RT Journal Article
SR Electronic
T1 Freshwater dissolved oxygen dynamics: changes due to glyphosate, 2,4-D and their mixture, both under clear and turbid-organic conditions
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.09.02.458549
DO 10.1101/2021.09.02.458549
A1 V.L. Lozano
A1 C.E. Miranda
A1 A.L. Vinocur
A1 C.A. Sabio y García
A1 M.S. Vera
A1 C. González
A1 M.J. Wolansky
A1 H.N. Pizarro
YR 2021
UL http://biorxiv.org/content/early/2021/09/03/2021.09.02.458549.abstract
AB We performed two independent outdoor mesocosm experiments where we measured the variation of DO saturation (DO%) in freshwater after a single input of Roundup Max® (G) (glyphosate-based formulation), AsiMax 50® (2,4-D) (2,4-D-based formulation) and their mixture (M). Two concentration levels were tested; 0.3 mg/L G and 0.135 mg/L 2,4-D (Low; L) and 3 mg/L G and 1.35 mg/L 2,4-D (High; H). We assayed consolidated microbial communities coming from a system in organic turbid eutrophic status and a system in clear mesotrophic status during 21 and 23 days, respectively. A sample of phytoplankton (micro+nano, pico-eukaryotes, pico-cyanobacteria), mixotrophic algae and heterotrophic bacteria was collected to determine abundances at each of four sampling dates. The clear and turbid systems showed similar, but not synchronized, patterns of daily DO% changes in relation to the controls (DO%v), after exposure to both single and combined formulations. Under glyphosate scenarios (GL, GH, ML and MH), the two types of systems showed similar DO%v but different microbial abundances, being associated to an increase in the micro+nano and pico-eukaryotic phytoplankton fractions for the clear system. In contrast, in the turbid system changes were associated with increased pico-cyanobacteria and decreased mixotrophic algae. Effects of 2,4-D were only observed in the turbid system, leading to decreased micro+nano phytoplankton abundances. Under the turbid scenario, the herbicide mixture at high concentration had a synergistic effect on DO%v and recovery was not detected by the end of the experiment. Our results revealed that herbicides inputs induced changes in phytoplankton abundances that leads to measurable DO variations.Competing Interest StatementThe authors have declared no competing interest.