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Romero-Blanco A, Alonso Á. Laboratory versus wild populations: the importance of population origin in aquatic ecotoxicology. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:22798-22808. [PMID: 35041167 DOI: 10.1007/s11356-021-17370-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/29/2021] [Indexed: 06/14/2023]
Abstract
The origin of the populations used in ecotoxicological bioassays (from nature (wild populations) or from cultures (laboratory populations)) could have a key influence on the sensitivity of the tested species to different toxicants. However, the available information on this subject is scarce. To assess the likely influence of the population origin (wild vs. laboratory) of species-genus on the toxicant tolerance, we performed a quantitative review of the ECOTOX database, from which we collected the effective concentrations for a wide range of compounds (metals and organics), endpoints, and exposure times. We found a general trend of lower sensitivity of wild populations to toxicants than laboratory populations, although sensitivity was dependent on species and toxicant groups. This suggests that the results of bioassays with laboratory populations may overestimate the toxicity of most of the compounds. Our study highlights the relevance of the origin of the populations in the determination of the sensitivity of species to toxicants. This study also warns about the biases in the species and toxicants used in ecotoxicology, which may lead to an underrepresentation of the biodiversity and the toxicological context of aquatic ecosystems.
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Affiliation(s)
- Alberto Romero-Blanco
- Facultad de Ciencias, Departamento de Ciencias de La Vida, Unidad de Ecología, Biological Invasions Research Group, Universidad de Alcalá, Plaza de San Diego S/N, 28805, Alcalá de Henares, Madrid, Spain.
| | - Álvaro Alonso
- Facultad de Ciencias, Departamento de Ciencias de La Vida, Unidad de Ecología, Biological Invasions Research Group, Universidad de Alcalá, Plaza de San Diego S/N, 28805, Alcalá de Henares, Madrid, Spain
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2
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Brigante J, Costa JO, Espíndola ELG, Daam MA. Acute toxicity of the insecticide abamectin and the fungicide difenoconazole (individually and in mixture) to the tropical stingless bee Melipona scutellaris. ECOTOXICOLOGY (LONDON, ENGLAND) 2021; 30:1872-1879. [PMID: 34379243 DOI: 10.1007/s10646-021-02458-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Stingless bees have been recognized as essential plant pollinators and producers of various natural products in neotropical areas. Research into the potential risks of pesticides they may be exposed to in agricultural fields, however, remains meagre. Especially the toxicity of pesticide mixtures likely to occur under real-world conditions and that are likely to exert synergetic effects has been poorly studied. The aim of the present study was therefore to evaluate the single and mixture acute contact and oral toxicity of commercial products containing the insecticide abamectin and the fungicide difenoconazole in laboratory bioassays with the Brazilian native stingless bee Melipona scutellaris. In addition, a comparison of the insecticide sensitivity of stingless bees relative to the honeybee Apis mellifera was made based on previously published toxicity data. Except for oral exposure to abamectin, M. scutellaris appeared to be more sensitive that A. mellifera in the single compound toxicity tests. A difenoconazole concentration at the NOEC (no observed effect concentration) level indicated a synergetic toxic interaction with abamectin. A sensitivity comparison based on published toxicity data for A. mellifera and stingless bees indicated several insecticidal modes of action having a high relative sensitivity to stingless bees that need especial consideration in future studies. The research findings highlight the need for testing native bee species and environmentally relevant pesticide mixtures in risk assessments to avoid underestimation of potential risks to bee populations and the subsequent loss of pollination ecosystem services.
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Affiliation(s)
- Janete Brigante
- NEEA/CRHEA/SHS, São Carlos Engineering School, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, 13.560-970, Brazil
| | - Joyce Oliveira Costa
- NEEA/CRHEA/SHS, São Carlos Engineering School, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, 13.560-970, Brazil
| | - Evaldo L G Espíndola
- NEEA/CRHEA/SHS, São Carlos Engineering School, University of São Paulo, Av. Trabalhador São Carlense, 400, São Carlos, 13.560-970, Brazil
| | - Michiel A Daam
- CENSE, Department of Environmental Sciences and Engineering, Faculty of Sciences and Technology, New University of Lisbon, Quinta da Torre, 2829-516, Caparica, Portugal.
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3
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Becker JM, Ganatra AA, Kandie F, Mühlbauer L, Ahlheim J, Brack W, Torto B, Agola EL, McOdimba F, Hollert H, Fillinger U, Liess M. Pesticide pollution in freshwater paves the way for schistosomiasis transmission. Sci Rep 2020; 10:3650. [PMID: 32107456 PMCID: PMC7046736 DOI: 10.1038/s41598-020-60654-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 02/14/2020] [Indexed: 12/19/2022] Open
Abstract
Schistosomiasis is a severe neglected tropical disease caused by trematodes and transmitted by freshwater snails. Snails are known to be highly tolerant to agricultural pesticides. However, little attention has been paid to the ecological consequences of pesticide pollution in areas endemic for schistosomiasis, where people live in close contact with non-sanitized freshwaters. In complementary laboratory and field studies on Kenyan inland areas along Lake Victoria, we show that pesticide pollution is a major driver in increasing the occurrence of host snails and thus the risk of schistosomiasis transmission. In the laboratory, snails showed higher insecticide tolerance to commonly found pesticides than associated invertebrates, in particular to the neonicotinoid Imidacloprid and the organophosphate Diazinon. In the field, we demonstrated at 48 sites that snails were present exclusively in habitats characterized by pesticide pollution and eutrophication. Our analysis revealed that insensitive snails dominated over their less tolerant competitors. The study shows for the first time that in the field, pesticide concentrations considered “safe” in environmental risk assessment have indirect effects on human health. Thus we conclude there is a need for rethinking the environmental risk of low pesticide concentrations and of integrating agricultural mitigation measures in the control of schistosomiasis.
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Affiliation(s)
- Jeremias M Becker
- Helmholtz Centre for Environmental Research - UFZ, Department System-Ecotoxicology, Permoserstrasse 15, 04318, Leipzig, Germany.,RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research, Worringerweg 1, 52074, Aachen, Germany
| | - Akbar A Ganatra
- International Centre of Insect Physiology and Ecology (icipe), Human Health department, P.O. Box 30772-00100, Nairobi, Kenya. .,Egerton University, Biological sciences, P.O Box 536-20115, Njoro, Kenya.
| | - Faith Kandie
- RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research, Worringerweg 1, 52074, Aachen, Germany.,International Centre of Insect Physiology and Ecology (icipe), Human Health department, P.O. Box 30772-00100, Nairobi, Kenya
| | - Lina Mühlbauer
- Helmholtz Centre for Environmental Research - UFZ, Department System-Ecotoxicology, Permoserstrasse 15, 04318, Leipzig, Germany.,Ruprecht-Karl-University of Heidelberg, Faculty of Biosciences, Im Neuenheimer Feld 234, 69120, Heidelberg, Germany
| | - Jörg Ahlheim
- Helmholtz Centre for Environmental Research - UFZ, Department System-Ecotoxicology, Permoserstrasse 15, 04318, Leipzig, Germany
| | - Werner Brack
- Helmholtz Centre for Environmental Research - UFZ, Department System-Ecotoxicology, Permoserstrasse 15, 04318, Leipzig, Germany.,RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research, Worringerweg 1, 52074, Aachen, Germany
| | - Baldwyn Torto
- International Centre of Insect Physiology and Ecology (icipe), Human Health department, P.O. Box 30772-00100, Nairobi, Kenya
| | - Eric L Agola
- Centre for Biotechnology Research and Development, Kenya Medical Research institute (KEMRI), P.O. Box 54840-00200, Nairobi, Kenya.,The Technical University of Kenya, P.O. Box 52428-00200, Nairobi, Kenya
| | - Francis McOdimba
- International Centre of Insect Physiology and Ecology (icipe), Human Health department, P.O. Box 30772-00100, Nairobi, Kenya.,Egerton University, Biological sciences, P.O Box 536-20115, Njoro, Kenya
| | - Henner Hollert
- RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research, Worringerweg 1, 52074, Aachen, Germany.,Department Evolutionary Ecology and Environmental Toxicology, Institute of Ecology, Evolution and Diversity, Faculty Biological Sciences, Goethe University Frankfurt, Frankfurt, 60438, Germany
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (icipe), Human Health department, P.O. Box 30772-00100, Nairobi, Kenya.
| | - Matthias Liess
- Helmholtz Centre for Environmental Research - UFZ, Department System-Ecotoxicology, Permoserstrasse 15, 04318, Leipzig, Germany. .,RWTH Aachen University, Department of Ecosystem Analysis, Institute for Environmental Research, Worringerweg 1, 52074, Aachen, Germany.
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Alric B, Geffard O, Chandesris A, Ferréol M, François A, Perceval O, Piffady J, Villeneuve B, Chaumot A. Multisubstance Indicators Based on Caged Gammarus Bioaccumulation Reveal the Influence of Chemical Contamination on Stream Macroinvertebrate Abundances across France. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5906-5915. [PMID: 31046249 DOI: 10.1021/acs.est.9b01271] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Most anthropogenic stressors affecting freshwater systems are qualitatively known. However, the quantitative assessment of contaminant exposure and effects to aquatic communities is still difficult, limiting the understanding of consequences on aquatic ecosystem functioning and the implementation of effective management plans. Here, multisubstance indicators based on caged gammarid bioaccumulated contamination data are proposed (for metals and persistent organic pollutants, POPs) to map the bioavailable contamination level of freshwater ecosystems at a large spatial scale. We assessed the ability of these indicators to highlight the relationships between chemical exposure gradients and alteration in the abundance of macroinvertebrate populations on a data set of 218 watercourses distributed throughout France. We identified spatial regional heterogeneities in the levels of bioavailable contamination of metals (18 compounds) and POPs (43 compounds). Besides this, a degradation of Gammaridae, Ephemeridae, and Hydrobiidae densities with increasing levels of metal contamination are identified relative to Baetidae, Chironomidae, and Hydropsychidae. We show here that active biomonitoring allows the establishment of multisubstance indicators of bioavailable contamination, which reliably quantify chemical exposure gradients in freshwater ecosystems. Our ability to identify species-specific responses to chemical exposure gradients demonstrates the promising possibility to further decipher the effects of chemical contamination on macroinvertebrate assemblages through this type of indicator.
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Affiliation(s)
| | | | | | | | | | - Olivier Perceval
- Agence Française Pour La Biodiversité , site de Vincennes, 5 Square Felix Nadar , 94300 Vincennes , France
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5
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Gerner NV, Cailleaud K, Bassères A, Liess M, Beketov MA. Sensitivity ranking for freshwater invertebrates towards hydrocarbon contaminants. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:1216-1226. [PMID: 28879485 DOI: 10.1007/s10646-017-1847-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/16/2017] [Indexed: 06/07/2023]
Abstract
Hydrocarbons have an utmost economical importance but may also cause substantial ecological impacts due to accidents or inadequate transportation and use. Currently, freshwater biomonitoring methods lack an indicator that can unequivocally reflect the impacts caused by hydrocarbons while being independent from effects of other stressors. The aim of the present study was to develop a sensitivity ranking for freshwater invertebrates towards hydrocarbon contaminants, which can be used in hydrocarbon-specific bioindicators. We employed the Relative Sensitivity method and developed the sensitivity ranking S hydrocarbons based on literature ecotoxicological data supplemented with rapid and mesocosm test results. A first validation of the sensitivity ranking based on an earlier field study has been conducted and revealed the S hydrocarbons ranking to be promising for application in sensitivity based indicators. Thus, the first results indicate that the ranking can serve as the core component of future hydrocarbon-specific and sensitivity trait based bioindicators.
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Affiliation(s)
- Nadine V Gerner
- Department System-Ecotoxicology, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, Leipzig, 04318, Germany.
- Quantitative Landscape Ecology, Institute for Environmental Science, University of Koblenz-Landau, Fortstraße 7, Landau, 76829, Germany.
- Emschergenossenschaft/Lippeverband, Kronprinzenstraße 24, Essen, 45128, Germany.
| | - Kevin Cailleaud
- TOTAL SA, PERL-Service Environment, RN 117-BP 47, Lacq, 64170, France
| | - Anne Bassères
- TOTAL SA, PERL-Service Environment, RN 117-BP 47, Lacq, 64170, France
| | - Matthias Liess
- Department System-Ecotoxicology, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, Leipzig, 04318, Germany
- RWTH Aachen University, Institute for Environmental Research (Biology V), Worringer Weg 1, Aachen, 52074, Germany
| | - Mikhail A Beketov
- Department System-Ecotoxicology, UFZ-Helmholtz Centre for Environmental Research, Permoserstraße 15, Leipzig, 04318, Germany
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6
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Debecker S, Dinh KV, Stoks R. Strong Delayed Interactive Effects of Metal Exposure and Warming: Latitude-Dependent Synergisms Persist Across Metamorphosis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:2409-2417. [PMID: 28146353 DOI: 10.1021/acs.est.6b04989] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
As contaminants are often more toxic at higher temperatures, predicting their impact under global warming remains a key challenge for ecological risk assessment. Ignoring delayed effects, synergistic interactions between contaminants and warming, and differences in sensitivity across species' ranges could lead to an important underestimation of the risks. We addressed all three mechanisms by studying effects of larval exposure to zinc and warming before, during, and after metamorphosis in Ischnura elegans damselflies from high- and low-latitude populations. By integrating these mechanisms into a single study, we could identify two novel patterns. First, during exposure zinc did not affect survival, whereas it induced mild to moderate postexposure mortality in the larval stage and at metamorphosis, and very strongly reduced adult lifespan. This severe delayed effect across metamorphosis was especially remarkable in high-latitude animals, as they appeared almost insensitive to zinc during the larval stage. Second, the well-known synergism between metals and warming was manifested not only during the larval stage but also after metamorphosis, yet notably only in low-latitude damselflies. These results highlight that a more complete life-cycle approach that incorporates the possibility of delayed interactions between contaminants and warming in a geographical context is crucial for a more realistic risk assessment in a warming world.
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Affiliation(s)
- Sara Debecker
- Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven/University of Leuven , Charles Deberiotstraat 32 bus 2439, 3000 Leuven, Belgium
| | - Khuong V Dinh
- Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven/University of Leuven , Charles Deberiotstraat 32 bus 2439, 3000 Leuven, Belgium
- National Institute of Aquatic Resources, Technical University of Denmark , Jægersborg Alle 1D, Charlottenlund 2920, Denmark
- Department of Freshwater Aquaculture, Institute of Aquaculture, Nha Trang University , No 2 Nguyen Dinh Chieu, Nha Trang, 650000, Vietnam
| | - Robby Stoks
- Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven/University of Leuven , Charles Deberiotstraat 32 bus 2439, 3000 Leuven, Belgium
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7
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Augusiak J, Van den Brink PJ. The influence of insecticide exposure and environmental stimuli on the movement behaviour and dispersal of a freshwater isopod. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1338-1352. [PMID: 27307165 PMCID: PMC4961728 DOI: 10.1007/s10646-016-1686-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 06/06/2016] [Indexed: 06/06/2023]
Abstract
Behaviour links physiological function with ecological processes and can be very sensitive towards environmental stimuli and chemical exposure. As such, behavioural indicators of toxicity are well suited for assessing impacts of pesticides at sublethal concentrations found in the environment. Recent developments in video-tracking technologies offer the possibility of quantifying behavioural patterns, particularly locomotion, which in general has not been studied and understood very well for aquatic macroinvertebrates to date. In this study, we aim to determine the potential effects of exposure to two neurotoxic pesticides with different modes of action at different concentrations (chlorpyrifos and imidacloprid) on the locomotion behaviour of the water louse Asellus aquaticus. We compare the effects of the different exposure regimes on the behaviour of Asellus with the effects that the presence of food and shelter exhibit to estimate the ecological relevance of behavioural changes. We found that sublethal pesticide exposure reduced dispersal distances compared to controls, whereby exposure to chlorpyrifos affected not only animal activity but also step lengths while imidacloprid only slightly affected step lengths. The presence of natural cues such as food or shelter induced only minor changes in behaviour, which hardly translated to changes in dispersal potential. These findings illustrate that behaviour can serve as a sensitive endpoint in toxicity assessments. However, under natural conditions, depending on the exposure concentration, the actual impacts might be outweighed by environmental conditions that an organism is subjected to. It is, therefore, of importance that the assessment of toxicity on behaviour is done under relevant environmental conditions.
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Affiliation(s)
- Jacqueline Augusiak
- Aquatic Ecology and Water Quality Management Group, Wageningen University and Research centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
| | - Paul J Van den Brink
- Aquatic Ecology and Water Quality Management Group, Wageningen University and Research centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands
- Alterra, Wageningen University and Research centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands
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8
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Wiberg-Larsen P, Graeber D, Kristensen EA, Baattrup-Pedersen A, Friberg N, Rasmussen JJ. Trait Characteristics Determine Pyrethroid Sensitivity in Nonstandard Test Species of Freshwater Macroinvertebrates: A Reality Check. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:4971-4978. [PMID: 27082866 DOI: 10.1021/acs.est.6b00315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We exposed 34 species of stream macroinvertebrates, representing 29 families, to a 90 min pulse of the pyrethroid λ-cyhalothrin. For 28 of these species, no pyrethroid ecotoxicity data exist. We recorded mortality rates 6 days post-exposure, and the behavioral response to pyrethroid exposure was recorded using automated video tracking. Most arthropod species showed mortality responses to the exposure concentrations (0.01-10 μg L(-1)), whereas nonarthropod species remained unaffected. LC50 varied by at least a factor of 1000 among arthropod species, even within the same family. This variation could not be predicted using ecotoxicity data from closely related species, nor using species-specific indicator values from traditional ecological quality indices. Moreover, LC50 was not significantly correlated to effect thresholds for behavioral responses. Importantly, however, the measured surface area-weight ratio and the preference for coarse substrates significantly influenced the LC50 for arthropod species, with the combination of small individuals and strong preference for coarse substrates indicating higher pyrethroid sensitivity. Our study highlights that existing pesticide ecotoxicity data should be extrapolated to untested species with caution and that actual body size (not maximum potential body size, as is usually available in traits databases) and habitat preference are central parameters determining species sensitivities to pyrethroids.
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Affiliation(s)
- Peter Wiberg-Larsen
- Institute for Bioscience, Aarhus University , Vejlsoevej 25, DK-8600 Silkeborg, Denmark
| | - Daniel Graeber
- Institute for Bioscience, Aarhus University , Vejlsoevej 25, DK-8600 Silkeborg, Denmark
| | - Esben A Kristensen
- Institute for Bioscience, Aarhus University , Vejlsoevej 25, DK-8600 Silkeborg, Denmark
| | | | - Nikolai Friberg
- Institute for Bioscience, Aarhus University , Vejlsoevej 25, DK-8600 Silkeborg, Denmark
- NIVA, Section for Freshwater Biology , Gaustadalléen 21, NO-0349 Oslo, Norway
| | - Jes J Rasmussen
- Institute for Bioscience, Aarhus University , Vejlsoevej 25, DK-8600 Silkeborg, Denmark
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Ottermanns R, Szonn K, Preuß TG, Roß-Nickoll M. Non-linear analysis indicates chaotic dynamics and reduced resilience in model-based Daphnia populations exposed to environmental stress. PLoS One 2014; 9:e96270. [PMID: 24809537 PMCID: PMC4014494 DOI: 10.1371/journal.pone.0096270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 04/04/2014] [Indexed: 11/22/2022] Open
Abstract
In this study we present evidence that anthropogenic stressors can reduce the resilience of age-structured populations. Enhancement of disturbance in a model-based Daphnia population lead to a repression of chaotic population dynamics at the same time increasing the degree of synchrony between the population's age classes. Based on the theory of chaos-mediated survival an increased risk of extinction was revealed for this population exposed to high concentrations of a chemical stressor. The Lyapunov coefficient was supposed to be a useful indicator to detect disturbance thresholds leading to alterations in population dynamics. One possible explanation could be a discrete change in attractor orientation due to external disturbance. The statistical analysis of Lyapunov coefficient distribution is proposed as a methodology to test for significant non-linear effects of general disturbance on populations. Although many new questions arose, this study forms a theoretical basis for a dynamical definition of population recovery.
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Affiliation(s)
- Richard Ottermanns
- Institute for Environmental Research, RWTH Aachen University, Aachen, Germany
| | - Kerstin Szonn
- Institute for Environmental Research, RWTH Aachen University, Aachen, Germany
| | - Thomas G. Preuß
- Institute for Environmental Research, RWTH Aachen University, Aachen, Germany
| | - Martina Roß-Nickoll
- Institute for Environmental Research, RWTH Aachen University, Aachen, Germany
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Gergs A, Preuss TG, Palmqvist A. Double trouble at high density: cross-level test of resource-related adaptive plasticity and crowding-related fitness. PLoS One 2014; 9:e91503. [PMID: 24626228 PMCID: PMC3953409 DOI: 10.1371/journal.pone.0091503] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 02/12/2014] [Indexed: 11/19/2022] Open
Abstract
Population size is often regulated by negative feedback between population density and individual fitness. At high population densities, animals run into double trouble: they might concurrently suffer from overexploitation of resources and also from negative interference among individuals regardless of resource availability, referred to as crowding. Animals are able to adapt to resource shortages by exhibiting a repertoire of life history and physiological plasticities. In addition to resource-related plasticity, crowding might lead to reduced fitness, with consequences for individual life history. We explored how different mechanisms behind resource-related plasticity and crowding-related fitness act independently or together, using the water flea Daphnia magna as a case study. For testing hypotheses related to mechanisms of plasticity and crowding stress across different biological levels, we used an individual-based population model that is based on dynamic energy budget theory. Each of the hypotheses, represented by a sub-model, is based on specific assumptions on how the uptake and allocation of energy are altered under conditions of resource shortage or crowding. For cross-level testing of different hypotheses, we explored how well the sub-models fit individual level data and also how well they predict population dynamics under different conditions of resource availability. Only operating resource-related and crowding-related hypotheses together enabled accurate model predictions of D. magna population dynamics and size structure. Whereas this study showed that various mechanisms might play a role in the negative feedback between population density and individual life history, it also indicated that different density levels might instigate the onset of the different mechanisms. This study provides an example of how the integration of dynamic energy budget theory and individual-based modelling can facilitate the exploration of mechanisms behind the regulation of population size. Such understanding is important for assessment, management and the conservation of populations and thereby biodiversity in ecosystems.
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Affiliation(s)
- André Gergs
- Department of Environmental, Social and Spatial Change, Roskilde University, Roskilde, Denmark
| | - Thomas G. Preuss
- Institute for Environmental Research, RWTH Aachen University, Aachen, Germany
| | - Annemette Palmqvist
- Department of Environmental, Social and Spatial Change, Roskilde University, Roskilde, Denmark
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