L'objectif général de ce travail est l étude de la toxicité chronique du chlordane chez un crustacé d eau douce afin d évaluer le risque de ce pesticide sur les organismes aquatiques. Pour ce faire, nous avons choisi le cladocère Daphnia magna comme modèle d étude, à cause de son rôle clé dans la chaîne trophique, sa sensibilité et son cycle de vie qui est mis à profit pour étendre le test de reproduction classique utilisant une seule génération saine sur deux générations successives. Le test chronique (21j) a donné une concentration sans effet observée (NOEC) sur tous les paramètres de 0,18 g/L qui constitue une donnée importante dans l évaluation du risque du chlordane pour le milieu aquatique. L exposition de D.magna aux fortes concentrations de chlordane a induit des malformations et l apparition de mâles chez la descendance. L étude de la bioaccumulation a montré le fort potentiel de bioaccumulation chez D.magna avec un facteur de bioaccumulation de 244000 (poids sec) après 40 jours d exposition à la NOEC. L étude de la toxicité du chlordane sur deux générations successives (F0 et F1) a montré que celle-ci augmente avec la concentration et le temps d exposition. Ainsi, la génération F1 est plus sensible que la génération F0 et la population de la génération F1 issue de la 5ème ponte s est montrée plus sensible que la génération F1 issue de la 2ème ponte. L étude de la capacité de récupération des daphnies de la génération F1, après leur transfert dans un milieu propre a montré l absence d une récupération totale aux plus fortes concentrations testées. La comparaison de la sensibilité de D.magna à un autre crustacé C.dubia suite à une exposition chronique au chlordane a souligné l intérêt de l utilisation de ce dernier dans l étude de la toxicité chronique des polluants persistants à condition de prolonger la durée du test de 7 à 14 jours. L ensemble de ces résultats souligne l intérêt du modèle D.magna dans l étude de la toxicité chronique des polluants persistants et de leurs éventuels effets sur les différents processus de reproduction. / This research aimed at studying the toxicity of chlordane in freshwater crustacean in order to evaluate the risk of this pesticide on aquatic organisms. We choice Daphnia magna as model of study, because her key role in trophic chain, her sensitivity and her short life cycle that are exploited for extended the classic reproduction test using only one healthy generation on two successive generations. In the chronic test (21d), a concentration without observed effect (NOEC) on all parameters of 0.18 g/L was obtained. The exposition of D.magna to the strong concentrations of chlordane led the malformations and the apparition of males at the progeny. The study of the bioacumulation showed the high potential of bioaccumulation at D.magna with a factor of bioaccumulation of 244 000 (dry weight) after 40 days of exposition to the NOEC. The study of the toxicity of the chlordane on two successive generations (F0 and F1) showed that this one increases with the concentration and the time of exposition. So, the F1 generation is more sensitive than the F0 generation and the population of the F1 generation 5th brood is more sensitive than the one of the F1 generation 2nd brood. The study of the recovery of the daphnids after their transfer in clean water showed their capacity to restore reproduction only for the low doses. The comparison of the sensitivity of D.magna in another crustacean C.dubia following a chronic exposition to chlordane underlined the interest of the use of C.dubia in the study of the log term toxicity of the persistent pollutants under the condition to prolong the duration of the test from 7 to 14 days.The present work highlights the interest of our model in the study of the chronic toxicity of persistent pollutants and their possible effects on the different processes of reproduction

The active synthetic constituent of oral contraceptives 17α- ethinylestradiol (EE2) and its natural steroidal estrogen analogues are being released into the aquatic environment mainly via wastewater treatment plants (WWTPs). Although steroidal estrogens have been frequently reported in very low concentrations in the environment, they have been placed at the top of the list of endocrine disrupting chemicals (EDCs) for their high estrogenic activity in non-target aquatic species like fish and frogs. Almost 30 years worth of intensive research has moved the problem of endocrine disruption in the aquatic environment from being a hypothesis to a well-known cause-and-effect story. However, the fate and effects of many pharmaceuticals, including EE2, remain poorly understood. Thus, the main objective of this thesis was to investigate EE2 bioaccumulation in fish by field and laboratory studies. An optimized sample preparation and analytical method protocol was achieved to detect EE2 in its biologically active form in whole fish tissue at trace levels (ng/g). Shorthead redhorse suckers (ShRHS) (Moxostoma macrolepidotum) collected in proximity to a WWTP in the St. Clair River have significantly accumulated EE2 with an average of 1.5 ng/g. EE2 bioaccumulation was limited to fish exhibiting intersex and with induced vitellogenin (VTG). EE2 was absent in fish from a reference site. Positive correlations between EE2 and lipid content as well as "15N supported the hypothesis of EE2 bioaccumulation in wild ShRHSs. A wider survey was carried out to explore patterns of EE2 bioaccumulation in the pelagic and benthic food-wed of the St. Clair IV River, Ontario. In the WWTP effluents and nearby surface waters, EE2 levels were extremely low and below our method detection limits. All of the seven sampled species from different trophic levels and the sediment samples collected from the impacted sites and the reference sites did not have any measurable EE2 concentrations. A laboratory controlled study where male goldfish (Carassius auratus) were exposed to EE2 via water versus food demonstrated that fish can rapidly accumulate EE2 by both routes of exposure. The uptake constant for water was 45 h-1 and the bioconcentration factor for EE2 in fish was 377. The fast uptake rate of EE2 via water coincided with a much slower elimination rate constant of 0.0786 h-1. The assimilation efficiency of 0.106 for EE2 by goldfish was determined by EE2 dietary exposure, which was used to predict EE2 accumulation under different exposure scenarios. The work presented here was the first demonstration of EE2 bioaccumulation in wild fish and the first to model EE2 bioaccumulation from water and dietary exposure in laboratory-exposed fish.

Insectivorous bats have been found to have unusually high levels of mercury. While broad geographic scale studies have investigated factors contributing to mercury bioaccumulation in bats across Canada, studies investigating differences in regional scale bioaccumulation and the contributing factors remain scarce. Here, I comprehensively investigate the bioaccumulation of mercury in two insectivorous bats, the big brown bat (Eptesicus fuscus) and the little brown bat (Myotis lucifugus), collected over a period of ~20 years along the St. Lawrence River in Eastern Ontario, parts of which are historical hotspots of mercury, to address two objectives: First the determination of biological and environmental factors, including dietary sources, contributing to reported patterns of fur total mercury bioaccumulation, and second the investigation of DNA-based biomarkers as potential tools to assess internal tissue-responsiveness to mercury exposure, specifically global DNA methylation and expression levels of mitochondrial DNA. With regard to factors determining fur total mercury concentration in Eastern Ontario bats, significant differences between species exist, as higher concentrations were found in big brown bats compared to little brown bats. Sex contributed to differences in fur total mercury, however in a species-specific manner. Male fur contained higher total mercury concentrations compared to females in big brown bats, but not little brown bats. Female reproductive status differentially affected fur mercury concentrations between both species, reducing concentrations in pregnant little brown bats, while significantly increasing concentrations during lactation in big brown bats. Finally, fur total mercury concentration in adults was higher than that of juvenile bats (< 1 yr). To address the hypothesis that aquatic emerging and terrestrial insect diets differentially contribute to Eastern Ontario bat mercury concentration, I used stable isotope analysis and telemetry approaches and caught aquatic and terrestrial insects. While higher total mercury was identified in aquatic compared to terrestrial insects, a high degree of variability in the isotope signature in insects and bats in Eastern Ontario did not allow to fully address this hypothesis. However, data pointed to a more specialized diet in big brown bats compared to a more generalist diet in little brown bats as well as a sex-specific correlation between dietary source and fur total mercury concentration in little and big brown bats. The evaluation of potential epigenetic and mitochondrial DNA-level molecular biomarkers in kidney, brain and liver (DNA methylation and assessment of relative mitochondrial DNA copy number) did not reveal significant correlations with fur total mercury concentrations. This may suggest that the mercury concentrations measured in this study were not high enough to elicit these specific DNA level responses or they do not represent relevant biomarkers of environmental methylmercury exposure, at least in big brown bats. Overall, this thesis contributes to our understanding of regional variability in fur total mercury concentration within and between Eastern Ontario bat species. These findings provide important insights for future targeted investigations of the contribution of aquatic emerging and terrestrial insect dietary sources on the one hand and underline the importance of accounting for regional variability in more global scale comparisons of bat mercury bioaccumulation on the other.

Les organochlorés(OC) sont des composés chimiques qui ont été utilisés dans plusieurs secteurs industriels, notamment en santé publique comme insecticides jusque dans les années 70 au Canada et aux États-Unis. Ces composés sont connus comme étant lipophiles, donc ils ont tendance à s'accumuler dans le tissu adipeux et causer des problèmes de santé au niveau des systèmes endocrinien et immunitaire. La meilleure porte d'entrée des OC dans l'organisme est la nourriture d'origine animale c'est-à-dire la viande, le poisson, les produits laitiers et les œufs. Cela suggère que les végétaliens seraient moins pollués que les omnivores et auraient donc moins de problèmes thyroïdiens et par conséquent un métabolisme énergétique plus élevé. Par contre, lors d'une première étude, nous n'avons pas observé de différences significatives entre le groupe témoin et le groupe de végétaliens en ce qui a trait aux concentrations plasmatiques en organochlorés. Nous avons toutefois observé une corrélation négative entre la concentration plasmatique en organochlorés des deux groupes confondus et la concentration en hormones thyroïdiennes. Une autre étude rapportée dans ce mémoire montre qu'il y a des concentrations détectables de composés organochlorés dans les produits laitiers mais seulement dans les produits les plus gras.

Natürliche Biofilme von zwei urankontaminierten Standorten, dem ehemaligen Uranbergwerk in Königstein (Sachsen) und dem Gebiet der ehemaligen Aufstandsfläche der Gessenhalde (Thüringen), wurden in dieser Arbeit näher untersucht. An beiden Standorten konnte in den Minenwässern die hochmobile, gelöste Uranspezies Uranylsulfat (UO2SO4) als dominierend nachgewiesen werden. Aufgrund der Instabilität vieler kommerzieller Fluoreszenzfarbstoffe bei niedrigen pH-Werten war eine gezielte Anfärbung der Mikroorganismen in den sauren Biofilmen nicht möglich, ohne den pH-Wert der Biofilmproben anzuheben, was die Probenchemie maßgeblich verändert. In Kooperation mit der Firma DYOMICS (Jena, Deutschland) wurden neue, kommerziell nicht erhältliche, säurestabile Farbstoffe erstmals hinsichtlich ihrer Eignung zur Anfärbung von Mikroorganismen in sauren Biofilmen ohne Veränderung des pH-Wertes sowie der sonstigen Probenchemie getestet. Die neuen Farbstoffe DY-601XL, V07-04118, V07-04146 und DY-613 zeigten eine Eignung für solche Färbungen, da sie eine intensive Anfärbung der Mikroorganismen bei niedrigen pH-Werten unter pH 3 – 4 herbeiführen und außerhalb des Emissionsbereiches von Uran fluoreszieren. In dieser Arbeit wurde die Fähigkeit von Euglena Mutabilis-Zellen zur Bioakkumulation des Urans im pH-Wertbereich 3 – 6 in den Hintergrundmedien Natriumperchlorat (9 g/l) oder Natriumsulfat (3,48 g/l) an lebenden Zellen untersucht. Unabhängig vom Medium konnte bei sauren pH-Werten um pH 3 – 4 über 90 % des vorgelegten Urans aus den Probelösungen abgetrennt werden. Die Speziation des an den Euglena-Zellen akkumulierten Urans, wurde mittels laserinduzierter Fluoreszenzspektroskopie (LIFS) untersucht. Es zeigte sich, dass unabhängig vom Hintergrundmedium, Lebenszustand und pH-Wert eine vergleichbare neue Uranspezies an den Zellen gebildet wird. Durch den Vergleich der Daten aus den LIFS-Messungen mit Referenzwerten, konnte die gebildete Uranspezies auf eine Anbindung durch (organo)phosphatische und/oder carboxylische funktionelle Gruppen eingegrenzt werden. Mit Hilfe der zeitaufgelösten FT-IR-Spektroskopie konnte die carboxylische Anbindung des Urans an toten Zellen nachgewiesen werden. Ein Ausschluss der (organo)phosphatischen Komplexierung konnte jedoch mit dieser Methode nicht geführt werden. Untersuchungen zur Lokalisation des Urans an bzw. in den Zellen, mittels der gekoppelten CLSM/LIFS-Technik zeigten erstmals ein Indiz für die intrazelluläre Akkumulation von Uran in den lebenden Zellen. Ergänzende TEM/EDX-Messungen bestätigten die intrazelluläre Aufnahme und belegen eine Akkumulation in runden bis ovalen Zellorganellen, bei denen es sich vermutlich um Vakuolen oder Vakuolen-ähnliche Vesikel handelt. An den toten Zellen konnte mit diesen Methoden kein Uran detektiert werden. Dies lässt auf eine passive, homogen verteilte Biosorption des Urans an die verfügbaren Bindungsplätze an der Zelloberfläche der toten Biomasse schließen.

M.Sc. (Zoology) / Blood samples were obtained from 42 Cape (Gyps coprotheres) Vultures during the period 1990 to 1991. Nestlings were sampled at two natural localities namely the Scheerpoort and Manoutsa colonies. Samples from captive birds ranging in age from immature to mature were obtained from four locations which include the Johannesburg Zoo, Tygerberg Zoo, De Wildt Cheetah Research and Breeding Station and World of Birds. The main objective of the study was to describe the population genetic structure of G. coprotheres by means of a protein electrophoretic examination. The optimum electrophoretic conditions were determined for maximum resolution of the protein systems examined. Allele frequency data assessed at 34 structural gene loci were obtained. As measures of variability, the perc~ntage polymorphic loci and average heterozygosity were calculated for the Cape vulture and values obtained were 11.76\ and 0.021 respectively. Both of the latter values are less than half the values reported for the majority of other avian species. The electrophoretic data were utilised in two population genetic simulation programmes and it was determined that the variation present in the populations of G. coprotheres studied may disappear within the next 35 generations. The blood samples were also subjected to a toxicological examination. Concentrations of DDT and its derivatives were measured by gaschromatographic analyses. Biocide levels were detected in ppb and adjusted to ppm by a conversion factor of 150. Quantifiable levels of DDT, DOD and DOE were detected in 72.4\, 60.0% and 89.7% of the individuals respectively. DOE is one of the major metabolites of DDT and the discussion was focused on levels thereof.

La baie de Marennes Oléron, premier site ostréicole français, est influencée par la pollution polymétallique historique de l’estuaire de la Gironde avec des concentrations en cadmium dans les huîtres proches de la limite de consommation européenne (RNO 2006; 5 μg.g-1 ps, ECNo.466/2001). Ces travaux de recherche pluridisciplinaires ont pour objectif de caractériser le comportement des ETM en zone côtière et les mécanismes de contamination en ETM des huîtres, spécifiquement en Cd, dans la baie de Marennes Oléron. Pour cela, sept missions océanographiques en période contrastée ont permis de caractériser la spéciation des ETM à l’embouchure des estuaires de la Charente et de la Gironde ainsi qu’au Pertuis de Maumusson.Une étude spatio-temporelle complémentaire des sédiments de surface de la baie de Marennes Oléron a montré un enrichissement des sédiments de surface en Cd dans la zone sud baie,confirmant la connexion des eaux girondines et l’apport en Cd particulaire à la baie par le Pertuis de Maumusson. Cette zone sud a ainsi été choisie pour mener une transplantation d’huîtres pendant trois mois. L’hydrodynamique régionale, observée par imagerie satellite, a présenté unrôle important dans la distribution et la variation temporelle des concentrations en Cd dissous et particulaires minérales de la baie. La bioaccumulation en Cd des différents organes d’huîtres cultivées sur table a été plus importante que celle des huîtres cultivées directement sur le sol,suggérant le faible rôle de la diffusion de Cd par la remise en suspension des sédiments de surface et du microphytobenthos sur la bioaccumulation. De plus, le temps d’immersion étant relativement proche entre les deux conditions, nous suggérons que la voie trophique via le plankton pélagique participe à la contamination des huîtres en plus de la voie directe. Cette contribution de la voie trophique a été confirmée lors d’expérimentations en conditions contrôlées en laboratoire par le développement d’une méthode de traçage simultané des voies de contamination directe et trophique par ajouts d’isotopes stables de Cd, conduites pour des concentrations 10 fois supérieures à l’environnement et des concentrations réalistes observées en baie de Marennes Oléron (40 ng.l-1 et ~0.7 mg.kg-1). / The Marennes-Oléron Bay, hosting the largest oyster production in France, is influenced by thehistoric polymetallic pollution of the Gironde Estuary, with cadmium levels in oysters close tothe consumption limit level (5 μg.g-1 dw, EC No.466/2001). The aim of this pluridisciplinarywork was to characterize the behaviour of trace metals in the coastal zone and the mechanisms ofCd contamination in oysters in the Marennes Oléron Bay. Seven oceanographic cruises wereconducted during contrasting season to characterize trace metals behaviour and speciation in theGironde and Charente estuaries and the coastal zone. Then, a spatial and temporal study of tracemetals in the surface sediments of the Marennes-Oléron Bay showed punctual Cd-enrichedsediments in the southern part, reflecting the connexion with the Gironde waters and theparticulate Cd inputs via the Maumusson inlet. Thus, this area was chosen to study Cdbioaccumulation in oysters over a three months transplantation. The regional hydrodynamic,observed by satellite images, played an important role on Cd speciation and the temporalvariability of dissolved and particulate Cd concentrations. Cadmium bioaccumulation in organsof oysters reared on tables at 60 cm height was more important than in oysters reared near thesediment, suggesting the absence of Cd released during tidal suspension from sediment andmicrophytobenthos. Furthermore, as the immersion time was closed between the two rearingconditions, we suggested Cd bioaccumulation via the direct pathway and also via trophicpathway of contamination by pelagic plankton ingestion. This trophic pathway of Cdcontamination was validated during laboratory experiments using a simultaneous tracing of Cddirect and trophic pathways in oysters by stable isotope spikes at concencentrations 10-foldhigher than the Gironde Estuary and at realistic concentrations observed in the Marennes-OléronBay.

Sediments serve as the ultimate sink for many hydrophobic organic compounds and thus present a residual environmental risk many years after sources of contamination are eliminated. Monitored natural attenuation and ex situ treatment processes are often ineffective for treatment; as such in situ remediation technologies (i.e., capping) are under review. A conventional in situ remediation technology for refractory sediment contaminants is placement of a clean layer of material as a cap. A series of design models was developed to predict the performance of caps composed of the traditional material, sand. A passive sampling method using polydimethylsiloxane (PDMS) fibers for evaluating the performance of caps was developed and tested in the laboratory. The results of the laboratory analysis showed the ability to measure pore water concentration profiles in caps, the consistency of profiles with design model predictions, and correlation of PDMS-derived concentrations with contaminant uptake in test organisms. Potentially more effective caps composed of permeable adsorptive materials (to retard contaminant migration) and impermeable materials (to divert groundwater flow) were placed along with a conventional sand cap in the Anacostia River in Washington DC in 2004. Field tests of this site showed the ability to measure in situ pore water concentration profiles in caps using a field-deployable version of the PDMS passive sampling device and demonstrated the necessity of pore water-based approaches for analyzing caps. A model for assessing the uptake rates of HOCs within PDMS fibers was developed and shown to predict the kinetics of HOC sorption into fibers. The model is based on external-mass transport processes, which through a series of analyses were shown to be more significant than internal diffusion in PDMS fibers. Using the PDMS approach, field bioaccumulation tests at the Anacostia site as well as at San Diego Bay and Hunters Point Naval Shipyard showed stronger correlation of PDMS-based pore water concentrations than solid-phase concentrations with observations of bioaccumulation in the field. The overall conclusions suggest that pore water concentrations can often be a better indicator of risk than bulk solid concentrations. / text

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