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Dissertations / Theses on the topic 'Gammarus pulex'
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Fear, Lesley Anne. "Microbial ecology of the gut of Gammarus pulex." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250026.
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Crane, Mark. "The use of Gammarus pulex (L.) to assess pollution." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333512.
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Bollache, Loïc. "Sélection sexuelle, parasitisme et patterns d'appariement chez le crustacé amphipode Gammarus pulex." Lyon 1, 2001. http://www.theses.fr/2001LYO10206.
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La biologie de reproduction de Gammarus lupex est caractérisée par une phase de gardiennage précopulatoire couramment analysée comme une stratégie compétitive développée par les mâles afin d'assurer leur reproduction. Une homogamie en fonction de la taille est fréquemment observée lors de cette phase de gardiennage, tel que les grands mâles sont appariés aux grandes femelles, et les mâles d'une taille moindre aux femelles plus petites. Un suivi sur le terrain de plusieurs populations naturelles, complété par des expériences au laboratoire ont permis de préciser le ou les processus responsables de l'homogamie pour la taille chez Gammarus pulex. En confrontant les prédictions propres à chaque hypothèse avec le pattern observé dans les populations naturelles, les hypothèses de contraintes et de disponibilité des partenaires ont pu être réfutées. La sélection sexuelle apparaît désormais comme le processus majeur permettant d'expliquer l'homogamie. Nous avons comparé dans un second temps les effets de deux parasites acanthocéphales, Pomphorhyncus laevis et Polymorphus minutus sur le succès d'appariement des individus des deux sexes chez Gammarus pulex. Le succès d'appariement des mâles et des femelles parasitées s'avère être fortement affecté sur le terrain. Les mâles parasités sont moins compétitifs que les mâles sains, et les femelles infectées moins attractives que les femelles saines, principalement due à une diminution de leur fécondité. Le succès des mâles et des femelles parasités par P. Minutus est plus faible que celui des individus parasités par P. Laevis. Les différences observées entre les deux parasites doivent vraisemblablement être liées à leur impact au niveau de la physiologie de leur hôte intermédiaire, sans que l'on sache encore ce qui, à ce niveau, diffère réellement entre les deux espèces parasitaires.
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Clarke, Hazel Caroline. "Ecology and behaviour of the invasive freshwater amphipod gammarus pulex (L.)." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601109.
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The sucess of invasive species is said to depend upon the availability of resources, interactions with natural enemies and the abiotic environment. However, the behavioural interactions also play an important role. This thesis uses the freshwater amphipod Gammarus pulex (L.) to investigate the ecology and behaviour of an invasive species, with particular emphasis on female reproduction.
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Dick, Jaimie T. A. "Assessments and decisions during mate choice in Gammarus pulex (Crustacea: amphipoda)." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336112.
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Miller, Thomas Henry. "Measurement and modelling of pharmaceutical bioconcentration in an aquatic invertebrate, Gammarus pulex." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/measurement-and-modellingof-pharmaceutical-bioconcentration-in-an-aquatic-invertebrate-gammarus-pulex(0cb58627-4405-4096-b735-d5344357c171).html.
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The aim of this work was to understand the bioconcentration potential of pharmaceuticals in a freshwater invertebrate. The novelty of this work lies in several parts of which the most important was that a computational model was developed to successfully predict bioconcentration in invertebrates, which has not been achieved previously. For the first time, a developed analytical method using liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to determine the occurrence of pharmaceuticals in Gammarus pulex across several tributaries of the River Thames (London, UK). The occurrence reached low level ng g-1 concentrations and indicated that further experiments were needed to determine the accumulation potential. Toxicokinetic exposures were performed to characterise the bioconcentration potential of 16 pharmaceuticals. The determined bioconcentration factors (BCFs) remained below regulatory thresholds indicative of bioaccumulation, which contrasted field-derived bioaccumulation factors that would have triggered regulatory guidelines. However, the standardised models employed for kinetic BCF estimation were evaluated and it was found that model assumptions concerning the uptake rate constant were not reliable, leading to extremely important implications for regulatory bodies. In addition, the developed LC-MS/MS method determined phase I and phase II metabolites in G. pulex, indicating that these organisms are capable of extensive biotransformation of pharmaceuticals. To further understand uptake mechanisms such as passive diffusion, a modelling approach using artificial neural networks were developed to characterise the uptake of pharmaceuticals onto passive sampling devices. No previous investigations have aimed to predict uptake onto polar organic chemical integrative sampler devices and this work represented the first of its kind. The passive sampling models demonstrated good predictive accuracy at a fraction of the cost and time required by experimental measurements. Furthermore, the modelling gave mechanistic insight into molecular descriptors that were related to uptake onto passive samplers. The modelling approach was extended to predict bioconcentration of pharmaceuticals in fish and G. pulex using data from the literature and data determined from the toxicokinetic experiments presented here. Interestingly, the fish-based model could not be used to predict the invertebrate data. This indicated that either the class of compounds (pharmaceuticals) or the fish-to-invertebrate bioconcentration data could not be cross predicted. Thus, a standalone model was developed for the invertebrates and showed good predictive accuracy for this species. Overall, the work presented herein has achieved novel impact to address the lack of knowledge concerning bioconcentration in invertebrates.
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Holmgen, Jonas. "Ger olika temperaturförhållanden ¨trade off¨- effekter mellan tillväxt och exokutikulans tjocklek hos Gammarus pulex? En pilotstudie." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-928.
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<p>I rinnande vatten, så som bäckar och åar, har Gammarus pulex en viktig ställning i näringsväven. Arten bidrar till att bryta ner organiskt material och göra energin i detta tillgänglig för andra organismer. G. pulex är dessutom en viktig föda för ett stort antal predatorer. Flera studier visar att G. pulex reagerar på olika temperaturer. Tillväxthastighet, livslängd, reproduktion, aktivitet och syreförbrukning är exempel på karaktärer som påverkas av temperaturen. Ingen studie har tidigare behandlat om anläggningen av exokutikula påverkas av temperaturen. En höjd temperatur ökar tillväxthastigheten och detta skulle kunna ge minskade resurser till generering av exokutikula, såkallad ”trade off”. Min studie syftar till att undersöka hur G. pulex tvingas fördela sina resurser mellan tillväxt och exokutikulans tjocklek i förhållande till förändrade temperaturförhållande. Till undersökningen användes 80 djur från två naturliga system med en genomsnittlig temperaturskillnad på 1,9ºC. Säsongsvariation mellan höst och vinter studerades utifrån samma lokaler. Exokutikulans tjocklek mättes och kroppslängden användes som storleksreferens. Statistisk analys gjordes av kvoten exokutikulatjocklek/kroppslängd och ingen signifikant skillnad hittades mellan de olika grupperna. Denna studie visar att ingen ”trade off” finns mellan exokutikulans tjocklek och tillväxt hos G. pulex, varken i de två systemen, eller p.g.a. säsongsvariation, höst och vinter. Detta kan bero på Amfipoders möjligheter att återanvända kalcium för uppbyggnad av en ny exokutikula samt eventuell god tillgång på resurser. Dessutom ger en höjd metabolism vid ökad temperatur ökade möjligheter till en snabb generering av en ny exokutikula. Vidare studier bör göras i både naturliga och artificiella miljöer för att vidare undersöka en eventuell ”trade off” mellan tillväxt och exokutikula.</p>
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Bentley, Christopher R. "The pathophysiology of Pomphorhynchus laevis (Acanthocephala) in its intermediate host Gammarus pulex (Crustacea)." Thesis, Keele University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359161.
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Hadfield, Simon John. "Genetic structure and colonisation history of European and UK population of Gammarus pulex." Thesis, University of Hull, 2002. http://hydra.hull.ac.uk/resources/hull:5483.
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The structure of populations has been studied for many years and there have been three main factors that have been suggested as the cause for present-day distributions of species, those being environment, biology and history. With the use of molecular data and advanced phylogeographic approaches it is now possible to distinguish between the main causes of population structuring. The present study considers the extent of population structure in G. pulex on regional (UK) and large geographic (Europe) scales using studies of molecular genetic (allozymes, mtDNA sequencing and microsatellites) and morphological variation. Molecular analysis of Gammarus pulex in Europe revealed more diversity than previously thought. This was thought to be a consequence of two separate waves of colonisation after the formation of the major drainages in the Miocene. The UK appears to have been colonised once from either the Elbe, Mosel and Rhine drainages separately or cumulatively across the drainage basins late in the Pleistocene before a land bridge connection to mainland Europe was submerged. Limited molecular variation in the UK is thought to be a result of reduced genetic variation in the colonising individuals. This in turn was caused by repeated founder events during population expansion and contraction from European refugia. A detailed analysis of a transplantation experiment in 1950 in the Isle of Man revealed little genetic impoverishment of the introduced population when compared to the source. In contrast, morphological variation increased in the introduced population. Unlike in mainland Europe there was no historical explanation for the diversity recorded (as the introduced population was so young) and, in the absence of fragmentation, speciation and colonisation the contemporary forces of gene flow, selection and limited genetic drift are thought to be the determining factors in population structure.
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Amer, Aisha Arhouma Ali. "The effect of cadmium chloride on the biology of Gammarus pulex (Crustacea: Amphipoda)." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15496.
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Increased releases of cadmium to the aquatic environment have raised concern over the potential for adverse impacts on freshwater organisms in affected aquatic bodies. This thesis explored the responses of a common freshwater amphipod, Gammarus pulex (G. pulex) to sublethal concentrations of cadmium under different environmental conditions and at various stages of the lifestyle. Endpoints studied encompassed molecular, cellular, physiological and behavioural changes, to enable a comprehensive analysis of the effects of the organism. Exposure to sublethal concentrations of cadmium (Cd) (0.001, 0.005 and 0.01 mg Cd L–1) for 7 and 14 days, influenced the percent survival, induced lipid peroxidation and damaged DNA in haemolymph cells of G. pulex. These concentrations also reduced feeding and ventilation rates as well as the motility, in particular of the females, with increasing Cd concentration and time of exposure. Furthermore, Cd accumulation from water in the body tissues of the amphipods was lower than in their food, with increasing Cd concentrations. These results illustrate how concentrations of Cd below the Environmental Quality Standard for European waters can cause sublethal molecular and cellular damage after relatively short periods of exposure. Histopathological effects of Cd on the gills and hepatopancreas (mid-gut gland) were examined using light, scanning and transmission electron microscopy. Multiple effects were observed on the tissues and cell organelles including external alternations in the muscular fibres of the hepatopancreas, lysis of microvilli and morphological changes in mitochondria. Exposure to 0.01 mg Cd L–1 altered the epithelial layer of the gill, causing vacuolation and lysis across the whole gill structure. Mitochondria showed damage to the inner membrane, shortened cristae and swelling, with an increase in apoptosis at concentrations of 0.005 and 0.01 mg Cd L–1. Collectively, these results document the adverse effects of Cd on target organs at concentrations within the range found in freshwater bodies. An investigation of the effects of water hardness on bioaccumulation and toxicity showed that hardness of water inhibited Cd toxicity and protected the juveniles during long term exposures, without affecting growth rate and food consumption. Soft water reduced the rate of survival, growth rate and food consumption during chronic exposure to low Cd concentrations, and facilitated Cd accumulation in the body parts compared with juveniles exposed in hard water. The results show that water quality plays a vital role in reducing or increasing detrimental effects of low Cd concentrations on the early life stage of amphipods which are a source of food for many species in aquatic environments. Exposure to Cd led to an increase in metallothionein concentrations in the amphipods in both hard and soft water. It also caused disruption to ion/osmoregulation, which may represent one mechanism of compensation for the ions lost in the amphipods exposed to Cd in soft water. In conclusion, these results add to the body of evidence describing the sublethal toxicity of Cd, a priority pollutant, to a common freshwater sentinel species. These results are of relevance for future environmental management and remediation approaches, because they provide scientific data to help in assessing, interpreting and understanding the effects of the heavy metal Cd in freshwater environments.
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Gross, Melanie Yvette. "Effects of sewage effluent and nonylphenol on the fresh water amphipod Gammarus Pulex (L.)." Thesis, Royal Holloway, University of London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395482.
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Love, Adrian Charles. "The sub-lethal impacts of waste water effluent and its components on Gammarus pulex." Thesis, University of Portsmouth, 2017. https://researchportal.port.ac.uk/portal/en/theses/the-sublethal-impacts-of-waste-water-effluent-and-its-components-on-gammarus-pulex(fcb48eba-b5b1-48bd-87f4-5682713319eb).html.
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The prevalence of pharmaceuticals and personal care products (PPCPs) in lotic habitats is increasing, with the main source of these contaminants being effluent from waste water treatment works (WwTW). There is still much uncertainty about the impacts of these PPCPs at environmentally relevant concentrations and their potential effects on populations. This thesis provides an evaluation into the effects of WwTW, their effluent, and the PPCP they contain on a typical and important freshwater invertebrate, Gammarus pulex, using field and laboratory observations. A two-year investigation into G. pulex populations in sample points up-and downstream of two WwTW discharge points showed significant differences in the sizes of male and female G. pulex populations relative to the point of discharge, though the effects were not consistent between the two sites. There were more consistent changes on the frequency of intersex phenotypes and reproductive investment at and below the effluent discharge point suggesting the effluents are having a direct or indirect effect on the reproduction and development. The impact of effluent on behaviour was measured using automated and manual means. Animals’ activity and phototaxis, as well as feeding rate and pairing tendency was measured over three weeks’ exposure to two WwTW’s final effluents at 50% and 100% concentration. There was no significant difference between activity, phototaxis and feeding responses in effluent exposed animals and controls. Pairing was significantly more rapid in animals after exposure to both effluents which may be related to reproductive effects. A series of experiments were conducted to assess the effects of 5 PPCPs (diclofenac, fluoxetine, ibuprofen, propranolol, and triclosan), and a pharmaceutical mixture, on G. pulex. Effects were assessed in terms of activity, phototaxis, mortality, feeding rate and moulting frequency. Trials ranged from short term (1 week) exposures using toxic concentrations to chronic (3 week) exposures to environmentally relevant doses. There were significant sub-lethal effects at a range of concentrations, including hormetic responses. Significant mortalities were seen at triclosan concentrations at 0.01, 1 and 10μg L<sup>-1</sup>, and diclofenac and proporanolol concentrations of 10mg and 5mg L<sup>-1 </sup>respectively. Effects of drugs were associated with their mode of action or toxicity. Energy reserves were measured in terms of lipid and glycogen concentration. There was no significant effect on glycogen reserves, but lipid concentrations were significantly less after exposure to 0.1 μg L<sup>1</sup> diclofenac, 2 μg L<sup>-1</sup> ibuprofen and 0.5 μg L<sup>-1</sup> propranolol. Effect on reproduction was assessed through pairing frequency as well as embryo production. Significant negative effects were seen on pairing, after exposure to environmentally relevant concentrations of fluoxetine, diclofenac and triclosan, but this was not found to impact egg production with the exception of triclosan, where a reduction in the size and development of embryos was observed at concentrations of 0.1μg L<sup>-1</sup>. This study is the first long term investigation into G. pulex populations around WwTW. It shows the natural variability in population, sex distributions, and seasonal differences of this keystone aquatic invertebrate in two southern chalk streams receiving effluent discharges. It represents the first time the incidence and characteristics of intersex G. pulex have been studied and records a consistent increase in the frequency of this phenotype downstream of WwTWs which has not been identified before. Whether there are broader effects on intersex frequency on other invertebrates and the implications of this for the lotic ecology and water treatment processing is discussed. Of the PPCPs tested, triclosan and diclofenac showed the most consistent toxic effects across the end points assessed, ranging from subtle behavioural effects to lethality. This is of particular concern given the widespread use and incidence of the chemicals in sewage effluent and the toxic impacts seen here at environmentally relevant doses. Both chemicals are currently undergoing reviews by European and American regulatory bodies regarding their safety, potential impacts and acceptable environmental limits. The results of this study will be of use in informing this debate.
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Kingsley-Shadish, Antonipillai. "Behaviour of Gammarus pulex (L.) (Crustacea, Amphipoda) in response to intermittent pulses of dissolved copper." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248015.
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Dando, Chrtistine. "The effect of zinc on physiological function in Gammarus pulex : a between-individual variation approach." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274947.
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Adam, Olivier. "Impact des produits de traitement du bois sur les amphipodes Gammarus pulex (L. ) et Gammarus fossarum (K. ) : approches chimiques, hydro-écologique et écotoxicologique." Besançon, 2008. http://www.theses.fr/2008BESA2071.
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Afin de les protéger des attaques des champignons et des coléoptères, les bois d'oeuvre issus de résineux sont traités par des fongicides et/ou des insecticides lors d'une ou de plusieurs étapes de leur transformation. Ces derniers sont le plus fréquemment la cyperméthrine et la deltarnéthrine (insecticides de la famille des pyréthrinoïdes de synthèse), le 3-Iodo-2-propynyl but yI carbamate (IPBC, fongicide/bactéricide appartenant à la famille des carbamates), ainsi que le propiconazole et le tébuconazole (fongicides de la classe des triazolés). Or, pour des raisons historiques, les scieries de résineux sont souvent implantées en tête de bassin, en bordure de petits cours d'eau particulièrement vulnérables. Le présent travail a pour objectif de contribuer à une meilleure compréhension des perturbations engendrées par ces installations de traitement du bois sur les milieux aquatiques environnants, en particulier vis-à-vis des populations de Gammarus pulex et Gammarus fossarum (Crustacé, Amphipode). Dans cette perspective trois approches complémentaires ont été développées. L'approche chimique a permis de qualifier certains processus liés à l'adsorption d'une matière active fréquemment employée dans le traitement du bois, le propiconazole, sur un matériau standard, le charbon actif. Cette approche a aussi eu pour objet le développement d'une méthode de dosage des pesticides étudiés dans la matrice sédimentaire. Les limites de détections atteintes sont comprises entre 0,3 et 3,3 [micron]g. Kg-1. Cette méthode a été utilisée. Avec succès pour caractériser le niveau de contamination sédimentaire d'un système aquatique situé à proximité d'une aire de traitement du bois. La présence récurrente de produits de préservation du bois a ainsi été observée sur plusieurs kilomètres à l'aval des installations de traitement. L'approche hydro-écologique a permis de quantifier l'impact in natura d'aires de traitement du bois sur des populations de G. Pulex et G. Fossarum. Une sévère réduction des densités et une altération du cycle de vie de ces espèces ont ainsi pu être observées, cela de façon durable et sur plusieurs kilomètres à l'aval des installations de traitement. De plus, les densités d'adultes ont été réduites dès l'aval proche, alors que les densités de juvéniles le sont sur une plus grande distance. L'approche écotoxicologique a rendu compte de la sensibilité de \es deux espèces à des matières actives parmi les plus employées dans le cadre du traitement du bois. La létalité de ces substances en mélange pour G. Pulex est renforcée par une synergie opérant à certains ratios et par la présence d'adjuvants dans les solutions de traitement commerciales. De plus, des variations de sensibilité des populations ont été observées selon leur origine géographique et le stade de développement considéré, les juvéniles étant plus sensibles que les adultes. La présente étude permet de mieux appréhender les réponses des populations de G. Pulex et G. Fossarum aux perturbations engendrées par les aires de traitement du bois. La vulnérabilité de ces organismes est discutée, en particulier dans des environnements contaminés par des concentrations en produits de traitement du bois proches des limites de détection de la méthode de dosage développée. L'utilisation de ces taxons à des fins bioindicatrices, notamment en relation avec d'autres taxons macrobenthiques, est également discutée, de même que les perspectives de développement du présent travail.
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Mohamed, W. F. A. "Palladium uptake and its effect on behavioural and molecular markers in the freshwater shrimp Gammarus pulex." Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/28316/.
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The expanded use of platinum group elements (PGEs), platinum (Pt), palladium (Pd), and rhodium (Rh), in automobile catalysts has led to increased levels of these metals in aquatic environments. However, data regarding acute toxicity and the sublethal effects of these metals on aquatic biota are limited. This study aimed to explore the response of the freshwater amphipod Gammarus pulex to PGEs. Investigations included the 96 LC50 test and several behavioural (vertical movement and feeding activity) and biochemical (acetylcholinesterase (AChE); osmoregulation; 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) reduction; reduced glutathione (GSH); glutathione-S-transferase (GST); thiobarbituric acid reactive substances (TBARS); heat shock proteins (HSPs) and protein phosphorylation) endpoints. Pd caused a significant reduction in the survival of G. pulex with a 96 h LC50 of 0.52 mg/L (4.89 μM). Pt or Rh increased the survival of G. pulex exposed to Pd. However, this was not associated with reduced Pd uptake. Exposure for 24 h to 0.5 mg/L Pd (4.69 μM) significantly decreased the vertical movement (64%) and feeding activity (95%) of G. pulex. However, lower Pd concentrations (≥0.25 mg/L (2.3 μM)) took 72 h to induce significant inhibition in feeding activity (50%). AChE activity was significantly increased (40%) following 72 h exposure to 0.5 mg/L Pd. GST activity was significantly inhibited (≥32%) following 72 h exposure to ≤0.25 mg/L Pd. The concentration of GSH was significantly increased (22 and 35%) following 72 h exposure 0.1 (0.94 μM) and 0.5 mg/L Pd2+, respectively. Exposure to ≤0.1 mg/L Pd caused a significant decrease (≤27%) in MTT reduction and significant increase (≤70%) in HSP60 content in mitochondrial extract (pellet) after 72 and 24 h exposure, respectively. The reactivity of anti-phosphoserine bodies with protein bands corresponding to 245 kDa in the pellet was significantly increased (38%) by exposure of gammarids to 0.5 mg/L Pd. Exposure to 0.1 mg/L Pd significantly increased (32%) the intensity of a 30 kDa anti-phosphothreonine reactive protein band in the post-mitochondrial extract, but higher Pd doses had no effect. In conclusion, this study provides original data suggesting the mitochondria as a main target of Pd toxicity. Further studies of Pd toxicity, under both laboratory and field conditions, are needed including the effect of long-term exposure to low Pd concentrations.
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Ash, Nicholas Watson. "Fungal determinants of feeding preference for the two stream detritivores Gammarus pulex (L.) and Asellus aquaticus (L.)." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559792.
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Graca, Manuel Augusto Simoes. "Observations on the feeding biology of two stream-dwelling detritivores : Gammarus pulex (L.) and Asellus aquaticus (L.)." Thesis, University of Sheffield, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244076.
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Ennis, Marilyn. "Parasite effects on the feeding behaviour and functional response of the invasive amphipod Gammarus pulex (Crustacea; Amphipoda)." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705915.
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Parasites can structure communities and may impact on resource competitive interactions in novel communities. The amphipod Gammarus pulex is invasive in Ireland and in low land river stretches has displaced the native congener Gammarus duebeni celticus. Parasitism may facilitate invasion success by the more efficient use of resources. The functional response (the relationship between prey density and prey consumption) is a means of predicting the likely impact of an invader. In this thesis parasitism by two different acanthocephalan parasite species (Echinorhynchus truttae and Polymorphus minutus) elevated the functional response of G. pulex with either Baetis rhodani or Asellus aquaticus prey. Analysis of prey body part consumption in Baetis rhodani prey by E. truttae parasitised G. pulex revealed that parasitised predators consumed more prey material, partially consumed more prey but consumption distribution was not related to body part. In turn, partial prey consumption may reduce handling time in parasitised predators and may provide a mechanistic explanation for the elevation of functional response parameters. Unconsumed prey provide an additional food source for consumers that are too small or slow to capture larger prey, with consequences for nutrient cycling within freshwater communities. With regards to physiological parameters, non-starved parasitised and unparasitised G. pulex had similar haemolymph protein levels whereas starvation significantly elevated the haemolymph protein level of parasitised G. pulex compared to unparasitised animals. This finding suggested parasite upregulation of host protein resources to compensate for depletion of host haemolymph protein levels during starvation. Additionally, long term starvation did not affect survival rate in parasitised or unparasitised G. pulex but appeared to impact on parasite length in parasitised hosts.. Parasitised invasive predators such as G. pulex may therefore possess traits that allow more efficient use of resources compared to native congeners, which may facilitate and explain the invasion success of this species.
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Vignoles, Philippe. "Toxicite du benzamido-2 nitro-5 thiazole et de onze derives sur lymnaea peregra ovata muller, gammarus pulex pulex l. Et euglena gracilis klebs. Relations structure-activite quantitatives." Limoges, 1990. http://www.theses.fr/1990LIMO0107.
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L'efficacite in vitro de douze derives du benzamido-2 nitro-5 thiazole substitues sur le cycle benzenique a ete etudiee sur trois especes: lymnaea peregra ovata, gammarus pulex pulex et euglena gracilis. Les resultats obtenus ont ete compares a ceux obtenus avec un produit de reference, le niclosamide. La determination: 1) de la cl50 (concentration de toxique pour laquelle on obtient 50% de mortalite) chez l. P. Ovata et g. P. Pulex, et 2) de la cl50, de la ci50 (concentration de toxique reduisant de 50% la croissance) et de la camax (concentration provoquant une activation maximale de la croissance) chez e. Gracilis montre que les produits les plus efficaces possedent un substituant halogene en position meta et sont generalement bisubstitues. Une etude des relations structure-activite quantitative montre que la toxicite augmente avec la lipophilie et diminue generalement avec l'effet attracteur des substituants<br>The studies presented in this thesis focused on the in vitro effectiveness of twelve 2-benzamido-5-nitro thiazole (BNT) derivatives substituted on the benzene ring on three species: Lymnaea peregra ovata, Gammarus pulex pulex and Euglena gracilis. The results obtained were compared with those provided by a reference product, niclosamide. The intoxication of L. P. Ovata and G. P. Pulex by the derivatives of BNT or niclosamide was studied at first. Most L. P. Ovata showed an emersion during the first contact with one or the other of the toxic products and this process was even faster when the product was concentrated. Subsequent retraction of the animal into its shell usually preceded its death. The reproductive activity of the snail was disturbed with a decrease in the number of egg-masses. The amplitude of G. P. Pulex displacements only decreased at high concentrations of toxic; the movements of its pleopods were then increased. The determination of the LC50 was performed with the 13 products in both species. The value of this parameter gradually decreased in inverse proportion to the exposure time and tended towards a zero limit. The most effective products had a halogenated substituent in the meta position and were generally bisubstituted. The increase in toxicity over time was lower in G. P. Pulex than in L. P. Ovata. The toxicity of BNT was close to that of niclosamide. The second part of this work focused on the intoxication of E. Gracilis by BNT derivatives or niclosamide. The products acted by inducing a delay in cell growth, a decrease in the maximum number of algae per millilitre and causing their death. The cultivation of algae at pH 3. 5 and at pH 7. 2 was used to study the effectiveness of the protonated and neutral forms of the molecules. The products showed a difference of activity according to the pH: their toxicity could be higher in an acid medium than in a neutral medium. The effectiveness of BNT derivatives was estimated using three parameters: LC50, IC50 and ACmax. If the LC50s and IC50s are considered in relation to exposure time, we have noted a fall to a minimum with a subsequent maintenance at this minimum or an increase. The most effective products were usually those that had a substituent in the meta position. In addition, these derivatives were generally bisubstituted. The toxicity of niclosamide was generally lower than that of the most effective BNT derivatives. ACmax values were close to the LC50 values of L. P. Ovata or G. P. Pulex. The results obtained with the three species enabled to study the relationships between the activity of the products and their structure. The toxicity parameters (LC50 or IC50) were expressed in relation to the physicochemical parameters of the molecules (octanol/water partition coefficient, alkaline hydrolysis rate constant) or the parameters of the substituents (π of Hasch, σ of Hammett). The results showed that the toxicity increased with lipophilicity and generally decreased with the electro-attractive effect of the substituents, except for E. Gracilis at acid pH where the attractive effect increased the toxicity. The pKa did not intervene in these relations, whatever the species studied
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Warwick, Oliver William Tindle. "The use of a biomarker to assess the effect of xenobiotic exposure on the freshwater invertebrate Gammarus pulex." Thesis, University of Sheffield, 1997. http://etheses.whiterose.ac.uk/10191/.
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Contamination of freshwaters is of concern because of its effect on ecosystem health. The effect of contamination can be assessed at all levels of biological organisation, from the ecosystem level to the molecular level. At the biochemical level, enzymes that are involved in the detoxification of organic chemical contaminants are useful as markers of contaminant exposure as they are often one of the first systems to respond to chemical exposure. Furthermore, changes in the activity of these enzymes may be indicative of effects at higher levels of biological organisation. In this study, the use of the detoxification enzyme glutathione stransferase (E. C. 2.5.1.18) (GST) in the freshwater invertebrate Gammarus pulex (Crustacea: Amphipoda), as a biomarker of organic xenobiotic exposure and effects was assessed. Toxicant induced changes in GST activity were related to changes in energy status and physiological energetics. A GST assay was developed that allowed the rapid analysis of GST activity in up to ninety individual animal samples simultaneously. Optimum sample handling and assay conditions were determined for the assay of GST in G. pulex, and extrinsic factors (e. g. environmental temperature, feeding and holding conditions) and intrinsic factors (e. g. body size), affecting variability of GST activity in G. pulex were assessed The effect of exposure to the organic xenobiotics lindane( an organochlorinein insecticide) and alcohol ethoxylate( a non-ionic surfactand detergent)on GST activity in G.pulex was described. The magnitude and duration of the response of GST activity to exposure to both chemicals was assessed under laboratory conditions and with alcohol ethoxylateu, sing outdoor artificial streams. The use of GST as a marker of pesticide exposure in field populations of G. pulex that were subject to pesticide contamination was studied in comparison with animals from non-contaminated, reference sites. The differences in GST activity between animals from a contaminated site and clean site were investigated by short-term and long-term exposure to lindane in the laboratory. Changes in energy status and physiological energetics were investigated in G. pulex on exposure to lindane by measuring glycogen concentration and scope for growth. Measuring these parameters on short-term and long-term exposure to lindane allowed the sensitivity of these responses to be related to the GST response and allowed the energetic cost of exposure to be assessed. It was concluded that increase in GST activity may providea rapid and sensitive biomarker of xenobiotic exposure in the short-term and in populations subject to pesticide contamination. The affect on GST activity may be indicative of effects at higher levels of biological organisations, such as scope for growth and glycogen concentration However, GST activity is affected by a variety of intrinsic and extrinsic factors and should therefore be used only asp art of a comparative study. Because of the transient nature of the GST response in situ assessments should be based on 24-hour exposure periods.
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Elwahaishi, S. S. "The effect of the sheep dip pesticide diazinon on behavioural and molecular markers in the freshwater shrimp Gammarus pulex." Thesis, Nottingham Trent University, 2012. http://irep.ntu.ac.uk/id/eprint/199/.
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The purpose of this research was to determine the effects of the organophosphorothioate pesticide diazinon, its metabolite diazinon oxon and diazinon in a commercial formulation on the freshwater amphipod Gammarus pulex. It was found that diazinon in the commercial formulation was significantly more toxic to G. pulex than diazinon oxon, which in turn was significantly more toxic than diazinon. In non-lethal ecotoxicity assays, 24 h exposure to diazinon and diazinon in the commercial formulation significantly inhibited the vertical movement of G. pulex, whereas diazinon oxon had no significant effect. Inhibition of feeding was observed, with diazinon in the commercial formulation causing the most reduction, then diazinon to a lesser extent, whereas diazinon oxon had no significant effect. Only diazinon oxon caused a significant inhibition of acetylcholinesterase (AChE) activity in vitro. However, only diazinon and diazinon in the commercial formulation caused a significant inhibition of AChE activity following in vivo exposure. The levels of small heat shock protein (sHSP) and HSP 90 in post-9,000g supernatant samples were significantly increased by exposure to diazinon and the commercial diazinon formulation. Only diazinon significantly increased the level of HSP 70 in the supernatant. In contrast, diazinon and diazinon in the commercial formulation significantly increased the level of HSP 70 in 9000g pellet samples. Only diazinon in the commercial formulation significantly increased level of HSP 90 the in pellet sample. There was no significant effect of these agents on HSP 60 levels. Western blotting analysis of 10 % gels showed increased phosphotyrosine content in 51 and 75 kDa bands and increased phosphoserine and phosphothreonine content in the 75 kDa band following exposure to diazinon and diazinon in the commercial diazinon formulation. In contrast, a 51 kDa anti-phosphoserine reactive band only showed a significant increase after exposure to diazinon andIVdiazinon in the commercial diazinon. Analyses by 2D-PAGE found that a small numbers of low abundance proteins had altered levels in the 9000g supernatant sample after exposure to diazinon. However, the levels were too low to allow identification by mass spectrometry (MS). In conclusion, behavioural assays and biomarkers can be employed as useful and reliable bioindicators of environmental contamination.
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Vellinger, Céline. "Effets d'expositions métalliques simples ou multiples à différentes températures chez Gammarus pulex : approche multi-marqueurs et perspectives en bioévaluation." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0287/document.
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Les contaminations multiples par des métaux et métalloïdes menacent la structure et le fonctionnement des écosystèmes aquatiques. Pourtant, les mécanismes d'action des polluants, leurs interactions et leur toxicité dans un contexte de réchauffement climatique sont encore peu abordés. Parallèlement, nous avons un besoin urgent de marqueurs d'alerte (i.e., précoces, sub-létaux) des effets de ces substances. Par ailleurs, une attention croissante est actuellement portée au protéome des êtres vivants, considéré comme une entité dynamique, modifié par les conditions du milieu. Dans ce contexte, nous avons travaillé en laboratoire avec comme espèce modèle le crustacé amphipode Gammarus pulex avec trois objectifs: (1) évaluer les effets de deux éléments métalliques (cadmium et arséniate) seuls ou en interaction sur des organismes exposés en conditions contrôlées, (2) appréhender les effets de la température en tant que facteur confondant potentiel des réponses mesurées, et (3) rechercher l'existence d'une réponse singulière potentielle du protéome d'individus exposés aux éléments métalliques seuls ou en mélange ; à plusieurs températures. Il s'agissait donc à la fois de réaliser une analyse diagnostique susceptible de fournir des marqueurs d'intérêt aptes à révéler précocement un stress chimique et de dresser les bases d'une approche pronostique permettant de mieux prédire les conséquences à l'échelle individuelle d'une dégradation anthropique du milieu<br>Multiple metal and metalloid contaminations impair aquatic ecosystem community structure and functioning. However, the mechanistic understanding of individual pollutant toxic effects, but also of their interaction effects in a "global warning" context are still rarely tackled. However, aquatic ecosystem managers have an urgent need of early warning indicators (i.e. early, sub-lethal) of toxicant effects. Recently, an increasing attention has been turned to studies of the proteome of species/populations, which is considered as a dynamic entity modified by environmental conditions. In this context, we have worked with a model organism, Gammarus pulex (crustacea, amphipoda), under laboratory controlled conditions. Three objectives have been defined: (1) assessing the single and combined effects of two metals (i.e. arsenate and/or cadmium), (2) understanding the potential confounding effect of temperature on measured physiological and behavioural responses of gammarids and (3) investigating the existence of a singular response of the proteome of individuals exposed to different single or combined metal concentrations, at several tested temperatures. The major goals were first applying a diagnostic analysis to provide valuable biomarkers early indicating metallic stress, and second developing the foundations for a prognostic approach better predicting the organismal consequences of toxic contaminations due to the anthropogenic degradation of aquatic ecosystems
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Poulton, Madeline June. "Toxic effects of freshwater pollutants on the survival, behaviour and reproduction of Gammarus pulex (L.) and Asellus aquaticus (L.)." Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320266.
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The toxic effects of cadmium on aspects of the survival, behaviour and reproduction of Gammarus pulex and Asellus aquaticus are described in some detail. Some of the laboratory procedures were validated in field experiments. The presence of the parasites Pomphorhynchus laevis and Echinorhynchu_s1truttae does not modify the toxicity of cadmium (0.01-1.0 mgl ) to their intermediate-Fost G. pu7ex. Pretreatment for 24 hours with 0-47 μgl cadmium alters the distribution of separation times when precopula pairs of G. pu7ex are disrupted by the invertebrate anaesthetic 2- phenoxyethanol. Precop1la is directly disrupted by exposure to cadmium (0.1-12.7 mgl )_ýut recovery can follow. Pretreatment with cadmium (3-140 μgl ) for 24 hours, of similarly sizeci male G. pulex and subsequent exposure to 0.13 and 2.23 μgl while in competition for access to a female may increase tolerance and enhance reproductive success, or initiate irreversible toxic effects and impair competitive ability. Exposure of female G. pulex-1to 2.0 and 9.6 μg1 , and female A. aquaticus to 40.2 pgl cadmium pre-fertilization reduces their fecundity. Brood development times of G. pulex and A. aquaticus exposed to 2.1 and 12.4 μg1-1 cadmium postfertilization are extended by 2 and 2.7 days respectively. The embryonic development and abortion during brooding are described in detail for A. aquaticus. An explanation of reduced final brood size in Asel7us is Postulated. Growth of juveniles of both test species exposed during brooding is assessed. Single and repeated 24 hour field simulations of acidic deposition demonstrate increased host sensitivity of G. pulex infected with P. 7aevis. The effects of low pH and elevated aluminium concentrations are mitigated to some extent by liming. Six hour field simulations of the individual components of farm waste demonstrated that infected gammarids were more susceptible under conditions of low dissolved oxygen than uninfected conspecifics.
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Choudhury, Md Maidul Islam. "Does an evolutionary change in the water sowbug Asellus aquaticus L. alter its functional role?" Thesis, Linköpings universitet, Ekologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-74766.
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The ecology behind evolutionary diversification is a well studied area of research, whereas the effects of evolution on ecosystems get little attention. In line with ecological theory, evolutionary diversification of a species could influence different ecosystem aspects such as food web composition, energy flow, nutrient cycling etc. The main objective of this study was to investigate whether two diverging ecotypes (reed and chara) of Asellus aquaticus differ regarding their role in two aquatic ecosystem processes: decomposition of terrestrial leaves and grazing of periphyton. Their role in ecosystem process as well as treatment effects on fitness, measured as growth and survival, were investigated in a laboratory experiment with various levels of intra-specific competition and inter-specific interactions with the amphipod Gammarus pulex. The isopods were collected from two Swedish lakes: Lake Tåkern and Lake Fardume. These two lakes represent different history of ecotype divergence. The experimental design consisted of 2-L aquaria, each providing elm leaves (Ulmus glabra), oak leaves (Quercus roburleaves) and periphyton as food sources. Ten treatments with five replicates were applied for each lake and the experiment lasted for four weeks. The study showed that there was no significant difference between chara and reed ecotype in their functional role. However, the rate of ecosystem processes per individual decreased in competitive interactions. In high density, decomposition per dry weight consumer was low and total algae biomass was high at the end of four weeks due to intra-specific competition. Moreover, ecosystem processes were lowest in inter-specific competition between Gammarus pulex and each ecotype. Present study also shows that ecotypes from the different lakes, having different history, had different responses to mortality and growth.
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Foucreau, Natacha. "Étude des réponses écophysiologiques et fonctionnelles de populations de l'organisme clé Gammarus pulex (crustacea, Amphipoda) dans un contexte de changement climatique, au sein de la vallée du Rhône." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10256/document.
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L’étude des conséquences du réchauffement climatique sur les écosystèmes aquatiques est devenue un enjeu majeur pour la recherche. Nous avons mesuré l’impact de la température des eaux douces et du changement de végétation riparienne associé au climat sur six populations de Gammarus pulex (Amphipode) vivant au nord ou au sud de la vallée du Rhône (France). Ce crustacé, largement répandu dans les eaux douces européennes, est considéré comme une espèce clé pour le fonctionnement des écosystèmes aquatiques, car, en dégradant la litière de feuilles provenant de la ripisylve, il favorise son utilisation par d’autres invertébrés. Nos résultats sur l’effet de la température sur les réserves énergétiques, la consommation d’oxygène et la survie, suggèrent que la fenêtre thermique optimale est décalée de 2-3°C entre les gammares du nord et ceux du sud. L’investissement reproducteur varie saisonnièrement, avec des stratégies différentes selon l’origine des femelles. La provenance des feuilles (méditerranéenne/continentale) influence moins leur conditionnement et la vitesse de décomposition que leur dureté initiale. Une hausse de température accélère le conditionnement et la digestion des feuilles mais influence peu leur dégradation. Nos résultats montrent que des adaptations en bordure d’aire de distribution peuvent modifier la réponse des organismes aquatiques face aux changements climatiques. De plus, un changement de la nature des litières lié au réchauffement pourrait modifier la disponibilitédes ressources trophiques au cours des saisons et ainsi le fonctionnement des écosystèmes<br>The study of global warming consequences on aquatic ecosystems has become amajor issue in current scientific research. We measured the impact of water temperature and the climate-related change in riparian vegetation on six populations of Gammarus pulex (Amphipoda) living in the North and in the South of the Rhône River valley (France). This crustacean, widely distributed in European freshwaters, is considered as a key species for the freshwater ecosystems functioning as it degrades the leaf litter from the riparian area, thus favouring its subsequent use by other invertebrates. Our results of temperature effect onenergy stores, oxygen consumption, and survival suggest that the optimal thermal window shifts from 2-3°C between northern and southern gammarids. Females’ investment into reproduction changes through seasons, with different strategies according to their geographical origins. Concerning the functional point of view, the leaf litter origin(Mediterranean/continental) less influences the conditioning of leaves and the decomposition rate than their initial toughness. An increase in water temperature accelerates the conditioning and the enzymatic digestion of leaves (in gammarids guts) but slightly influences their degradation by this crustacean. Our results show that adaptations at the limit of the species geographical distribution area can change the response to climate change in aquatic organisms. Moreover, a change in the type of the leaf litter could modify the availability of trophic resource through seasons and hence the ecosystem functioning
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Aronsson, K. Andreas. "Effects of wood ash on freshwater organisms and aquatic forest ecosystems." Doctoral thesis, Sundsvall : Mittuniversitetet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-36.
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