Effects of Photosystem Ii Inhibitors and Their Mixture on Freshwater Phytoplankton Succession in Outdoor Mesocosms

Knauert, Stefanie; Dawo, Ursula; Hollender, Juliane; Hommen, Udo; Knauer, Katja

doi:10.1897/08-135.1

Cited by 6 publications

(15 citation statements)

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“…The Shannon diversity index was similar in all mesocosms before treatment and then declined in controls but not in atrazine‐treated mesocosms. These results highlight the differences in community function and structure observations between unrealistic constantly high exposures and realistic pulsed exposures typical of second‐order and third‐order Midwestern streams as demonstrated in the present study.…”

Section: Discussionsupporting

confidence: 62%

“…Knauert et al evaluated the effects of atrazine (70 μg/L) on freshwater phytoplankton succession in outdoor mesocosms and found a significant reduction ( p < 0.05) in total phytoplankton abundance during 5 wk of constant exposure but no significant differences subsequent to day 40. With respect to community structure, atrazine‐treated mesocosms differed from controls on day 12 to day 40 and remained different from controls until the end of the observation period based on principal components analysis.…”

Section: Discussionmentioning

confidence: 99%

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Effects of pulsed atrazine exposures on autotrophic community structure, biomass, and production in field‐based stream mesocosms

King

Brain

Back

et al. 2016

Enviro Toxic and Chemistry

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Abstract:The authors performed a multiple-pulsed atrazine experiment to measure responses of autotrophic endpoints in outdoor stream mesocosms. The experiment was designed to synthetically simulate worst-case atrazine chemographs from streams in agricultural catchments to achieve 60-d mean concentrations of 0 mg/L (control), 10 mg/L, 20 mg/L, and 30 mg/L. The authors dosed triplicate streams with pulses of 0 mg/L, 50 mg/L, 100 mg/L, and 150 mg/L atrazine for 4 d, followed by 7 d without dosing. This 11-d cycle occurred 3 times, followed by a recovery (untreated) period from day 34 to day 60. Mean AE standard error 60-d atrazine concentrations were 0.07 AE 0.03 mg/L, 10.7 AE 0.05 mg/L, 20.9 AE 0.24 mg/L, and 31.0 AE 0.17 mg/L for the control, 10-mg/L, 20-mg/L, and 30-mg/L treatments, respectively. Multivariate analyses revealed that periphyton and phytoplankton community structure did not differ among treatments on any day of the experiment, including during the atrazine pulses. Control periphyton biomass in riffles was higher immediately following the peak of the first atrazine pulse and remained slightly higher than some of the atrazine treatments on most days through the peak of the last pulse. However, periphyton biomass was not different among treatments at the end of the present study. Phytoplankton biomass was not affected by atrazine. Metaphyton biomass in pools was higher in the controls near the midpoint of the present study and remained higher on most days for the remainder of the study. Ceratophyllum demersum, a submersed macrophyte, biomass was higher in controls than in 20-mg/L and 30-mg/L treatments before pulse 3 but was not different subsequent to pulse 3 through the end of the present study. Maximum daily dissolved oxygen (DO, percentage of saturation) declined during each pulse in approximate proportion to magnitude of dose but rapidly converged among treatments after the third pulse. However, DO increased in controls relative to all atrazine treatments during the last 17 d of the experiment, likely a result of metaphyton cover in the pools. Finally, atrazine significantly limited uptake of PO 4 3-and uptake and/or denitrification of NO 3 -but only during pulses; percentage of dose removed from the water column was >85% for P and >95% for N after pulse 3 through the end of the present study. Collectively, only DO and metaphyton biomass differed at the end of the present study and only slightly. Some other endpoints were affected but only during pulses, if at all. The high levels of primary production and accumulation of algal biomass in all streams suggest that effects of pulses of atrazine at the concentrations used in the present study appear transient and likely do not represent ecologically significant adverse outcomes to periphyton, phytoplankton, and aquatic macrophytes, particularly in agricultural streams subjected to high nutrient loads. Environ Toxicol Chem 2016;35:660-675. #

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Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Effects of pulsed atrazine exposures on autotrophic community structure, biomass, and production in field‐based stream mesocosms

King

Brain

Back

et al. 2016

Enviro Toxic and Chemistry

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“…For phytoplankton identification, sampling followed a similar procedure, with the exception that the collected water was poured through a stainless steel sieve of 55-mm pore size, stained, preserved with approximately 2 mL of Lugol-iodine solution [6], and stored in the dark before shipment to BSA Environmental Services for morphologic taxonomic identification. Samples were preserved with 90% ethanol, stored at room temperature in the dark, and stained with rose bengal (Fisher Scientific).…”

Section: Sampling Proceduresmentioning

confidence: 99%

“…Although there have been many studies investigating the effects of various chemical toxicants in seminatural experimental ecosystems such as mesocosms (e.g., Knauert et al [6]), information on effects on entire communities is lacking for the herbicides hexazinone and diuron in comparison with other pesticides; and these have rarely been studied as binary mixtures. However, knowledge about the effects of environmental factors on the sensitivity of entire communities and ecosystems remains scarce.…”

Section: Introductionmentioning

confidence: 99%

An assessment of direct and indirect effects of two herbicides on aquatic communities

Hasenbein

Lawler

Connon

2017

Enviro Toxic and Chemistry

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Herbicides are often detected in watersheds at concentrations that are toxic to phytoplankton, potentially causing indirect effects on higher trophic organisms. The long-term effects of 5 applications over 30 d of binary mixtures of the herbicides diuron and hexazinone were assessed at "low" and "high" concentrations typically found in the environment, using mesocosms. Sixteen of 95 phytoplankton taxa, 3 of 18 zooplankton taxa, and 6 of 14 macroinvertebrate taxa responded negatively to contaminant exposures. Herbicide applications altered the phytoplankton community structure. Relative abundance of Cyanophyceae decreased following 5 applications from 52.1% in the control to 37.3% in the low treatment and to 25.9% in the high treatment, while Chlorophyceae increased to 50.6% in the low treatment and to 61.7% in the high treatment compared with the control (39.7%). Chlorophyceae had the greatest number of affected species (8), whereas 1 species within the Cyanophyceae was negatively affected on more than 1 sampling day. Further, chlorophyll a was reduced on 4 and 5 d out of the 8 total sampling days in the low and high treatments, respectively, compared with the control. These results highlight that integrating multiple taxa and contaminants with long-term exposures in ecological risk assessments of herbicides can facilitate the ability to make predictive and mechanistic generalizations about the role of herbicides in shaping patterns of species abundance in natural systems. Environ Toxicol Chem 2017;36:2234-2244. © 2017 SETAC.

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“…Also, although it is possible to assess the effects of simple mixtures with this kind of approach by testing compounds individually, together with binary or ternary combinations (Pesce et al 2010b), it is practically impossible to consider all the combinations that can occur in complex mixtures such as those found in the environment. More generally, data on the impact of such mixtures is scant, especially when considering communitylevel effects (Van den Brink et al 2009;Pesce et al 2011b), and debate continues on the best way to deal with this issue (Knauert et al 2009). To address the problem of realistic mixtures, it has been suggested that passive sampling be combined with the assessment of extract toxicity via bioassays (Escher et al 2006;Bopp et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Effects of mixtures of dissolved and particulate contaminants on phototrophic biofilms: new insights from a PICT approach combining toxicity tests with passive samplers and model substances

Foulquier

Morin

Dabrin

et al. 2014

Environ Sci Pollut Res

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Streams located in vineyard areas are particularly exposed to mixtures of dissolved and particulate contaminants such as metals and organic pesticides. In this context, phototrophic biofilms are increasingly used as indicators of river water contaminations through pollution-induced community tolerance (PICT) assessments based on short-term toxicity tests with individual or mixtures of toxicants. We conducted a laboratory experiment to evaluate the relative influence of the dissolved and particulate fractions on the effects of metals and pesticides on phototrophic biofilms in a context of contamination from a vineyard watershed. Three sets of artificial channels were supplied with (i) unfiltered water from a stream reference site, (ii) unfiltered water from a stream contaminated site, and (iii) filtered water (0.45 μm) from the same contaminated site. Biofilm growth, diatom community structure, and dissolved toxicant concentrations differed slightly between channels supplied with unfiltered or filtered water from the contaminated site. However, PICT assessments with individual toxicants or mixtures of toxicants extracted from passive samplers suggested no significant difference in tolerance to metals and organic pesticides between phototrophic communities supplied with unfiltered or filtered contaminated water. Our results confirm the use of extracts from passive samplers as a promising approach in short-term toxicity tests to characterize impacts of contamination on aquatic communities.

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Effects of Photosystem Ii Inhibitors and Their Mixture on Freshwater Phytoplankton Succession in Outdoor Mesocosms

Cited by 6 publications

References 0 publications

Effects of pulsed atrazine exposures on autotrophic community structure, biomass, and production in field‐based stream mesocosms

Effects of pulsed atrazine exposures on autotrophic community structure, biomass, and production in field‐based stream mesocosms

An assessment of direct and indirect effects of two herbicides on aquatic communities

Effects of mixtures of dissolved and particulate contaminants on phototrophic biofilms: new insights from a PICT approach combining toxicity tests with passive samplers and model substances

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