Effects of glyphosate and 2,4-D mixture on freshwater phytoplankton and periphyton communities: a microcosms approach

Lozano, Verónica Laura; Vinocur, Alicia; García, Carmen A. Sabio y; Allende, Luz; Cristos, Diego; Rojas, Dante Emanuel; Wolansky, Marcelo Javier; Pizarro, Haydée

doi:10.1016/j.ecoenv.2017.12.006

Cited by 48 publications

(39 citation statements)

References 49 publications

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“…However, we did not observe any significant decrease in Chla content for any of the three submersion period experiments. This absence of adverse effect was also observed by Lozano et al (2018) who exposed 60-day-old periphytic biofilms to 3 mg/L of pure glyphosate in microcosm experiments. After a colonization period of 60 d, biofilms developed a sufficiently consolidated matrix, limiting contact between the organisms and glyphosate.…”

Section: Glyphosate Is a Source Of Phosphorus But Not In A Bioavailabsupporting

confidence: 74%

“…At more mature colonization stages, microscopic ecological niches are created and nutrient exchanges with the water column decrease (Wetzel 1993;Hagerthey et al 2011). In mature biofilms, communities are, therefore, more protected from external stressors (Tlili et al 2011;Lozano et al 2018). This protection can be explained by the fact that as colonization proceeds, the production of extracellular polymeric substances (EPS) by algae and bacteria, including polysaccharides, might increase, forming a barrier to the surrounding water (Ivorra et al 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Studies have also shown that some pesticides and metals can alter the function and composition of periphytic communities, based on the assumption that, within biofilms, different species show distinct levels of sensitivity to these contaminants (Schmitt-Jansen and Altenburger 2005;Tlili et al 2010;Lavoie et al 2012). Even if some studies have assessed the effects of glyphosate on periphytic biofilms (Pérez et al 2007;Vera et al 2010;Vera et al 2014; FACETS | 2018 | 3: 934-951 | DOI: 10.1139/facets-2018-0019 935 facetsjournal.com Lozano et al 2018), its impact on community composition has mainly been evaluated through microscopic techniques (Pérez et al 2007;Vera et al 2010;Lozano et al 2018;Smedbol et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Age matters: Submersion period shapes community composition of lake biofilms under glyphosate stress

Khadra

Planas

Girard

et al. 2018

FACETS

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The phosphonate herbicide glyphosate, which is the active ingredient in the commercial formulation Roundup®, is currently the most globally used herbicide. In aquatic ecosystems, periphytic biofilms, or periphyton, are at the base of food webs and are often the first communities to be in direct contact with runoff. Microcosm experiments were conducted to assess the effects of a pulse exposure of glyphosate on community composition and chlorophyll a concentrations of lake biofilms at different colonization stages (2 months, 1 year, and 20 years). This is the first study that uses such contrasting submersion periods. Biofilms were exposed to either environmental levels of pure analytical grade glyphosate (6 μg/L, 65 μg/L, and 600 μg/L) or to corresponding phosphorus concentrations. Community composition was determined by deep sequencing of the 18S and 16S rRNA genes to target eukaryotes and cyanobacteria, respectively. The results showed that submersion period was the only significant contributor to community structure. However, at the taxon level, the potentially toxic genus Anabaena was found to increase in relative abundance. We also observed that glyphosate releases phosphorus into the surrounding water, but not in a bioavailable form. The results of this study indicate that environmental concentrations of glyphosate do not seem to impact the community composition or metabolism of lake biofilms under pulse event conditions.

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Section: Glyphosate Is a Source Of Phosphorus But Not In A Bioavailabsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Age matters: Submersion period shapes community composition of lake biofilms under glyphosate stress

Khadra

Planas

Girard

et al. 2018

FACETS

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“…Khadra et al (2018) investigated periphytic biofilms differing in age (at least 2 months) and exposed to different glyphosate concentrations (35.4, 383.5, and 3540 nM) in a lake. They concluded that glyphosate had no effect on biofilms, a finding also reported by Lozano et al (2018), who showed that periphyton was more resistant than phytoplankton to 17.7 µM glyphosate. Although the latter study did not find a biomass-based effect on periphyton, the abundance of certain taxa decreased.…”

Section: Potential Impacts Of Glyphosate On a Brackish Microbial Ecosmentioning

confidence: 62%

A Glyphosate Pulse to Brackish Long-Term Microcosms Has a Greater Impact on the Microbial Diversity and Abundance of Planktonic Than of Biofilm Assemblages

et al. 2019

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The widespread herbicide glyphosate has been detected in aquatic coastal zones of the southern Baltic Sea. We monitored community dynamics in glyphosateimpacted chemostats for 20 weeks to evaluate the potential impact of the herbicide on free-living and biofilm-associated bacterial community assemblages in a brackish ecosystem. A HPLC-MS/MS method was developed to measure glyphosate, aminomethylphosphonic acid and sarcosine concentrations within a brackish matrix. These concentrations were analyzed weekly, together with prokaryotic succession, determined by total cell counts and next generation 16S rRNA (gene) amplicon sequencing. Shotgun metagenomics provided insights into the glyphosate degradation potential of the microbial communities. Temporal increases in total cell counts, bacterial diversity and the abundances of distinct bacterial operational taxonomic units were identified in the water column. Biofilm communities proved to be less affected than pelagic ones, but their responses were of longer duration. The increase of glyphosate oxidoreductase (gox) and thiO gene as well as the phn operon abundance indicated glyphosate degradation by first the aminomethylphosphonic acid pathway and possibly a subsequent cleavage of the C-P bond. However, although glyphosate concentrations were reduced by 99%, 1 µM of the herbicide remained until the end of the experiment. Thus, when present at low concentrations, glyphosate may evade bacterial degradation and persist in Baltic Sea waters.

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“…2018). Other studies reported the effect of pure 2,4-D on microbial communities (Kobraei and White, 1996; Aguayo et al., 2014; Lozano et al., 2018), but little is known about the collateral impact of commercial formulations of this herbicide on wild biota in agricultural landscapes. These commercial formulations consist of the active ingredient (2,4-D), water and inert elements such as solvents, surfactants and humectants of unknown composition which increase plant cuticle permeability to 2,4-D (Lanctôt et al., 2014).…”

Section: Introductionmentioning

confidence: 99%

Turbidity matters: differential effect of a 2,4-D formulation on the structure of microbial communities from clear and turbid freshwater systems

Lozano

Miranda

Vinocur

et al. 2019

Heliyon

Self Cite

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We evaluated the effect of AsiMax 50®, a commercial formulation of 2,4-D (2,4-dichlorophenoxyacetic acid), on the structure of both micro + nano phytoplankton (>2 μm; species composition and abundance) and cytometric populations (photosynthetic picoplankton (PPP, 0.2–2 μm), which included prokaryotic phycocyanin-rich picocyanobacteria (PC-Pcy), phycoerythrin-rich picocyanobacteria (PE-Pcy) and eukaryotic phototrophs (PEuk); and bacterioplankton (HB), heterotrophic bacteria), using a microcosms-based approach and a single 7-day exposure. Assays were performed on two different microbial assemblages sampled from freshwater bodies of two contrasting turbidity status: clear (chlorophyll a = 7.6 μgL -1 , turbidity = 1 NTU) and organic turbid systems (chlorophyll a = 25.0 μgL -1 , turbidity = 9 NTU). For each system, the herbicide was applied to 500 mL-Erlenmeyer flasks, at seven concentration levels of the active ingredient (a.i.): 0 (control = no addition), 0.02, 0.2, 2, 20, 200 and 2,000 mg a.i.L −1 . The impact of AsiMax 50® seemed to be greater in the turbid system. In this system, total abundance of living (live) micro + nano phytoplankton showed a significant increase at lower concentrations and data were fitted to a humped-shaped curve. For both clear and organic turbid systems, micro + nano phytoplankton decreased in species richness and abundance at higher herbicide concentrations. These results suggest that 2,4-D may mimic hormonal function. Some species, such as Ochromonas sp. and Chlamydomonas sp., showed different responses to herbicide exposure between water systems. In the turbid system, the increase in abundance of the PPP fraction observed at 7-d exposure was probably due to either an increase in PE-Pcy (thus suggesting the existence of auxin pathways) or a reduction in competitive pressure by micro + nano plankton. Our results provide some evidence of the importance of using community-scale approaches in ecotoxicological studies to predict changes in freshwater ecosystems exposed to a 2,4-D-based formulation. However, caution must be taken when extrapolating these effects to real scenarios, as assays were based on a laboratory microcosm experiment.

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Effects of glyphosate and 2,4-D mixture on freshwater phytoplankton and periphyton communities: a microcosms approach

Cited by 48 publications

References 49 publications

Age matters: Submersion period shapes community composition of lake biofilms under glyphosate stress

Age matters: Submersion period shapes community composition of lake biofilms under glyphosate stress

A Glyphosate Pulse to Brackish Long-Term Microcosms Has a Greater Impact on the Microbial Diversity and Abundance of Planktonic Than of Biofilm Assemblages

Turbidity matters: differential effect of a 2,4-D formulation on the structure of microbial communities from clear and turbid freshwater systems

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