L'ozone (O3) possède une anomalie isotopique en oxygène qui est unique et caractéristique, offrant ainsi un précieux traceur des processus oxydatifs à l'œuvre dans l'atmosphère moderne mais aussi ceux ayant eu lieu dans le passé. Cette signature isotopique, dénotée Δ17O, se propage au sein du cycle atmosphérique de l'azote réactif (NOx = NO + NO2) et est préservée lors du dépôt du nitrate (NO3-) présent dans l'aérosol, par exemple. L'anomalie isotopique en oxygène portée par le nitrate, Δ17O(NO3-), représente ainsi un traceur de l'importance relative de l'ozone ainsi que celle d'autres oxydants dans le cycle des NOx. Ces dernières années, de nombreux travaux de recherche ont été dédiés à l'interprétation des mesures de Δ17O(NO3-). Pourtant, les processus atmosphériques responsables du transfert de l'anomalie isotopique de l'ozone vers le nitrate ainsi que leur influence globale sur la composition isotopique du nitrate à différentes échelles spatiales et temporelles sont encore mal compris. De plus, la magnitude absolue ainsi que la variabilité spatio-temporelle de Δ17O(O3) sont peu contraintes, car il est difficile d'extraire de l'ozone de l'air ambiant. Cet obstacle technique contrecarre l'interprétation des mesures de Δ17O depuis plus d'une décennie. Les questions scientifiques posées au cours de ce travail de thèse ont été choisies dans le but de combler ces lacunes. Le principal outil d'analyse utilisé dans ce travail est la « méthode bactérienne » associée à la spectrométrie de masse en flux continu (CF-IRMS), une combinaison de techniques qui permet l'analyse de la composition isotopique totale du nitrate (c'est-à-dire, la mesure de δ15N, δ18O et Δ17O). Cette méthode a été employée pour l'analyse isotopique d'échantillons de nitrate obtenus pour deux cas d'études : (i) une étude des variations spatiales de la composition isotopique du nitrate atmosphérique sur la côte californienne à l'échelle journalière; et (ii) une étude du transfert du nitrate et de sa composition isotopique à l'interface entre l'air et la neige à l'échelle saisonnière sur le plateau Antarctique. En outre, cette méthode a été adaptée à la caractérisation isotopique de l'ozone via la conversion chimique de ses atomes d'oxygène terminaux en nitrate. Au cours de cette thèse, un important jeu de données rassemblant de nombreuses mesures troposphériques de Δ17O(O3) a été obtenu, incluant une année entière de mesures à Grenoble, France (45 °N) ainsi qu'un transect latitudinal de collecte dans la couche limite au-dessus de l'océan Atlantique, entre 50 °S to 50 °N. Ces observations ont permis de doubler le nombre de mesures troposphériques de Δ17O(O3) existantes avant cette thèse et d'accroître de manière conséquente notre représentation globale de cette variable isotopique essentielle. Enfin, les deux cas étudiés et présentés dans ce document révèlent des aspects nouveaux et inattendus de la dynamique isotopique du nitrate atmosphérique, avec d'importantes conséquences potentielles pour la modélisation de la qualité de l'air et l'interprétation de l'information isotopique contenue dans les carottes de glace prélevées aux pôles. / The unique and distinctive 17O-excess (Δ17O) of ozone (O3) serves as a valuable tracer for oxidative processes in both modern and ancient atmospheres. This isotopic signature is propagated throughout the atmospheric reactive nitrogen (NOx = NO + NO2) cycle and preserved in nitrate (NO3-) aerosols and mineral deposits, providing a conservative tracer for the relative importance of ozone and other key oxidants involved in NOx cycling. However, despite the intense research effort dedicated to the interpretation of Δ17O(NO3-) measurements, the atmospheric processes responsible for the transfer of Δ17O to nitrate and their overall influence on nitrate isotopic composition on different spatial and temporal scales are not well understood. Furthermore, due to the inherent complexity of extracting ozone from ambient air, the absolute magnitude and spatiotemporal variability of Δ17O(O3) remains poorly constrained, a problem that has confounded the interpretation of Δ17O measurements for over a decade. The research questions that have been pursued in this thesis were formulated to address these knowledge gaps. The primary analytical tool used was the bacterial denitrifier method followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS), which allows for the comprehensive isotopic analysis of nitrate (i.e., δ15N, δ18O, Δ17O). This method was applied to the isotopic analysis of nitrate samples in two case studies: (i) an investigation of the diurnal and spatial features of atmospheric nitrate isotopic composition in coastal California; and (ii) a study of the seasonality and air-snow transfer of nitrate stable isotopes on the Antarctic plateau. Furthermore, the method was adapted to the isotopic characterization of ozone via chemical conversion of its terminal oxygen atoms to nitrate. During the course of this thesis, a large dataset of tropospheric Δ17O(O3) measurements has been obtained, including a full annual record from Grenoble, France (45 °N) and a ship-based latitudinal profile from 50 °S to 50 °N in the Atlantic marine boundary layer (MBL). This observational dataset represents a two-fold increase in the number of existing tropospheric Δ17O(O3) observations and a dramatic expansion in the global representation of this key isotopic variable. Additionally, the two case studies presented reveal novel and often unexpected aspects of the isotope dynamics of atmospheric nitrate, with potentially important implications for air quality modeling and the interpretation of isotopic information preserved in the polar ice core record.

Chapter 1: Antarctic fishes are extremely cold adapted. Despite their inability to upregulate heat shock proteins, recent studies have demonstrated a capacity for heat response in these animals. A cDNA microarray study looked at the Notothenioid fish Trematomus bernacchii and revealed heat sensitivities for hundreds of genes, two of which code for members of the CCAAT/Enhancer-binding protein (C/EBP) family of transcription factors. These molecular switches are best known for their roles in apoptosis, inflammation and cell cycle arrest. This dissertation further elucidates the role of C/EBP-delta in the Antarctic fishes T. bernacchii and Pagothenia borchgrevinki. Chapter 2: C/EBP-delta is constitutively expressed in unstressed, field-acclimated (ca. -1.86°C) animals in a highly tissue-specific manner. White muscle tissue contains the highest C/EBP-delta concentration, which is further increased in response to sublethal heat stress at 2.0 or 4.0°C. This response is mostly acute and transitory, but a lesser upregulation was observed in fishes held for one month at 4.0°C. Chapter 3: The heat-induced nuclear translocation of C/EBP-delta--as determined by immunohistochemistry--appears to be time, tissue and species specific with spleen, heart and retinae being particularly responsive in certain situations. Chapter 4: Protein concentrations of proliferating cell nuclear antigen are tissue specific and variably heat responsive. Surprisingly, levels appear to be positively correlated with C/EBP-delta. Chapter 5: Flow cytometry revealed increasingly high temperatures reduce the proportion of G1 cells while increasing the abundance of apoptotic cells. Chapter 6: These findings are discussed in the context of global climate change and the cellular stress response.

This study establishes an initial understanding of the state of cruise tourism in the Eastern Canadian Arctic. Two specific objectives were fulfilled; a) to develop an understanding of the goals and operational procedures of current cruise ship operators, and b) to provide insight into the policies that may be necessary for Parks Canada and the Canadian Wildlife Service to enhance management in parks and protected areas. <br /><br /> Cruise tourism in the Eastern Canadian Arctic is a relatively new industry. At present, there is a lack of inclusive government guidelines for the Canadian cruise tourism industry. The steady increase of cruise tourism traffic in the region since 1984 suggests the potential for environmental and social impacts to this fragile polar region. There is a need for the creation of guidelines to direct this tourism activity. <br /><br /> A literature review identified the current state of the cruise line industry in the Eastern Canadian Arctic, Antarctic and Alaskan waters. The policy requirements pertaining to cruise tourism in parks and protected areas were identified including the current management strategies for tourism employed in Northern Canadian parks and protected areas. <br /><br /> Content analysis of current cruise tourism literature themes, which were used to create and conduct interviews that explored these themes. From these findings, data was used to create a policy formation framework that will assist in the planning and management of cruise tourism in the Eastern Canadian Arctic. <br /><br /> The results indicated that cruise tourism in the Eastern Canadian Arctic is percevied as a safe and economically viable industry. The research found a high degree of coherence between the literature and the opinion of the stakeholders in regards to key issues that need to be addressed. Such issues include the need for greater academic research on this topic; the need for policies and guidelines to aid in the management of parks and protected areas in polar regions; a need for unity and cohesion in the Arctic Cruise Tourism Industry and finally, greater government awareness and assistance given to the cruise tourism industry in the Eastern Canadian Arctic. There was also a high degree of enthusiasm from the stakeholders for inter-group and interagency cooperation. This enthusiasm bodes well for the future of cruise tourism policy creation in the Eastern Canadian Arctic. <br /><br /> This thesis proposes a structure for the way forward.

This study establishes an initial understanding of the state of cruise tourism in the Eastern Canadian Arctic. Two specific objectives were fulfilled; a) to develop an understanding of the goals and operational procedures of current cruise ship operators, and b) to provide insight into the policies that may be necessary for Parks Canada and the Canadian Wildlife Service to enhance management in parks and protected areas. <br /><br /> Cruise tourism in the Eastern Canadian Arctic is a relatively new industry. At present, there is a lack of inclusive government guidelines for the Canadian cruise tourism industry. The steady increase of cruise tourism traffic in the region since 1984 suggests the potential for environmental and social impacts to this fragile polar region. There is a need for the creation of guidelines to direct this tourism activity. <br /><br /> A literature review identified the current state of the cruise line industry in the Eastern Canadian Arctic, Antarctic and Alaskan waters. The policy requirements pertaining to cruise tourism in parks and protected areas were identified including the current management strategies for tourism employed in Northern Canadian parks and protected areas. <br /><br /> Content analysis of current cruise tourism literature themes, which were used to create and conduct interviews that explored these themes. From these findings, data was used to create a policy formation framework that will assist in the planning and management of cruise tourism in the Eastern Canadian Arctic. <br /><br /> The results indicated that cruise tourism in the Eastern Canadian Arctic is percevied as a safe and economically viable industry. The research found a high degree of coherence between the literature and the opinion of the stakeholders in regards to key issues that need to be addressed. Such issues include the need for greater academic research on this topic; the need for policies and guidelines to aid in the management of parks and protected areas in polar regions; a need for unity and cohesion in the Arctic Cruise Tourism Industry and finally, greater government awareness and assistance given to the cruise tourism industry in the Eastern Canadian Arctic. There was also a high degree of enthusiasm from the stakeholders for inter-group and interagency cooperation. This enthusiasm bodes well for the future of cruise tourism policy creation in the Eastern Canadian Arctic. <br /><br /> This thesis proposes a structure for the way forward.

L’étude des mécanismes endocriniens est particulièrement intéressante du fait du rôle majeur des hormones dans la régulation des interactions entre la physiologie d’un organisme, son comportement, et les modifications de son environnement. Cette thèse s’est intéressée aux relations entre le statut hormonal, les performances de reproduction et le succès reproducteur d’un oiseau marin longévif, le manchot Adélie Pygoscelis adeliae, dans un contexte environnemental soumis à des changements. Le statut endocrinien de manchots mâles a été manipulé en utilisant des implants dégradables sous-cutanés diffusant l’hormone d’intérêt ou un inhibiteur de sa sécrétion. Les effets d’une modification des niveaux d’hormones sur l’investissement parental pendant l’incubation ont été mesurés à l’aide d’observations directes et d’oeufsfactices enregistrant les paramètres d’incubation. Les niveaux de corticostérone – hormone dite de stress, de prolactine – hormone des soins parentaux, et de testostérone – hormone liée aux comportements sexuels et à l’agressivité, ont été manipulés. Les effets d’une augmentation des niveaux de corticostérone sur les performances et le succès reproducteur pendant la période de l’élevage des poussins ont également été mesurés. Enfin, les conséquences d’une légère élévation des niveaux de corticostérone pendant l’ensemble de la saison de reproduction en termes de comportement et de succès reproducteur ont été examinées. Une augmentation des niveaux de corticostérone a globalement diminué les performances et le succès de reproduction. D’autre part, une modification des niveaux de prolactine ou de testostérone a affecté la durée etles paramètres d’incubation, suggérant une implication de ces deux hormones dans le contrôle de la phénologie de la reproduction. Les résultats présentés dans cette thèse mettent l’accent sur le fait que la relation entre statut endocrinien et performances de reproduction est dose, état et contexte dépendante. Nos résultats illustrent le rôle majeur des hormones étudiées dans la régulation de l’effort reproducteur, et soulignent également l’importance de considérer les interactions entre les organismes et leur environnement. / Studying endocrine mechanisms is of particular interest because of the major role played by hormones in mediating interactions between an animal’s physiology, its behaviour, and both predictable and unpredictable regimes of environmental variation. During this PhD, I have investigated the relationships between endocrine status, reproductive performance, and reproductive output in a long-lived polar seabird, the Adélie penguin Pygoscelis adeliae, while integrating environmental parameters for some of the studies. The endocrine status of male penguins was experimentally modified using subcutaneous self-degradable pellets, which released either the hormone or an inhibitor of its secretion. The effects of changes in the levels of several hormones on the parental investment during incubation were assessed, using direct observations and dummy eggs to record incubation parameters. The levels of corticosterone – the so-called stress hormone, prolactin – the parental care hormone, and testosterone – the sexual behaviour and aggressiveness hormone, were manipulated. The effects of increased corticosterone levels on reproductive performance and output were also evaluated during the chick-rearing period. Finally, the behavioural consequences of a moderate elevation of corticosterone levels during the whole breeding cycle were assessed. On the whole, an increase in corticosterone levels decreased reproductive performances and output. Changes in prolactin or testosterone levels affected incubation duration and egg temperature, suggesting a role for these hormones in the control of the timing of breeding. The results prevented in this PhD highlight the fact that the relationship between endocrine status and reproductive performance is dose-, state-, and context-dependant. Our results illustrate the major role of the hormones considered in our studies in the regulation of reproductive effort. They also underline the importance of considering the interactions of organisms with their environment in studies of animal behaviour and ecophysiology.

L’espace souterrain, qui s’étend depuis la surface des terres émergées et des fonds marins jusqu’au centre de la Terre, est délaissé par le droit international. Aucune règle de droit international positif ne vient réglementer l’utilisation que les Etats font de leur espace souterrain territorial, cette utilisation et le régime de la propriété souterraine faisant partie de leur domaine réservé. Si les normes internationales régissent l’utilisation de l’espace souterrain extra-territorial, celui des grands fonds marins et celui de l’Antarctique, elles n’appréhendent l’espace souterrain qu’en termes d’utilisation et de mise en valeur des ressources minérales. De ce régime juridique d’exploration et d’exploitation des ressources minérales dépend d’ailleurs le statut juridique de l’espace souterrain qui va de la pleine souveraineté de l’Etat côtier à l’exclusion de toute appropriation nationale ou individuelle. Devant la multiplication des utilisations souterraines et face aux dommages environnementaux et aux violations des droits de l’homme liés à certaines de ces utilisations, le droit international doit réinvestir l’espace souterrain et notamment le contenu et l’étendue des droits qui le concernent tant dans l’ordre interne qu’international afin d’en réglementer la mise en valeur et d’en assurer la protection. / Until today, there has been little interest of international Law concerning the earth’s subsurface, as the space that extends from the surface of the soil or of the seabed to the center of the earth. On the one hand, there is no rule of international law that regulates the use Sovereign States have of their territorial subsurface. It is currently understood that subsburface activities and property law that regulates them, are within domestic jurisdiction only and do not come under international law scrutinity as they waive the exercice of an absolute independance of States. On the other hand, the existing rules of international law that regulates extraterritorial subsurface, notably the seabed and ocean floor and subsoil thereof beyond national jurisdiction and the Antarctic, consider the earth’s subsurface mostly in terms of use and exploitation of mineral resources. Faced with the evergrowing uses of the subsurface that are solely used for extraction or for injection and storing, and regarding the impacts of some underground activities on the environment and on human rights, International Law must play a role by regulating the content and extent of rights that are exercised over the earth’s subsurface inside and outside territorial jurisdiction for development and protection purposes.