treatments: 6 mg L−1 of technical-grade glyphosate(G), the equivalent concentration of glyphosate in RoundupMax® (R), 100 mussels (M), the combination of mussels andherbicide either in the technical-grade or formulated form(MG and MR, respectively), and control (C). Herbicides significantlyincreased total phosphorus in water; R and MRshowed greater initial total nitrogen and ammonium. R increasedpicoplankton abundance and caused an eightfold increasein phytoplankton, with high turbidity values; G had alower effect on these variables. Herbicide-mussel combinationinduced an accelerated dissipation of glyphosate in water (MG6.36 ± 0.83 mg G g DW−1 day−1 and MR 5.16 ± 1.26 mg G gDW−1 day−1). A synergistic effect on ammonium was observedin MRbut not inMG. MRandMGhad an antagonisticeffect on phytoplankton, which showed a drastic reductiondue to grazing, as revealed by M. We provide evidence ofdifferential effects of Roundup Max® and technical-gradeglyphosate over water quality and microscopic communities,and in combination with mussels. However, in the combinationof mussels and herbicides, mussels seem to play a leadingrole. In the presence of L. fortunei, the effects of higher nutrientavailability provided by herbicides addition werecounteracted by the filtration activity of mussels, which releasednutrients, grazed on picoplankton and phytoplankton,and boosted the development of other primary producers, periphytonand metaphyton.