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

GATTÁS, FLORENCIA; A. VINOCUR; GRAZIANO, M; DO SANTOS AFONSO, M; H. PIZARRO; CATALDO, D.

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2016

0944-1344

Multiple anthropogenic stressors act simultaneously on the environment, withconsequences different from those caused by single-stressor exposure. Weinvestigated how the interaction between the invasive mussel Limnoperna fortunei anda widely applied herbicide, Roundup Max®, affected freshwater microscopiccommunities and water quality. Further, we compared these results with those inducedby the combination of the mussel and pure glyphosate. We carried out a 34-dayexperiment in outdoor mesocosms, applying the following six treatments: 6 mg L-1 oftechnical-grade glyphosate (G), the equivalent concentration of glyphosate in RoundupMax® (R), 100 mussels (M), the interactions between mussels and herbicide either inthe pure or formulated form (MG and MR, respectively), and control (C). Herbicidessignificantly increased total phosphorus in water; R and MR showed higher initial totalnitrogen and ammonia. R increased picoplankton abundance and caused an 8-foldincrease in phytoplankton, with high turbidity values; G had a lower effect on thesevariables. Herbicide-mussel interaction induced an accelerated dissipation ofglyphosate in water (MG: 6.36 ± 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 ammonia was observed in MR but not in MG. MR and MG had an antagonistic effect on phytoplankton, which showed a drastic reductiondue to grazing, as revealed by M.The presence of mussels led to accelerated periphyton colonization and metaphytondevelopment. R, unlike G, increased pico and phytoplankton growth, and waterturbidity. These variables were decreased in the presence of L. fortunei, probablybecause it grazed on pico and phytoplankton. However, the mussel may have boostedother primary producers which cannot be filtered such as periphyton and metaphyton.