Reaction of biofilms (cyanobacterial, diatom and green algae) from lake Balaton and river Danube to herbicide preparation ROUNDUP and its components (glyphosate, POEA)

The behavior of biofilms developing during 6 weeks on sheets of glass fixed to AKK-1® type carrier buoy in River Danube (Green Island, Budapest) and in Lake Balaton (Tihany Bay) in spring time was investigated in aquaria exposed to glyphosate at concentrations of 100 and 1000 µg/l for 6 and 4 weeks, respectively. The effects of adjuvant POEA and formulated herbicide ROUNDUP® at glyphosate equivalent concentrations were also tested. Sensitivities of biofilms from River Danube and Lake Balaton were different under laboratory conditions. No adverse effects of POEA were determined on the well-estimable biofilm originated from River Danube, while glyphosate caused a 30% decrease in 10 weeks. Realignment of biofilms was typical, the initial ratio of diatom (Bacillariophyceae) and cyanobacteria (Cyanobacteria) decreased, and these species were replaced by a filamentous green alga (Chlorophyta) population