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Rasmussen SB, Bosker T, Barmentlo SH, Berglund O, Vijver MG. Non-conventional endpoints show higher sulfoxaflor toxicity to Chironomus riparius than conventional endpoints in a multistress environment. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 275:107074. [PMID: 39241466 DOI: 10.1016/j.aquatox.2024.107074] [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: 07/24/2024] [Revised: 08/27/2024] [Accepted: 08/31/2024] [Indexed: 09/09/2024]
Abstract
Evidence grows that standard toxicity testing might underestimate the environmental risk of neurotoxic insecticides. Behavioural endpoints such as locomotion and mobility have been suggested as sensitive and ecologically relevant additions to the standard tested endpoints. Possible interactive effects of chemicals and additional stressors are typically overlooked in standardised testing. Therefore, we aimed to investigate how concurrent exposure to environmental stressors (increased temperature and predation cues) and a nicotinic acetylcholine receptor (nAChR)-modulating insecticide ('sulfoxaflor') impact Chironomus riparius across a range of conventional and non-conventional endpoints. We used a multifactorial experimental design encompassing three stressors, sulfoxaflor (2.0-110 µg/L), predation risk (presence/absence of predatory cues), and elevated temperature (20 °C and 23 °C), yielding a total of 24 distinct treatment conditions. Additional stressors did not change the sensitivity of C. riparius to sulfoxaflor. To assess potential additive effects, we applied an Independent Action (IA) model to predict the impact on eight endpoints, including conventional endpoints (growth, survival, total emergence, and emergence time) and less conventional endpoints (the size of the adults, swimming abilities and exploration behaviour). For the conventional endpoints, observed effects were either lower than expected or well-predicted by the IA model. In contrast, we found greater than predicted effects of predation cues and temperature in combination with sulfoxaflor on adult size, larval exploration, and swimming behaviour. However, in contrast to the non-conventional endpoints, no conventional endpoints detected interactive effects of the neurotoxic insecticide and the environmental stressors. Acknowledging these interactions, increasing ecological context of ecotoxicological test systems may, therefore, advance environmental risk analysis and interpretation as the safe environmental concentrations of neurotoxic insecticides depend on the context of both the test organism and its environment.
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Affiliation(s)
- Sofie B Rasmussen
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300 RA Leiden, the Netherlands
| | - Thijs Bosker
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300 RA Leiden, the Netherlands
| | - S Henrik Barmentlo
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300 RA Leiden, the Netherlands
| | - Olof Berglund
- Department of Biology, Lund University, Lund, Sweden
| | - Martina G Vijver
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300 RA Leiden, the Netherlands.
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2
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Rasmussen SB, Bosker T, Ramanand GG, Vijver MG. Participatory hackathon to determine ecological relevant endpoints for a neurotoxin to aquatic and benthic invertebrates. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:22885-22899. [PMID: 38418784 PMCID: PMC10997722 DOI: 10.1007/s11356-024-32566-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/16/2024] [Indexed: 03/02/2024]
Abstract
The aim of this study is twofold: i) to determine innovative yet sensitive endpoints for sulfoxaflor and ii) to develop best practices for innovative teaching in ecotoxicology. To this end, a group of 52 MSc students participated in an environmental hackathon, during which they did creative toxicity testing on 5 freshwater invertebrate species: Daphnia magna, Chironomus riparius, Asellus aquaticus, Lymnaea stagnalis, and Anisus vortex. Involving the students in an active learning environment stimulated increased creativity and productivity. In total, 28 endpoints were investigated, including standard endpoints (e.g., mortality) as well as biomechanistic and energy-related endpoints. Despite high variances in the results, likely linked to the limited lab experience of the students and interpersonal differences, a promising set of endpoints was selected for further investigation. A more targeted follow-up experiment focused on the most promising organism and set of endpoints: biomechanistic endpoints of C. riparius larvae. Larvae were exposed to a range of sulfoxaflor concentrations (0.90-67.2 μg/L) for 21 days. Video tracking showed that undulation and swimming were significantly reduced at 11.1 μg sulfoxaflor/L after 9 days of exposure, and an EC50 = 10.6 μg/L for mean velocities of the larvae in the water phase was found. Biomechanistic endpoints proved much more sensitive than mortality, for which an LC50 value of 116 μg/L was found on Day 9. Our results show that performing a hackathon with students has excellent potential to find sensitive endpoints that can subsequently be verified using more targeted and professional follow-up experiments. Furthermore, utilising hackathon events in teaching can increase students' enthusiasm about ecotoxicology, driving better learning experiences.
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Affiliation(s)
- Sofie B Rasmussen
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300, RA, Leiden, The Netherlands.
| | - Thijs Bosker
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300, RA, Leiden, The Netherlands
- Leiden University College, Leiden University, P.O. Box 13228, 2501, EE, The Hague, The Netherlands
| | - Giovani G Ramanand
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300, RA, Leiden, The Netherlands
| | - Martina G Vijver
- Institute of Environmental Sciences, Leiden University, P.O. Box 9518, 2300, RA, Leiden, The Netherlands
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3
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Redondo-López S, León AC, Jiménez K, Solano K, Blanco-Peña K, Mena F. Transient exposure to sublethal concentrations of a pesticide mixture (chlorpyrifos-difenoconazole) caused different responses in fish species from different trophic levels of the same community. Comp Biochem Physiol C Toxicol Pharmacol 2022; 251:109208. [PMID: 34626844 DOI: 10.1016/j.cbpc.2021.109208] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/08/2021] [Accepted: 09/29/2021] [Indexed: 01/16/2023]
Abstract
The assessment of early effects caused in biota by sublethal exposure to pesticide mixtures should enhance the realism in the ecological risk assessment for agricultural landscapes. This study aimed to evaluate sub-individual responses in fish, which can be linked with outcomes at higher levels of biological organization and affect their trophic relationships. A multilevel biomarker approach was applied to assess the effects of a 48 h exposure of two freshwater mesoamerican fish species (Parachromis dovii and Poecilia gillii) to a mixture of sublethal concentrations of chlorpyrifos (5 μg/L) and difenoconazole (325 μg/L). Transcriptomic induction of cyp1A and the activities of 7-ethoxy-resorufin-O-distillase (EROD) and glutathione S-transferase (GST) were measured as biotransformation-related biomarkers; cholinesterase activity (ChE) was assessed as a neurotoxicity biomarker; resting metabolic rate (RMR) was measured as a physiological biomarker; and the movement of fish in a dark-light environment as a behavior biomarker. The exposure to the mixture had evident effects on P. gillii, with significant induction of cyp1A transcription, increased EROD activity, ChE inhibition in muscle, and increased permanence in the light side of the dark-light environment. Meanwhile, P. dovii only showed significant induction of cyp1A, without evidence of neurotoxicity or changes in behavior. This study demonstrates that the severity of the effects caused by the exposure to a mixture of pesticides can differ among species from the same trophic chain. The potential impairment of predator-prey relationships is a relevant effect that pesticide pollution can cause and it should be considered for the risk assessment of such contaminants.
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Affiliation(s)
- Sergei Redondo-López
- Instituto Regional de Estudios en Sustancias Tóxicas, Central American Institute for Studies on Toxic Substances (IRET), Costa Rica.
| | - Ana C León
- Escuela de Medicina Veterinaria, School of Veterinary Medicine, Universidad Nacional, Costa Rica.
| | - Katherine Jiménez
- Instituto Regional de Estudios en Sustancias Tóxicas, Central American Institute for Studies on Toxic Substances (IRET), Costa Rica
| | - Karla Solano
- Instituto Regional de Estudios en Sustancias Tóxicas, Central American Institute for Studies on Toxic Substances (IRET), Costa Rica
| | - Kinndle Blanco-Peña
- Instituto Regional de Estudios en Sustancias Tóxicas, Central American Institute for Studies on Toxic Substances (IRET), Costa Rica
| | - Freylan Mena
- Instituto Regional de Estudios en Sustancias Tóxicas, Central American Institute for Studies on Toxic Substances (IRET), Costa Rica.
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Bownik A, Wlodkowic D. Applications of advanced neuro-behavioral analysis strategies in aquatic ecotoxicology. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 772:145577. [PMID: 33770877 DOI: 10.1016/j.scitotenv.2021.145577] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Despite mounting evidence of pleiotropic ecological risks, the understanding of the eco-neurotoxic impact of most industrially relevant chemicals is still very limited. In particularly the acute and chronic exposures to industrial pollutants on nervous systems and thus potential alterations in ecological fitness remain profoundly understudied. Since the behavioral phenotype is the highest-level and functional manifestation of integrated neurological functions, the alterations in neuro-behavioral traits have been postulated as very sensitive and physiologically integrative endpoints to assess eco-neurotoxicological risks associated with industrial pollutants. Due to a considerable backlog of risk assessments of existing and new production chemicals there is a need for a paradigm shift from high cost, low throughput ecotoxicity test models to next generation systems amenable to higher throughput. In this review we concentrate on emerging aspects of laboratory-based neuro-behavioral phenotyping approaches that can be amenable for rapid prioritizing pipelines. We outline the importance of development and applications of innovative neuro-behavioral assays utilizing small aquatic biological indicators and demonstrate emerging concepts of high-throughput chemo-behavioral phenotyping. We also discuss new analytical approaches to effectively and rapidly evaluate the impact of pollutants on higher behavioral functions such as sensory-motor assays, decision-making and cognitive behaviors using innovative model organisms. Finally, we provide a snapshot of most recent analytical approaches that can be applied to elucidate mechanistic rationale that underlie the observed neuro-behavioral alterations upon exposure to pollutants. This review is intended to outline the emerging opportunities for innovative multidisciplinary research and highlight the existing challenges as well barriers to future development.
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Affiliation(s)
- Adam Bownik
- Department of Hydrobiology and Protection of Ecosystems, Faculty of Environmental Biology, University of Life Sciences, Lublin, Poland
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Rebechi D, Palacio-Cortés AM, Richardi VS, Beltrão T, Vicentini M, Grassi MT, da Silva SB, Alessandre T, Hasenbein S, Connon R, Navarro-Silva MA. Molecular and biochemical evaluation of effects of malathion, phenanthrene and cadmium on Chironomus sancticaroli (Diptera: Chironomidae) larvae. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 211:111953. [PMID: 33482495 DOI: 10.1016/j.ecoenv.2021.111953] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/27/2020] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
In-vitro effects of sub-lethal concentrations of malathion, phenanthrene (Phe) and cadmium (Cd) were tested on Chironomus sancticaroli larvae in acute bioassays by measuring biochemical and molecular parameters. Malathion was evaluated at 0.001, 0.0564 and 0.1006 mg L-1; Phe at 0.0025, 1.25 and 2.44 mg L-1; and Cd at 0.001, 3.2 and 7.4 mg L-1. The recovery test carried out at the highest concentration of each compound showed that survival of larvae exposed to Phe ranged from 4% to 5%, while the effects of malathion and Cd were irreversible, not allowing the emergence of adults. Results showed that malathion and Cd inhibited AChE, EST-α and ES-β activities at the two highest concentrations. Phe at 0.0025, 1.25 and 2.44 mg L-1; and Cd at 3.2 and 7.4 mg L-1 inhibited glutathione S-transferase activity. Oxidative stress was exclusively induced by the lowest concentration of malathion considering SOD activity once CAT was unaffected by the stressors. Lipid peroxidation was registered exclusively by malathion at the two highest concentrations, and total hemoglobin content was only reduced by Cd at the two highest concentrations. The relationship among biochemical results, examined using the PCA, evidenced that malathion and Cd concentrations were clustered into two groups, while Phe only formed one group. Four hemoglobin genes of C. sancticaroli were tested for the first time in this species, with Hemoglobin-C being upregulated by malathion. The toxicity ranking was malathion > Phe > Cd, while biochemical and molecular results showed the order malathion > Cd > Phe. Our results highlight the importance of combining different markers to understand the effects of the diverse compounds in aquatic organisms.
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Affiliation(s)
- Débora Rebechi
- Department of Zoology, Federal University of Paraná, Curitiba, Paraná, Brazil
| | | | | | - Tiago Beltrão
- Department of Zoology, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Maiara Vicentini
- Department of Zoology, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Marco Tadeu Grassi
- Department of Chemistry, Federal University of Paraná, Curitiba, Paraná, Brazil
| | | | - Thiago Alessandre
- Department of Chemistry, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Simone Hasenbein
- Department of Anatomy, Physiology & Cell Biology, University of California, Davis, CA, USA
| | - Richard Connon
- Department of Anatomy, Physiology & Cell Biology, University of California, Davis, CA, USA
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Kienle C, Vermeirssen ELM, Schifferli A, Singer H, Stamm C, Werner I. Effects of treated wastewater on the ecotoxicity of small streams - Unravelling the contribution of chemicals causing effects. PLoS One 2019; 14:e0226278. [PMID: 31881027 PMCID: PMC6934383 DOI: 10.1371/journal.pone.0226278] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 11/22/2019] [Indexed: 11/30/2022] Open
Abstract
Wastewater treatment plant effluents are important point sources of micropollutants. To assess how the discharge of treated wastewater affects the ecotoxicity of small to medium-sized streams we collected water samples up- and downstream of 24 wastewater treatment plants across the Swiss Plateau and the Jura regions of Switzerland. We investigated estrogenicity, inhibition of algal photosynthetic activity (photosystem II, PSII) and growth, and acetylcholinesterase (AChE) inhibition. At four sites, we measured feeding activity of amphipods (Gammarus fossarum) in situ as well as water flea (Ceriodaphnia dubia) reproduction in water samples. Ecotoxicological endpoints were compared with results from analyses of general water quality parameters as well as a target screening of a wide range of organic micropollutants with a focus on pesticides and pharmaceuticals using liquid chromatography high-resolution tandem mass spectrometry. Measured ecotoxicological effects in stream water varied substantially among sites: 17β-estradiol equivalent concentrations (EEQbio, indicating the degree of estrogenicity) were relatively low and ranged from 0.04 to 0.85 ng/L, never exceeding a proposed effect-based trigger (EBT) value of 0.88 ng/L. Diuron equivalent (DEQbio) concentrations (indicating the degree of photosystem II inhibition in algae) ranged from 2.4 to 1576 ng/L and exceeded the EBT value (70 ng/L) in one third of the rivers studied, sometimes even upstream of the WWTP. Parathion equivalent (PtEQbio) concentrations (indicating the degree of AChE inhibition) reached relatively high values (37 to 1278 ng/L) mostly exceeding the corresponding EBT (196 ng/L PtEQbio). Decreased feeding activity by amphipods or decreased water flea reproduction downstream compared to the upstream site was observed at one of four investigated sites only. Results of the combined algae assay (PSII inhibition) correlated best with results of chemical analysis for PSII inhibiting herbicides. Estrogenicity was partly and AChE inhibition strongly underestimated based on measured steroidal estrogens respectively organophosphate and carbamate insecticides. An impact of dissolved organic carbon on results of the AChE inhibition assay was obvious. For this assay more work is required to further explore the missing correlation of bioassay data with chemical analytical data. Overall, the discharge of WWTP effluent led to increased estrogenicity, PSII and AChE inhibition downstream, irrespective of upstream land use.
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Affiliation(s)
- Cornelia Kienle
- Swiss Centre for Applied Ecotoxicology, Dübendorf, Zürich, Switzerland
- * E-mail:
| | | | - Andrea Schifferli
- Swiss Centre for Applied Ecotoxicology, Dübendorf, Zürich, Switzerland
| | - Heinz Singer
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Zürich, Switzerland
| | - Christian Stamm
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Zürich, Switzerland
| | - Inge Werner
- Swiss Centre for Applied Ecotoxicology, Dübendorf, Zürich, Switzerland
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7
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Monteiro HR, Pestana JLT, Novais SC, Leston S, Ramos F, Soares AMVM, Devreese B, Lemos MFL. Assessment of fipronil toxicity to the freshwater midge Chironomus riparius: Molecular, biochemical, and organismal responses. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 216:105292. [PMID: 31546069 DOI: 10.1016/j.aquatox.2019.105292] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 08/01/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
Fipronil is a phenylpyrazole insecticide that entered the market to replace organochlorides and organophosphates. Fipronil impairs the regular inhibition of nerve impulses that ultimately result in paralysis and death of insects. Because of its use as a pest control, and due to runoff events, fipronil has been detected in freshwater systems near agricultural areas, and therefore might represent a threat to non-target aquatic organisms. In this study, the toxicity of fipronil to the freshwater midge Chironomus riparius was investigated at biochemical, molecular, and whole organism (e.g. growth, emergence, and behavior) levels. At the individual level, chronic (28 days) exposure to fipronil resulted in reduced larval growth and emergence with a lowest observed effect concentration (LOEC) of 0.081 μg L-1. Adult weight, which is directly linked to the flying performance and fecundity of midges, was also affected (LOEC = 0.040 μg L-1). Additionally, behavioral changes such as irregular burrowing behavior of C. riparius larvae (EC50 = 0.084 μg L-1) and impairment of adult flying performance were observed. At a biochemical level, acute (48 h) exposure to fipronil increased cellular oxygen consumption (as indicated by the increase of electron transport system (ETS) activity) and decreased antioxidant and detoxification defenses (as suggested by the decrease in catalase (CAT) and glutathione S-transferase (GST) activities). Exposure to fipronil also caused alterations in the fatty acid profile of C. riparius, since high levels of stearidonic acid (SDA) were observed. A comparison between exposed and non-exposed larvae also revealed alterations in the expression of globins, cytoskeleton and motor proteins, and proteins involved in protein biosynthesis. These alterations may aid in the interpretation of potential mechanisms of action that lead to the effects observed at the organism level. Present results show that environmentally relevant concentrations of fipronil are toxic to chironomid populations which call for monitoring of phenylpyrazole insecticides and of their ecological effects in freshwaters. Present results also emphasize the importance of complementing ecotoxicological data with molecular approaches such as proteomics, for a better interpretation of the mode of action of insecticides in aquatic invertebrates.
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Affiliation(s)
- Hugo R Monteiro
- Department of Biology and CESAM, University of Aveiro, Aveiro, Portugal; MARE - Marine and Environmental Sciences Centre, ESTM, Polytechnic Institute of Leiria, Peniche, Portugal; Department of Biochemistry and Microbiology, Laboratory for Microbiology, Ghent University, Ghent, Belgium.
| | - João L T Pestana
- Department of Biology and CESAM, University of Aveiro, Aveiro, Portugal
| | - Sara C Novais
- MARE - Marine and Environmental Sciences Centre, ESTM, Polytechnic Institute of Leiria, Peniche, Portugal
| | - Sara Leston
- CFE - Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal; REQUIMTE/LAQV, Pharmacy Faculty, University of Coimbra, Coimbra, Portugal
| | - Fernando Ramos
- REQUIMTE/LAQV, Pharmacy Faculty, University of Coimbra, Coimbra, Portugal
| | | | - Bart Devreese
- Department of Biochemistry and Microbiology, Laboratory for Microbiology, Ghent University, Ghent, Belgium
| | - Marco F L Lemos
- MARE - Marine and Environmental Sciences Centre, ESTM, Polytechnic Institute of Leiria, Peniche, Portugal
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Heuschele J, Lode T, Andersen T, Borgå K, Titelman J. An affordable and automated imaging approach to acquire highly resolved individual data-an example of copepod growth in response to multiple stressors. PeerJ 2019; 7:e6776. [PMID: 31041153 PMCID: PMC6476288 DOI: 10.7717/peerj.6776] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/12/2019] [Indexed: 01/21/2023] Open
Abstract
Individual trait variation is essential for populations to cope with multiple stressors and continuously changing environments. The immense number of possible stressor combinations and the influence of phenotypic variation makes experimental testing for effects on organisms challenging. The acquisition of such data requires many replicates and is notoriously laborious. It is further complicated when responses occur over short time periods. To overcome such challenges, we developed an automated imaging platform to acquire temporally highly resolved individual data. We tested this platform by exposing copepods to a combination of a biotic stressor (predator cues) and a toxicant (copper) and measured the growth response of individual copepods. We tested the automatically acquired data against published manually acquired data with much lower temporal resolution. We find the same general potentiating effects of predator cues on the adverse effects of copper, and the influence of an individual’s clutch identity on its ability to resist stress, between the data obtained from low and high temporal resolution. However, when using the high temporal resolution, we also uncovered effects of clutch ID on the timing and duration of stage transitions, which highlights the importance of considering phenotypic variation in ecotoxicological testing. Phenotypic variation is usually not acknowledged in ecotoxicological testing. Our approach is scalable, affordable, and adjustable to accommodate both aquatic and terrestrial organisms, and a wide range of visually detectable endpoints. We discuss future extensions that would further widen its applicability.
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Affiliation(s)
- Jan Heuschele
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Torben Lode
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Tom Andersen
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Katrine Borgå
- Department of Biosciences, University of Oslo, Oslo, Norway
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Hayman NT, Hentschel BT, Renick VC, Anderson TW. Combined effects of flow speed and sub-lethal insecticide exposure on predator-prey interactions between the California killifish and an infaunal polychaete. ECOTOXICOLOGY (LONDON, ENGLAND) 2019; 28:117-131. [PMID: 30547329 DOI: 10.1007/s10646-018-2005-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Hydrodynamics and pollution affect estuarine populations, but their ecological effects have rarely been studied in combination. We conducted two laboratory experiments to quantify whether predator-prey interactions between California killifish, Fundulus parvipinnis, and the polychaete Polydora cornuta vary with flow speed and chlorpyrifos exposure. In one experiment, only F. parvipinnis was exposed to chlorpyrifos; in the other, only P. cornuta was exposed. The flume included a 300-cm2 area of sediment with 24 P. cornuta in a central patch (98 cm2). We videotaped groups of three killifish for 50 min at one of four flow speeds (6, 9, 12, or 15 cm/s) and recorded the proportion of bites directed at the prey patch. Unexposed killifish directed 70% of their bites at the prey patch at 6 cm/s, and prey-patch selection decreased as flow increased. Killifish exposed to chlorpyrifos directed 41% of their bites at the prey patch at 6 cm/s with reduced prey-patch selection relative to unexposed fish at 9 and 12 cm/s. At 15 cm/s, both exposed and unexposed fish displayed non-selective biting. Worms were videotaped to quantify their deposit- and suspension-feeding activities. Exposing worms to chlorpyrifos reduced total feeding activity by ~30%. Suspension feeding was more common at faster flow speeds, but the time worms spent suspension feeding relative to deposit feeding was unaffected by chlorpyrifos. No behavioral changes were noted in either species when the other was exposed to chlorpyrifos. This study highlights how hydrodynamic conditions can alter the relative importance of a toxicant's effects on predator-prey interactions.
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Affiliation(s)
- Nicholas T Hayman
- Department of Biology and Coastal and Marine Institute, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-4614, USA.
| | - Brian T Hentschel
- Department of Biology and Coastal and Marine Institute, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-4614, USA
| | - Violet C Renick
- Department of Biology and Coastal and Marine Institute, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-4614, USA
| | - Todd W Anderson
- Department of Biology and Coastal and Marine Institute, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-4614, USA
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Legradi JB, Di Paolo C, Kraak MHS, van der Geest HG, Schymanski EL, Williams AJ, Dingemans MML, Massei R, Brack W, Cousin X, Begout ML, van der Oost R, Carion A, Suarez-Ulloa V, Silvestre F, Escher BI, Engwall M, Nilén G, Keiter SH, Pollet D, Waldmann P, Kienle C, Werner I, Haigis AC, Knapen D, Vergauwen L, Spehr M, Schulz W, Busch W, Leuthold D, Scholz S, vom Berg CM, Basu N, Murphy CA, Lampert A, Kuckelkorn J, Grummt T, Hollert H. An ecotoxicological view on neurotoxicity assessment. ENVIRONMENTAL SCIENCES EUROPE 2018; 30:46. [PMID: 30595996 PMCID: PMC6292971 DOI: 10.1186/s12302-018-0173-x] [Citation(s) in RCA: 139] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 10/31/2018] [Indexed: 05/04/2023]
Abstract
The numbers of potential neurotoxicants in the environment are raising and pose a great risk for humans and the environment. Currently neurotoxicity assessment is mostly performed to predict and prevent harm to human populations. Despite all the efforts invested in the last years in developing novel in vitro or in silico test systems, in vivo tests with rodents are still the only accepted test for neurotoxicity risk assessment in Europe. Despite an increasing number of reports of species showing altered behaviour, neurotoxicity assessment for species in the environment is not required and therefore mostly not performed. Considering the increasing numbers of environmental contaminants with potential neurotoxic potential, eco-neurotoxicity should be also considered in risk assessment. In order to do so novel test systems are needed that can cope with species differences within ecosystems. In the field, online-biomonitoring systems using behavioural information could be used to detect neurotoxic effects and effect-directed analyses could be applied to identify the neurotoxicants causing the effect. Additionally, toxic pressure calculations in combination with mixture modelling could use environmental chemical monitoring data to predict adverse effects and prioritize pollutants for laboratory testing. Cheminformatics based on computational toxicological data from in vitro and in vivo studies could help to identify potential neurotoxicants. An array of in vitro assays covering different modes of action could be applied to screen compounds for neurotoxicity. The selection of in vitro assays could be guided by AOPs relevant for eco-neurotoxicity. In order to be able to perform risk assessment for eco-neurotoxicity, methods need to focus on the most sensitive species in an ecosystem. A test battery using species from different trophic levels might be the best approach. To implement eco-neurotoxicity assessment into European risk assessment, cheminformatics and in vitro screening tests could be used as first approach to identify eco-neurotoxic pollutants. In a second step, a small species test battery could be applied to assess the risks of ecosystems.
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Affiliation(s)
- J. B. Legradi
- Institute for Environmental Research, Department of Ecosystem Analysis, ABBt–Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- Environment and Health, VU University, 1081 HV Amsterdam, The Netherlands
| | - C. Di Paolo
- Institute for Environmental Research, Department of Ecosystem Analysis, ABBt–Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - M. H. S. Kraak
- FAME-Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
| | - H. G. van der Geest
- FAME-Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
| | - E. L. Schymanski
- Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, 6 Avenue du Swing, 4367 Belvaux, Luxembourg
| | - A. J. Williams
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Dr., Research Triangle Park, NC 27711 USA
| | - M. M. L. Dingemans
- KWR Watercycle Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, The Netherlands
| | - R. Massei
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, Leipzig, Germany
| | - W. Brack
- Department Effect-Directed Analysis, Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, Leipzig, Germany
| | - X. Cousin
- Ifremer, UMR MARBEC, Laboratoire Adaptation et Adaptabilités des Animaux et des Systèmes, Route de Maguelone, 34250 Palavas-les-Flots, France
- INRA, UMR GABI, INRA, AgroParisTech, Domaine de Vilvert, Batiment 231, 78350 Jouy-en-Josas, France
| | - M.-L. Begout
- Ifremer, Laboratoire Ressources Halieutiques, Place Gaby Coll, 17137 L’Houmeau, France
| | - R. van der Oost
- Department of Technology, Research and Engineering, Waternet Institute for the Urban Water Cycle, Amsterdam, The Netherlands
| | - A. Carion
- Laboratory of Evolutionary and Adaptive Physiology, Institute of Life, Earth and Environment, University of Namur, 5000 Namur, Belgium
| | - V. Suarez-Ulloa
- Laboratory of Evolutionary and Adaptive Physiology, Institute of Life, Earth and Environment, University of Namur, 5000 Namur, Belgium
| | - F. Silvestre
- Laboratory of Evolutionary and Adaptive Physiology, Institute of Life, Earth and Environment, University of Namur, 5000 Namur, Belgium
| | - B. I. Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstr. 15, 04318 Leipzig, Germany
- Eberhard Karls University Tübingen, Environmental Toxicology, Center for Applied Geosciences, 72074 Tübingen, Germany
| | - M. Engwall
- MTM Research Centre, School of Science and Technology, Örebro University, Fakultetsgatan 1, 70182 Örebro, Sweden
| | - G. Nilén
- MTM Research Centre, School of Science and Technology, Örebro University, Fakultetsgatan 1, 70182 Örebro, Sweden
| | - S. H. Keiter
- MTM Research Centre, School of Science and Technology, Örebro University, Fakultetsgatan 1, 70182 Örebro, Sweden
| | - D. Pollet
- Faculty of Chemical Engineering and Biotechnology, University of Applied Sciences Darmstadt, Stephanstrasse 7, 64295 Darmstadt, Germany
| | - P. Waldmann
- Faculty of Chemical Engineering and Biotechnology, University of Applied Sciences Darmstadt, Stephanstrasse 7, 64295 Darmstadt, Germany
| | - C. Kienle
- Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Überlandstrasse 133, 8600 Dübendorf, Switzerland
| | - I. Werner
- Swiss Centre for Applied Ecotoxicology Eawag-EPFL, Überlandstrasse 133, 8600 Dübendorf, Switzerland
| | - A.-C. Haigis
- Institute for Environmental Research, Department of Ecosystem Analysis, ABBt–Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - D. Knapen
- Zebrafishlab, Veterinary Physiology and Biochemistry, University of Antwerp, Wilrijk, Belgium
| | - L. Vergauwen
- Zebrafishlab, Veterinary Physiology and Biochemistry, University of Antwerp, Wilrijk, Belgium
| | - M. Spehr
- Institute for Biology II, Department of Chemosensation, RWTH Aachen University, Aachen, Germany
| | - W. Schulz
- Zweckverband Landeswasserversorgung, Langenau, Germany
| | - W. Busch
- Department of Bioanalytical Ecotoxicology, UFZ–Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - D. Leuthold
- Department of Bioanalytical Ecotoxicology, UFZ–Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - S. Scholz
- Department of Bioanalytical Ecotoxicology, UFZ–Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - C. M. vom Berg
- Department of Environmental Toxicology, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Dübendorf, 8600 Switzerland
| | - N. Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Canada
| | - C. A. Murphy
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, USA
| | - A. Lampert
- Institute of Physiology (Neurophysiology), Aachen, Germany
| | - J. Kuckelkorn
- Section Toxicology of Drinking Water and Swimming Pool Water, Federal Environment Agency (UBA), Heinrich-Heine-Str. 12, 08645 Bad Elster, Germany
| | - T. Grummt
- Section Toxicology of Drinking Water and Swimming Pool Water, Federal Environment Agency (UBA), Heinrich-Heine-Str. 12, 08645 Bad Elster, Germany
| | - H. Hollert
- Institute for Environmental Research, Department of Ecosystem Analysis, ABBt–Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
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11
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Alonso Á, García-Periñán E, Camargo JA. Development of a Low-Cost Ecotoxicological Bioassay Based on the Feeding Behaviour of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 71:553-560. [PMID: 27677615 DOI: 10.1007/s00244-016-0316-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/10/2016] [Indexed: 06/06/2023]
Abstract
Conventional acute tests are not suited to assess the effects of toxicants, because they do not use the concentrations that are usually found in natural ecosystems. By contrast, nonlethal realistic concentrations may cause deleterious effects on animal fitness as a consequence of behaviour impairment. Behaviour is a good integrative variable of complex biochemical and physiological processes. Therefore, bioassays based on behaviour are a useful tool in ecotoxicology. In this study, two bioassays were conducted: (1) acute bioassay (48 h) of acetone on the aquatic snail Potamopyrgus antipodarum, and (2) video-recording behavioural bioassay with pulse exposures to acetone to assess its effects on feeding behaviour. In the latter, animals were exposed to three pulses of acetone (24 h each) with 6 days of postexposure after each pulse. This design allowed us to assess the degree of feeding behaviour recovery after exposure and the effects of repeated pulses. Our results show that postexposure periods have an important effect on the recovery of normal feeding behaviour and that this developed bioassay is an ecotoxicological tool with a relatively low-cost and a short-time consuming. The application of this new tool to different ecotoxicological requirements is discussed.
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Affiliation(s)
- Álvaro Alonso
- Unidad Docente de Ecología, Departamento de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain.
| | - Eder García-Periñán
- Unidad Docente de Ecología, Departamento de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain
| | - Julio A Camargo
- Unidad Docente de Ecología, Departamento de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805, Alcalá de Henares, Madrid, Spain
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12
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Groh KJ, Carvalho RN, Chipman JK, Denslow ND, Halder M, Murphy CA, Roelofs D, Rolaki A, Schirmer K, Watanabe KH. Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: II. A focus on growth impairment in fish. CHEMOSPHERE 2015; 120:778-792. [PMID: 25456049 DOI: 10.1016/j.chemosphere.2014.10.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 10/01/2014] [Accepted: 10/02/2014] [Indexed: 06/04/2023]
Abstract
Adverse outcome pathways (AOPs) organize knowledge on the progression of toxicity through levels of biological organization. By determining the linkages between toxicity events at different levels, AOPs lay the foundation for mechanism-based alternative testing approaches to hazard assessment. Here, we focus on growth impairment in fish to illustrate the initial stages in the process of AOP development for chronic toxicity outcomes. Growth is an apical endpoint commonly assessed in chronic toxicity tests for which a replacement is desirable. Based on several criteria, we identified reduction in food intake to be a suitable key event for initiation of middle-out AOP development. To start exploring the upstream and downstream links of this key event, we developed three AOP case studies, for pyrethroids, selective serotonin reuptake inhibitors (SSRIs) and cadmium. Our analysis showed that the effect of pyrethroids and SSRIs on food intake is strongly linked to growth impairment, while cadmium causes a reduction in growth due to increased metabolic demands rather than changes in food intake. Locomotion impairment by pyrethroids is strongly linked to their effects on food intake and growth, while for SSRIs their direct influence on appetite may play a more important role. We further discuss which alternative tests could be used to inform on the predictive key events identified in the case studies. In conclusion, our work demonstrates how the AOP concept can be used in practice to assess critically the knowledge available for specific chronic toxicity cases and to identify existing knowledge gaps and potential alternative tests.
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Affiliation(s)
- Ksenia J Groh
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Department of Chemistry and Applied Biosciences, 8093 Zürich, Switzerland.
| | - Raquel N Carvalho
- European Commission, Joint Research Centre, Institute for Environment and Sustainability, Water Resources Unit, 21027 Ispra, Italy
| | | | - Nancy D Denslow
- University of Florida, Department of Physiological Sciences, Center for Environmental and Human Toxicology and Genetics Institute, 32611 Gainesville, FL, USA
| | - Marlies Halder
- European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Systems Toxicology Unit, 21027 Ispra, Italy
| | - Cheryl A Murphy
- Michigan State University, Fisheries and Wildlife, Lyman Briggs College, 48824 East Lansing, MI, USA
| | - Dick Roelofs
- VU University, Institute of Ecological Science, 1081 HV Amsterdam, The Netherlands
| | - Alexandra Rolaki
- European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Systems Toxicology Unit, 21027 Ispra, Italy
| | - Kristin Schirmer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Department of Environmental Systems Science, 8092 Zürich, Switzerland; EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne, Switzerland
| | - Karen H Watanabe
- Oregon Health & Science University, Institute of Environmental Health, Division of Environmental and Biomolecular Systems, 97239-3098 Portland, OR, USA
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13
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Gutierrez MF, Negro CL. Predator-prey imbalances due to a pesticide: density and applicability timing as determining factors for experimental assessments. ECOTOXICOLOGY (LONDON, ENGLAND) 2014; 23:1210-1219. [PMID: 24903805 DOI: 10.1007/s10646-014-1264-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/21/2014] [Indexed: 06/03/2023]
Abstract
Predator-prey relationships are determining factors in sustaining community structure but xenobiotics, including pesticides, have the potential to alter them, causing imbalances at the ecosystem level. Although invertebrate predation on zooplankton is of high importance in shallow lakes, there is still little information regarding disturbances on this trophic interaction. This work assessed the potential effects of a chlorpyrifos-based pesticide (CLP) on the interaction between prawns Macrobrachium borellii and cladocerans Ceriodaphnia dubia, taking into account prey densities, specific time of exposure and contamination level. The analysis was focused on the specific sensitivity of both species and, especially, on the predation rate of M. borellii on C. dubia. The latter was evaluated through different treatments that combined predator and/or prey exposure to the insecticide, before (lapse of 12 h) or during the interaction. Under low prey density, when prawns were previously exposed to the insecticide, their consumption rate was lower than that of controls. Conversely, when cladocerans or both species were previously exposed, the prawns' feeding rate was higher. Under high prey density, there were no substantial differences among treatments. Comparatively, cladocerans were significantly more consumed when the exposure of both species was performed before rather than during the interaction. From the results obtained, it can be assumed that the trophic interaction under study is sensitive to CLP and that individual density and specific time of exposure are important variables to be considered in similar studies in order to obtain realistic results.
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14
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Köhler HR, Triebskorn R. Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 2013; 341:759-65. [PMID: 23950533 DOI: 10.1126/science.1237591] [Citation(s) in RCA: 429] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
During the past 50 years, the human population has more than doubled and global agricultural production has similarly risen. However, the productive arable area has increased by just 10%; thus the increased use of pesticides has been a consequence of the demands of human population growth, and its impact has reached global significance. Although we often know a pesticide's mode of action in the target species, we still largely do not understand the full impact of unintended side effects on wildlife, particularly at higher levels of biological organization: populations, communities, and ecosystems. In these times of regional and global species declines, we are challenged with the task of causally linking knowledge about the molecular actions of pesticides to their possible interference with biological processes, in order to develop reliable predictions about the consequences of pesticide use, and misuse, in a rapidly changing world.
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Affiliation(s)
- Heinz-R Köhler
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Tübingen, Germany.
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15
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Salice CJ, Kimberly DA. Environmentally relevant concentrations of a common insecticide increase predation risk in a freshwater gastropod. ECOTOXICOLOGY (LONDON, ENGLAND) 2013; 22:42-49. [PMID: 23053786 DOI: 10.1007/s10646-012-1001-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/17/2012] [Indexed: 06/01/2023]
Abstract
Ecological receptors are faced with a multitude of stressors that include abiotic and biotic factors creating a challenge for assessing risk of chemical exposure. Of particular interest and importance are the effects of contaminants on inter-species interactions such as competition and predator-prey relationships. The objective of this study was to determine whether environmentally relevant concentrations of the commonly used insecticide, malathion, would alter predator avoidance behavior in a freshwater gastropod that could translate to increased predation risk. We exposed adult Physa pomilia snails to 0, 0.25, or 1.0 mg/L malathion for 2, 24, or 48 h and evaluated predator avoidance using a behavioral assay in which snails were exposed to cues from predatory crayfish. We found a significant reduction in predator avoidance in snails exposed to both concentrations of malathion after 48 h of exposure. To evaluate whether observed effects of malathion on predator avoidance actually increased susceptibility of snails to predators, we conducted a predator challenge experiment. Snails exposed to 0.25 mg/L malathion for 48 h were significantly more susceptible to predation. That increased predation risk was evident 48 h after initial malathion exposures is a unique result because most studies have evaluated behavioral responses soon after (<12 h) initiation of pesticide exposure. The extent to which the observed interactions affect natural populations, and the mechanisms through which they are mediated are largely unexplored. However, our study is the first to show that a commonly used insecticide decreases predator avoidance and may actually increase predation susceptibility in gastropods at concentrations several orders of magnitude below acute toxicity levels.
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Affiliation(s)
- Christopher J Salice
- The Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, P.O. Box 41163, Lubbock, TX 79409, USA.
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16
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Gutierrez MF, Paggi JC, Gagneten AM. Infodisruptions in predator-prey interactions: xenobiotics alter microcrustaceans responses to fish infochemicals. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2012; 81:11-16. [PMID: 22551684 DOI: 10.1016/j.ecoenv.2012.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 03/22/2012] [Accepted: 04/02/2012] [Indexed: 05/31/2023]
Abstract
Chemical communication is one of the most important ecological phenomena promoting the maintenance of ecosystem dynamics. In predator-prey interactions, mediation signals allow prey to detect their predators and can be crucial in the process of avoiding them. Since organisms in many natural waterbodies are often subjected to anthropogenic stressors, it is hypothesised that low concentrations of xenobiotic compounds can disturb this chemical communication, acting as infodisruptors. This study analyzes whether two anthropogenic pollutants (chromium and an insecticide) interfere in two freshwater predator-prey interactions, by altering the behavioural responses of a cladoceran and a copepod species to a fish chemical cue. The concentrations tested were lower than those considered innocuous under international water quality guidelines, and two types of behaviour were analysed: escape ability and depth selection in an artificial water column. Both species tested demonstrated a higher escape ability when exposed to the cue than when they were not exposed. Xenobiotics modified the responses of the copepod in opposite ways: chromium inhibited this behaviour and the insecticide prompted a higher than expected level of escape ability. The depth selection patterns were different between N. conifer and C. dubia. Fish kairomones did not modify them, however chromium and the insecticide caused important alterations in both cases. Such disruptions would be detrimental to the organisms' life cycle trajectories, which, in natural systems, would cause longterm damage in trophic structure and in evolutionary processes.
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