1
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de Araujo GS, Ferreira ALG, da Maia Soares AMV, Abessa DMDS, Loureiro S. Multi-generation effects of lead (Pb) on two Daphnia species. ECOTOXICOLOGY (LONDON, ENGLAND) 2024:10.1007/s10646-024-02779-3. [PMID: 39003411 DOI: 10.1007/s10646-024-02779-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/01/2024] [Indexed: 07/15/2024]
Abstract
Two monophyletic Daphnia species (Daphnia magna and D. similis) were exposed to a sub-lethal concentration of Pb (50 µg/L) for nine generations under two food regimes (usual and restricted) and analyzed for acetylcholinesterase (AChE) activity, first reproduction delay, lifespan, and net reproductive rate (R0) at the subcellular, individual, and population levels, respectively. In the sixth generation, Pb-acclimated neonates were moved to clean media for three more generations to check for recovery. The net reproductive rate (R0) of D. magna was not affected by Pb. However, Pb stimulated reproduction, reduced lifespan, and decreased AChE activity. First reproduction delay and lifespan did not improve during the recovery process, suggesting a possible genetic adaptation. Food restriction reduced R0, lifespan, delayed hatching, and increased AChE activity; the opposite outcomes were observed for D. similis. The full recovery shown by R0 suggests the physiological acclimation of D. similis. Under food restriction, the animals exhibited a reduction of R0 and lifespan, delayed first reproduction, and increased AChE activity; however, there was no effect of Pb. The recovery process under food restriction showed that D. similis might not cope with Pb exposure, indicating a failed recovery. Such outcomes indicate that one model species' sensitivity may not represent another's sensitivity.
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Affiliation(s)
- Giuliana Seraphim de Araujo
- CESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Abel Luís Gonçalves Ferreira
- CESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, Aveiro, Portugal
| | | | | | - Susana Loureiro
- CESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, Aveiro, Portugal
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2
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Impacts of water hardness and road deicing salt on zooplankton survival and reproduction. Sci Rep 2023; 13:2975. [PMID: 36806739 PMCID: PMC9941116 DOI: 10.1038/s41598-023-30116-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/15/2023] [Indexed: 02/22/2023] Open
Abstract
Rising salinity from road deicing salts threatens the survival and reproduction of freshwater organisms. We conducted two experiments to address how Daphnia pulex survival and reproduction were affected by road salt concentration (control, 120, 640 and 1200 mg Cl-/L) crossed with three concentrations of water hardness (20, 97, 185 mg CaCO3 /L). D. pulex survival was poor in our hard water treatment in both experiments (185 mg CaCO3 /L), potentially indicating a low tolerance to hard water for the strain used in our experiments. With the remaining two hardness treatments (20 and 97 mg CaCO3 /L), we found no evidence of an interactive effect between salt concentration and water hardness on D. pulex survival. In our population-level experiment, D. pulex survival was reduced by > 60% at 120 mg Cl-/L compared to the control. In the individual experiment, survival was similar between the control and 120 mg Cl-/L, but ≤ 40% of individuals survived in 640 and 1200 mg Cl-/L. For the surviving individuals across all treatments, the number of offspring produced per individual declined with increasing Cl- concentration and in hard water. Our results indicate that current Cl- thresholds may not protect some zooplankton and reduced food availability per capita may enhance the negative impacts of road salt.
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3
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Huang J, Li Y, Sun Y, Zhang L, Lyu K, Yang Z. Size-specific sensitivity of cladocerans to freshwater salinization: Evidences from the changes in life history and population dynamics. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 296:118770. [PMID: 34974088 DOI: 10.1016/j.envpol.2021.118770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/24/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
The salinization of the global freshwater system caused by various human activities and climate change has become a common problem threatening freshwater biodiversity and resources, which may affect a variety of species of cladocerans at individual and population levels. In order to comprehensively evaluate the impact of salinization on different-sized cladocerans at individual and population levels, we exposed two species of cladocerans with obvious body size difference, Daphnia magna and Moina macrocopa, to seven salinities (0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12 M), recorded individual life history traits and population growth dynamics, and used multiple mechanistic models to fit the data. At the individual level, the median effect concentration of survival time, total offspring per female, and number of broods of D. magna were significantly higher than those of M. macrocopa. At the population level, the decrease in carrying capacity of D. magna with increasing salinity was significantly less than that of M. macrocopa. At the same salinity treatment, the integrated biomarker response indexes value of M. macrocopa is higher than that of D. magna. Therefore, it was further inferred that the sensitivity of small-sized species M. macrocopa to salinity stress is significantly higher than that of big-sized species D. magna. Thus, freshwater salinization may result in the replacement of smaller salt-intolerant cladocerans with larger salt-tolerant cladocerans, which may have dramatic effects on freshwater communities and ecosystems. Additionally, the increase of salinity had a greater impact on the population level of D. magna and M. macrocopa than on the individual level, indicating that population level of cladocerans was more susceptible to salinity stress. Experiments only based on individuals may underestimate the ecologically related changes in populations and communities, thus understanding the impact of salinization on freshwater systems needs to consider multiple ecological levels.
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Affiliation(s)
- Jing Huang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Yurou Li
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Yunfei Sun
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Lu Zhang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Kai Lyu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Zhou Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China.
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4
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Lowes HM, Snihur KN, Alessi DS, Clements JC, Blewett TA. Group versus individual exposure: Do methodological decisions in aquatic toxicology alter experimental results? THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 764:144288. [PMID: 33385645 DOI: 10.1016/j.scitotenv.2020.144288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/23/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
In aquatic toxicology, methods that are chosen for exposures have profound consequences on experimental outcomes and thus can skew policy initiatives. For example, as compared to single-organism exposures, toxicity test results of group exposures may be impacted by confounding factors such as social interactions between animals or individual variation in accumulation rates. To test for differences in organismal response between group and individual toxicological exposures, we exposed Daphnia magna to copper and subsequently compared the toxicity (median lethal concentration or LC50) between groups and individuals. Results suggested that water chemistry had a larger effect on experimental outcomes than the number of animals exposed in the same tank. Methodological decisions with respect to replication type can affect toxicity tests, and LC50s calculated using different exposure types (such as group and individual exposures) may not be comparable.
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Affiliation(s)
- Hannah M Lowes
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Katherine N Snihur
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel S Alessi
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jeff C Clements
- Fisheries and Oceans Canada, Gulf Fisheries Centre, Moncton, New Brunswick, Canada
| | - Tamzin A Blewett
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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5
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Woo TJ, East A, Salice CJ. Intraspecific interactions affect outcomes of pulse toxicity at different Daphnia magna population phases. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115398. [PMID: 33254684 DOI: 10.1016/j.envpol.2020.115398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 06/12/2023]
Abstract
Traditional toxicity tests assess stressor effects on individuals, while protection goals are focused on the population-level and above. Additionally, these tests ignore common ecological factors such as resource levels and population growth phase. The objective of this research was to explore effects of - and interactions between - resource availability and stress response at the individual and population levels using Daphnia magna as a model. We hypothesized that density-dependent changes in resources at various phases of population growth would cause different population responses to the same toxicant stress. Laboratory populations of Daphnia magna were exposed to a 48-h pulse of 20 or 30 μg/l pyraclostrobin in one of four distinct phases of laboratory population cycles: growth, peak, decline, and stable. Population size and recovery were observed throughout the 51-day study. Populations exposed to pyraclostrobin during the growth phase had the least mortality and fastest recovery, while populations in the peak phase had the greatest mortality and slowest recovery. These data suggested that high density and low food at the peak phase resulted in more sensitive daphnids. To further test this hypothesis, a resource-amended acute toxicity study was conducted to quantify the effects of food resource on pyraclostrobin toxicity to Daphnia magna. Three age classes of Daphnia magna (neonate, subadult, adult) were fed low or high food levels and exposed to pyraclostrobin for 48 h. Toxicity was greater, as shown by lower 48 h LC50s, for smaller Daphnia magna age classes and lower food levels comporting results in the population study. Importantly, the acute toxicity studies generally yielded lower effect levels than the population studies suggesting that while the standard acute studies are ecologically unrealistic, they may be protective of toxicity under some circumstances. Collectively, these data point to the importance of population phase and the resource environment in modulating toxicity.
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Affiliation(s)
- Timothy J Woo
- Environmental Science and Studies Program, Towson University, 8000 York Rd., Towson, MD, 21252, USA
| | - Andrew East
- Environmental Science and Studies Program, Towson University, 8000 York Rd., Towson, MD, 21252, USA
| | - Christopher J Salice
- Environmental Science and Studies Program & Department of Biological Sciences, Towson University, 8000 York Rd, Towson, MD, 21252, USA.
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6
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Baillard V, Sulmon C, Bittebiere AK, Mony C, Couée I, Gouesbet G, Delignette-Muller ML, Devin S, Billoir E. Effect of interspecific competition on species sensitivity distribution models: Analysis of plant responses to chemical stress. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 200:110722. [PMID: 32460047 DOI: 10.1016/j.ecoenv.2020.110722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 05/05/2020] [Accepted: 05/11/2020] [Indexed: 06/11/2023]
Abstract
Species Sensitivity Distributions (SSD) are widely used in environmental risk assessment to predict the concentration of a contaminant that is hazardous for 5% of species (HC5). They are based on monospecific bioassays conducted in the laboratory and thus do not directly take into account ecological interactions. This point, among others, is accounted for in environmental risk assessment through an assessment factor (AF) that is applied to compensate for the lack of environmental representativity. In this study, we aimed to assess the effects of interspecific competition on the responses towards isoproturon of plant species representative of a vegetated filter strip community, and to assess its impact on the derived SSD and HC5 values. To do so, we realized bioassays confronting six herbaceous species to a gradient of isoproturon exposure in presence and absence of a competitor. Several modelling approaches were applied to see how they affected the results, using different critical effect concentrations and investigating different ways to handle multiple endpoints in SSD. At the species level, there was a strong trend toward organisms being more sensitive to isoproturon in presence of a competitor than in its absence. At the community level, this trend was also observed in the SSDs and HC5 values were always lower in presence of a competitor (1.12-11.13 times lower, depending on the modelling approach). Our discussion questions the relevance of SSD and AF as currently applied in environmental risk assessment.
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Affiliation(s)
| | - Cécile Sulmon
- Univ Rennes, CNRS, Ecobio [(Ecosystèmes, Biodiversité, Évolution)] - Umr 6553, F-35000, Rennes, France
| | - Anne-Kristel Bittebiere
- Université de Lyon 1, CNRS, UMR 5023 LEHNA, 43 Boulevard Du 11 Novembre 1918, Villeurbanne, Cedex, 69622, France
| | - Cendrine Mony
- Univ Rennes, CNRS, Ecobio [(Ecosystèmes, Biodiversité, Évolution)] - Umr 6553, F-35000, Rennes, France
| | - Ivan Couée
- Univ Rennes, CNRS, Ecobio [(Ecosystèmes, Biodiversité, Évolution)] - Umr 6553, F-35000, Rennes, France
| | - Gwenola Gouesbet
- Univ Rennes, CNRS, Ecobio [(Ecosystèmes, Biodiversité, Évolution)] - Umr 6553, F-35000, Rennes, France
| | - Marie Laure Delignette-Muller
- Université de Lyon, Université Lyon 1, CNRS, VetAgro Sup, UMR 5558, Laboratoire de Biométrie et Biologie Evolutive, 69622, Villeurbanne, France
| | - Simon Devin
- Université de Lorraine, CNRS, LIEC, F-57000 Metz, France
| | - Elise Billoir
- Université de Lorraine, CNRS, LIEC, F-57000 Metz, France
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7
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Krewski D, Andersen ME, Tyshenko MG, Krishnan K, Hartung T, Boekelheide K, Wambaugh JF, Jones D, Whelan M, Thomas R, Yauk C, Barton-Maclaren T, Cote I. Toxicity testing in the 21st century: progress in the past decade and future perspectives. Arch Toxicol 2019; 94:1-58. [DOI: 10.1007/s00204-019-02613-4] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 11/05/2019] [Indexed: 12/19/2022]
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8
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Gust KA, Kennedy AJ, Laird JG, Wilbanks MS, Barker ND, Guan X, Melby NL, Burgoon LD, Kjelland ME, Swannack TM. Different as night and day: Behavioural and life history responses to varied photoperiods in Daphnia magna. Mol Ecol 2019; 28:4422-4438. [PMID: 31486145 PMCID: PMC6856852 DOI: 10.1111/mec.15230] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/08/2019] [Accepted: 08/28/2019] [Indexed: 01/18/2023]
Abstract
Nearly all animal species have utilized photoperiod to cue seasonal behaviours and life history traits. We investigated photoperiod responses in keystone species, Daphnia magna, to identify molecular processes underlying ecologically important behaviours and traits using functional transcriptomic analyses. Daphnia magna were photoperiod‐entrained immediately posthatch to a standard control photoperiod of 16 light/ 8 dark hours (16L:8D) relative to shorter (4L:20D, 8L:16D, 12L:12L) and longer (20L:4D) day length photoperiods. Short‐day photoperiods induced significantly increased light‐avoidance behaviours relative to controls. Correspondingly, significant differential transcript expression for genes involved in glutamate signalling was observed, a critical signalling pathway in arthropod light‐avoidance behaviour. Additionally, period circadian protein and proteins coding F‐box/LRR‐repeat domains were differentially expressed which are recognized to establish circadian rhythms in arthropods. Indicators of metabolic rate increased in short‐day photoperiods which corresponded with broadscale changes in transcriptional expression across system‐level energy metabolism pathways. The most striking observations included significantly decreased neonate production at the shortest day length photoperiod (4L:20D) and significantly increased male production across short‐day and equinox photoperiods (4L:20D, 8L:16D and 12L:12D). Transcriptional expression consistent with putative mechanisms of male production was observed including photoperiod‐dependent expression of transformer‐2 sex‐determining protein and small nuclear ribonucleoprotein particles (snRNPs) which control splice variant expression for genes like transformer. Finally, increased transcriptional expression of glutamate has also been shown to induce male production in Daphnia pulex via photoperiod‐sensitive mechanisms. Overall, photoperiod entrainment affected molecular pathways that underpin critical behavioural and life history traits in D. magna providing fundamental insights into biological responses to this primary environmental cue.
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Affiliation(s)
- Kurt A Gust
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Alan J Kennedy
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Jennifer G Laird
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Mitchell S Wilbanks
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | | | - Xin Guan
- Bennett Aerospace, Cary, NC, USA
| | - Nicolas L Melby
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Lyle D Burgoon
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Michael E Kjelland
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
| | - Todd M Swannack
- Environmental Laboratory, Engineer Research and Development Center, US Army, Vicksburg, MS, USA
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9
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Pereira CMS, Vlaeminck K, Viaene K, De Schamphelaere KAC. The Unexpected Absence of Nickel Effects on a Daphnia Population at 3 Temperatures is Correctly Predicted by a Dynamic Energy Budget Individual-Based Model. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:1423-1433. [PMID: 30883889 DOI: 10.1002/etc.4407] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 02/24/2019] [Accepted: 03/03/2019] [Indexed: 06/09/2023]
Abstract
Recent studies have shown that temperature affects chronic nickel (Ni) toxicity to Daphnia magna at the individual (apical) level. However, the effect of temperature on Ni toxicity to D. magna at the population level is unknown. The present study investigated whether the effect of temperature on chronic Ni toxicity to D. magna assessed on apical endpoints can be extrapolated to the population level. The results of the population experiment showed no consistent Ni effects on total D. magna population abundance at 15, 20, and 25 °C, although the Ni concentrations tested were previously reported to significantly reduce reproduction in D. magna individuals. This result supports the idea that ecological risk assessment should not extrapolate as such from apical endpoints to the population level. A dynamic energy budget individual-based model (DEB-IBM) was calibrated using apical Ni toxicity data at 15, 20, and 25 °C. The goal was to investigate whether the calibrated DEB-IBM would be able to predict the unexpected absence of effects at the population level and to further investigate the effect of temperature on Ni toxicity to a D. magna population. At the population level, the calibrated DEB-IBM correctly predicted the unexpected absence of an effect of Ni on a D. magna population. Detailed analysis of simulation output suggests that the predicted lower Ni sensitivity at the population level occurs because Ni-induced mortality is compensated by reduced starvation (less intraspecific competition). Extrapolated median effective concentration (EC50) values for population density predicted that the effect of temperature on Ni toxicity to D. magna populations was smaller (1.9-fold higher at 25 °C than at 15 °C) than on Ni toxicity to D. magna apical reproduction (the EC50 is 6.5-fold higher at 25 °C than at 15 °C). These results show that the DEB-IBM can help to replace population experiments by in silico simulations and to optimize the experimental design of population studies. Environ Toxicol Chem 2019;38:1423-1433. © 2019 SETAC.
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Affiliation(s)
- Cecília M S Pereira
- Laboratory of Environmental Toxicology and Aquatic Ecology, Environmental Toxicology Unit (GhEnToxLab), Ghent University, Ghent, Belgium
- Laboratory for Systemic Physiology and Ecotoxicological Research, University of Antwerp, Antwerp, Belgium
| | - Karel Vlaeminck
- Laboratory of Environmental Toxicology and Aquatic Ecology, Environmental Toxicology Unit (GhEnToxLab), Ghent University, Ghent, Belgium
- ARCHE (Assessing Risks of Chemicals) Consulting, Ghent (Wondelgem), Belgium
| | - Karel Viaene
- ARCHE (Assessing Risks of Chemicals) Consulting, Ghent (Wondelgem), Belgium
| | - Karel A C De Schamphelaere
- Laboratory of Environmental Toxicology and Aquatic Ecology, Environmental Toxicology Unit (GhEnToxLab), Ghent University, Ghent, Belgium
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10
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Bruijning M, Berge ACM, Jongejans E. Population‐level responses to temperature, density and clonal differences in
Daphnia magna
as revealed by integral projection modelling. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13192] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Marjolein Bruijning
- Department of Animal Ecology and Physiology Radboud University Nijmegen The Netherlands
| | - Anne C. M. Berge
- Department of Animal Ecology and Physiology Radboud University Nijmegen The Netherlands
| | - Eelke Jongejans
- Department of Animal Ecology and Physiology Radboud University Nijmegen The Netherlands
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11
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Grintzalis K, Dai W, Panagiotidis K, Belavgeni A, Viant MR. Miniaturising acute toxicity and feeding rate measurements in Daphnia magna. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2017; 139:352-357. [PMID: 28189099 DOI: 10.1016/j.ecoenv.2017.02.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/30/2017] [Accepted: 02/05/2017] [Indexed: 05/27/2023]
Abstract
Phenotypic markers of animal health form an essential component of regulatory toxicology. Immobilisation of neonate water fleas - Daphnia magna - as a surrogate measure of their mortality following exposure to a chemical for 24-48h forms the basis of the internationally utilised OECD acute toxicity test 202. A second important marker of animal physiology and health is feeding rate, which in Daphnia is determined by measuring the algae feeding rate. Given the widespread use of OECD test 202 for acute toxicity as well as the quantification of feeding rate in toxicological studies of daphniids, significant benefits could result from miniaturising this assay. In particular, miniaturisation would use fewer animals, less media and chemicals, less laboratory space and make the tests more compatible with automation, and therefore could result in considerable time savings. Furthermore, miniaturising phenotypic markers to the ultimate level of a single animal per well would facilitate multiple measurements of other phenotypic markers, such as behavioural responses, which could be integrated at the individual level. In this study we used a wide range of exposure vessels to evaluate the impacts of systematically varying total media volume, surface to volume ratio and animal density for the acute toxicity testing of cadmium. We demonstrate that Daphnia acute toxicity tests using single animals within 24- or 48-well plates produce equivalent results as for traditional test configurations, for different chemicals. Considering algae feeding rates by Daphnia, we studied the impacts of varying algae concentration, total volume and animal density. After having demonstrated that multiwell plates can again yield equivalent test results as traditional experimental setups, we used miniaturised test vessels to show the impact of metals on the feeding activity on daphniids for both neonates and adult animals. Overall we confirm the feasibility of a multiwell approach for Daphnia toxicity testing that requires less time and materials than a traditional assay and can provide phenotypic characterisation at a single animal level.
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Affiliation(s)
| | - Wenkui Dai
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Konstantinos Panagiotidis
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; Department of Biology, Section of Animal Biology, School of Natural Sciences, University of Patras, Patras 26500, Greece
| | - Alexia Belavgeni
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; Department of Biology, Section of Animal Biology, School of Natural Sciences, University of Patras, Patras 26500, Greece
| | - Mark R Viant
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
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