The Mesozoic is punctuated by several rapid global warming events that are marked by the worldwide deposition of organic-rich marine sediments. These events, known as oceanic anoxic events (OAEs), are characterised by intervals where the worldwide carbon cycle suffers a disruption due to major palaeoceanographic and climatic shifts, leading to anoxic marine environments and the creation of black shales. For this study, the Oceanic Anoxic Event 1a (OAE 1a), which occurred during the Early Cretaceous Aptian age (~120 Ma) was analysed. It was likely triggered by the Greater Ontong Java underwater volcanic event and is associated with major changes in marine environments and ecosystems, including nekton and plankton turnover, and sea water composition changes. The impact of this event on terrestrial land-based ecosystems is, however, less well understood. Here I document well preserved and diverse spore-pollen assemblages spanning OAE 1a from southern Sweden by examining the Höllviken I core. Before the OAE, palynofloras are dominated by conifers, suggestive of a relatively mild and dry coastal environment. At the onset of the OAE a fern spike occurs, where there is a shift to early successional stage vegetation. Gymnosperm diversity and abundance sharply decrease, and the palynofloral assemblages become dominated by ferns, indicating a shift to warm and wet conditions. Gymnosperms gradually recover thereafter, but the formerly abundant conifer pollen Classopollis does not recover and remains rare. Dinoflagellate cysts and microforaminiferal test linings increase in abundance after OAE 1a, suggesting a higher degree of marine influence. These findings show that OAE 1a had a substantial impact on the composition and diversity of high latitude terrestrial vegetation and marine plankton communities. / <p>The work for this thesis was financially supported by the Erasmus Mundus Joint Master Degree PANGEA programme.</p>

The user's mobile communication device has an increasing sense of where the user is. This location information may be very fine grained or very coarse. Given some amount of location information it is possible to create location aware services. This thesis presents and evaluates a system for location aware web browsing. Indoors the user can click on a point on a map (to establish a virtual location using a previously installed user application), outdoors the location can be provided by GPS, or the location might be provided by some other location system (indoors or outdoors), then each HTTP GET request for a URL will be augmented with information about the user's location or their virtual location. Subsequently a web query is created. Then the location information encoded as longitude and latitude is appended to this web query. The web server uses this location information to generate dynamically location aware web pages. Finally a web browser shows the web pages. / Tillgång till information varsomhelst och vilken tid som helst är en viktig utkom av modern rörliga kommunikations systems. Alltmera har användarens terminal kännedom om användarens plats. Informationen om platsen kan vara lite eller omfattande. Tillgång till information om platsen gör det möjligt att skapa platsmedvetna tjänster. I den här master thesis presenterar och utvärderar jag ett system för plats medvetna web användning. Användaren klickar på en punkt på en karta (för att inrätta en virtuell lokalisering genom att använda tidigare installerat applikationer), sedan deras HTTP GET request för en URL utvidgas med information om användarens position eller deras virtuella (verkliga) lokalisering. En platsmedveten web query har skapats så att information om plats som latitude och longitude läggs till denna web query. Sedan en web server använder denna information för att generera dynamiska web sidor.

Daphnia is a widespread freshwater zooplankton species, which is both a classic and emerging new model for research in ecological physiology, ecotoxicology and evolutionary biology of adaptation to novel environments. Heat tolerance in Daphnia is known to depend both upon evolutionary history of a genotype and on individuals' acclimation to elevated temperature and to correlate with the level of haemoglobin expression. We demonstrate the existence of north-south gradient of heat tolerance in North American D. pulex, which is not associated with any parallel changes in haemoglobin expression. Geographically distinct clones differ in the way their haemoglobin expression changes due to acclimation to a sub-stressful (28°C) temperature, but these changes are not correlated with the latitude of clones' origin. Likewise, the effect of acclimation to sub-stressful temperature is independent from, and cannot be fully explained by, haemoglobin expression changes during acclimation. The degree of oxidative damage to haemoglobin, measured as the ratio of absorbance at 540:576 nm at the acclimation temperature, is a strong predictor of 28°C-acclimated Daphnia survival during an acute heat exposure. The comparison of haemoglobin expression in resistant and tolerant clones acclimated to different temperatures indicates that tolerant clones exhibit canalization of haemoglobin expression, possessing a high level of haemoglobin even at non-stressful temperatures. We discuss the evolutionary biology of adaptation and acclimation to elevated temperatures in an ecologically important component of freshwater ecosystems in the context of global climate change.

We used extensive measurements made by the Jicamarca Unattended Long-Term Investigations of the Ionosphere and Atmosphere (JULIA) and Incoherent Scatter Radar (ISR) systems at Jicamarca, Peru during geomagnetic quiet conditions to determine the climatologies of lunar tidal effects on equatorial vertical plasma drifts. We use, for the first time, the expectation maximization (EM) algorithm to derive the amplitudes and phases of the semimonthly and monthly lunar tidal perturbations. Our results indicate, as expected, lunar tidal effects can significantly modulate the equatorial plasma drifts. The local time and seasonal dependent phase progression has been studied in much more detail than previously and has shown to have significant variations from the average value. The semimonthly drift amplitudes are largest during December solstice and smallest during June solstice during the day, and almost season independent at night. The monthly lunar tidal amplitudes are season independent during the day, while nighttime monthly amplitudes are largest and smallest in December solstice and autumnal equinox, respectively. The monthly and semimonthly amplitudes decrease from early morning to afternoon and evening to morning with moderate to large increases near dusk and dawn. We also examined these perturbation drifts during periods of sudden stratospheric warmings (SSWs). Our results show, for the first time, the enhancements of the lunar semimonthly tidal effects associated with SSWs to occur at night, as well as during the day. Our results also indicate during SSWs, monthly tidal effects are not enhanced as strongly as the semimonthly effects.

Research over the years has established that the Gradient Drift Instability process causes small-scale irregularities, mostly along the edges of the high-latitude polar cap patches. Studying these irregularities will help in the development of a global Scale Ionospheric model, which is a central part of a global space weather forecast system. Much theoretical work has been done with varying degrees of complexity to study this instability in the high latitude patches. In this work we have used the Utah State University Time Dependent Ionospheric Model to model the high-latitude patches, calculate the growth rate of the instability, and perform a macro-scale study of the phenomenon. This is the first time that real ionospheric values have been used to calculate the growth rate and to provide two-dimensional maps identifying Gradient Drift Instability-caused irregularity regions in the polar cap. Our research shows that regions of intense instability occur along the edges of the tongue of ionization and its throat regions with strong rates along the borders of the cusp region.

High-latitude reefs have been postulated as refugia, centers for resilience or the first areas to undergo re-organization under climate change. The Southeast Florida Reef Tract (SEFRT) is a high-latitude reef system (>25 °N) running parallel to the highly urbanized coastline of southeast Florida. With a benthic community comprised of a mixture of coral reef associated assemblages, the SEFRT is towards the northern limit of stony coral cover due to temperature constraints. This study analyzed spatial variations in benthic cover, spatiotemporal changes in the benthic community and the impact of spatial and temporal fluctuations in temperature on benthic cover on the SEFRT, from 2007-2016. Photographic data from two long term monitoring projects was used to calculate the percent cover of taxonomic assemblages in the benthic community. In situ temperature data and modelled data from HYCOM were used in combination to assess the impact of temperature fluctuations and thermal stress events. Data was split on a latitudinal gradient into six defined ecosystem regions based on biogeographic boundaries and at major port channels. These accounted for any possible range expansion and spatiotemporal variations on the SEFRT. Statistical analysis via generalized linear models (GLM) identified significant changes in the major benthic taxa, stony coral, octocoral, sponges and macroalgae. Ecosystem regions showed strong clustering by their taxonomic composition and this was in part created by temperature variation. Stony coral cover significantly declined on the SEFRT and a concomitant significant increase in macroalgae cover may create a negative feedback loop which hinders recovery. Spatiotemporal variations in benthic cover were found between ecosystem regions and thermal stress events, both hot and cold, had immediate and latent impacts on benthic cover. This has resulted in biotic homogenization on the SEFRT with a retraction of outlier regions towards the mean. Anthropogenically influenced high-latitude reefs are significantly impacted by thermal stress. As oceans continue to warm, populations expand, coastlines continue to develop and pollutants persist, the benefits of potential thermal refugia are negated.

One of the central questions of ecology aims to understand the mechanisms that maintain patterns of species coexistence. Community assembly, the process of structuring communities, occurs in ecological time, is influenced by biotic interactions at local scales, and is thought to help maintain diversity patterns. Species invasions, however, as a result of globalization and intense marine trade, are common in coastal ecosystems, and have the potential to change the outcome of biotic interactions and community structure. Human-induced disturbance also disrupts community structure and coastal habitats are at greater risk due to encroachment of human populations near coasts. Changes in community structure are usually quantified as the number and distribution of species, however, the processes that shape communities act on the traits that allow and optimize species survival. Recently, ecological questions aiming to understand changes in community structure, invasion dynamics, and responses to disturbance are using measures that reflect species’ ecological functions (i.e., traits) and describe the trait composition of communities (i.e., functional structure and diversity).The objectives of my dissertation are to use functional diversity and structure to 1) determine trait responses from predation across latitude while considering interaction histories between native and introduced species with local predators, 2) use functional diversity patterns and changes in functional structure to infer the relative influence of predation and competition on community assembly through time and across latitude, and 3) assess trait responses to physical disturbance, also, through time and across latitude while considering the trait diversity of the system. To achieve these objectives, I used field experiments to grow coastal sessile marine invertebrate communities in treatments that test the influence of biotic interactions or disturbance. Experiments ran for three or twelve months at 12 sites in four regions of the Pacific Coast: Alaska, California, Mexico, and Panama. For my first objective, I found predation driven trait responses mainly occurred at lower latitudes where biotic interactions are expected to be stronger. Additionally, the native and introduced species of focal communities showed opposite trait responses to predation at lower latitudes with traits related to palatability and parental investment being primarily influenced. For my second objective, I found strong competition influenced late-stage assembly across the latitudinal gradient, while predation had a greater influence during early assembly in the tropics. Thus, the relative strength of biotic interactions changes with time and latitude and either predation or competition may serve as primary filters of community assembly. For my third objective, I found fast colonization and regeneration abilities help communities recover from intense disturbance, but only at lower latitudes where communities were most impacted by disturbance. In plant communities, functional traits have been studied quite extensively for several years and have set the stage for exploration in other ecosystems. In marine systems, the link between traits and ecological processes that influence community structure are mostly understudied, and my dissertation is contributing to close this knowledge gap about nearshore communities from across 47 degrees of latitude. / Biology

<p> "Jason's Creek" is a stream draining 2.2 km^2 of arctic limestone terrain. Its annual regime consists of a ten-month period in which it is frozen to its bed, a short spring flood which occurs shortly after tenperatures cross the freezing-point in late June, and a period of about two months during which discharge is relatively low and fluctuates diurnally in response to inputs of radiative and heat energy to the snowpack. In 1970, the spring flood occupied the first two weeks of July and effected the discharge of some nine-tenths of total annual runoff. Tne low flow period was punctuated by rainstorms which generated sharply-defined floods: basin response was rapid and efficient, for storm runoff is facilitated over the unvegetated ground and through the shallow active layer above the permafrost table. Covariance and spectral analyses suggest a basin lag time of five hours, both for low discharges of snowmelt water and flood discharge of rainwater. It appears, from the spectra of the time series, that radiation is a better index of snowmelt discharge than is temperature.</p> <p> Most of the annual removal of sediment from the basin takes place during the spring flood, when the stream is turbid and movement of channel bed material is vigorous, In the longer period after the flood the main component of stream load is the solute load. The concentration of dissolved material varies inversely while suspended sediment concentration varies directly with discharge. Solute concentrations are lower than those commonly found in limestone streams at lower latitudes, suggesting that in "Jason's Creek" the increased solubility of CO2 at low temperatures is more than counteracted by a decrease in the rate of solution of CaCO3. There are also indications that the concentration of CO2 in snowmelt water 2 may be smaller, in absolute terms, than in rainwater.</p> <p> The role of water is crucial in many processes acting on slopes and delivering detritus to stream channels; rills, for example, remove ions in solution and fine particles in suspension, notably from the base of talus slopes, and lubrication of the active layer after rainstorms generates bowl-slide and mudflow activity.</p> / Thesis / Master of Science (MSc)

L’objectif principal de ce mémoire est d’approfondir les connaissances à propos de l’impact des stresseurs organisationnels sur la concentration du cortisol salivaire. Plus précisément, nous étudierons la contribution des modèles demande-contrôle de Karasek (1979) et demande-contrôle-soutien de Karasek et Theorell (1990) à la variation du cortisol salivaire chez les individus. Les associations entre les composantes principales de chacun des modèles (demandes psychologiques, latitude décisionnelle et soutien social), mais également les effets d’interaction inclus dans ces modèles, c’est-à-dire de l’effet modérateur de la latitude décisionnelle et du soutien social, seront étudiés. L’axe HPS a été associé aux symptômes de la santé mentale (Abelson et al., 2007; Havermans et al., 2011; Vreeburg et al., 2009b, 2010, 2013; Staufenbiel, 2013) ainsi qu’aux stresseurs en milieu de travail (Chida et Steptoe, 2009). À l’heure actuelle, le cortisol salivaire serait un indicateur de l’axe hypothalamo-pituito-surrénalien (HPS) le plus prometteur pour mesurer la réponse physiologique face à un événement stressant ou à un stress chronique (Maïna et al., 2009). Les données proviennent de l’étude SALVEO, menée par l’Équipe de recherche sur le travail et la santé mentale de l’Université de Montréal. Les résultats des analyses multiniveaux ne soutiennent pas l’implication du modèle demande-contrôle-soutien sur la concentration de cortisol. En effet, elles ne permettent pas de conclure que les effets, autant principaux que d’interaction, du modèle demande-contrôle-soutien expliquent la variation dans les concentrations de cortisol. La consommation de tabac est significativement reliée à la concentration de cortisol salivaire et doit être prise en considération dans les études futures. Par conséquent, ces résultats suggèrent que d’autres recherches sont nécessaires pour comprendre comment les stresseurs du travail s’incorporent à l’individu au niveau physiologique. Des connaissances approfondies de ces associations permettraient de mieux comprendre les associations entre le stress à long terme et les effets sur la santé, c’est-à-dire, comment les tensions au travail affectent la santé mentale à long terme (Karhula et al., 2015). / The main objective of this master thesis is to increase the knowledge about the impact of organisational factors on salivary cortisol concentrations. Especially, the models demand-control (Karasek, 1979) and demand-control-support (Karasek and Theorell, 1990) will be studied in relationship to the salivary cortisol. The objectives of this study are to investigate the associations between the main components of each model (psychological demands, decision latitude and social support), but also patterns of interaction effects, i.e. the effect moderator of decision latitude and social support. It has been shown that the HPA axis would be linked to symptoms of mental health (Abelson et al., 2007; Havermans et al. 2011; Vreeburg et al. 2009b, 2010, 2013; Staufenbiel, 2013) as well as stressors in the workplace (Chida and Steptoe, 2009). Currently, salivary cortisol, an indicator of the hypothalamic-pituitary-adrenal axis (HPA) or the axis of stress management, would be the most promising for measuring the physiological response to a stressful event or chronic stress (Maïna et al. 2009). The data results come from the SALVEO surveys led by the research team on work and mental health of University of Montreal (ERTSM). Results of multilevel analyses do not support the involvement of the demand - control - support model to changes in cortisol concentration. Indeed, they do not suggest that the main effects as much as the interaction effects of the demand-control-support model, explain the variation in cortisol levels. Tobacco consumption is significantly related to salivary cortisol concentration and must be taken into account in previous studies. Therefore, these results suggest that further research is needed to understand how the occupational stressors are incorporated into the individual at the physiological level. Depth knowledge of these associations would help to understand the associations between long-term stress and health effects or how job strain affects long-term mental health (Karhula et al. 2015).

Structurée en trois principaux chapitres, cette étude présente une approche pluridisciplinaire en combinant desanalyses spatiales et temporelles de la variabilité interannuelle des saisons de pluies d’une base de données agroclimatique,des essais phénologiques mensuelles d’une sélection de variétés photopériodiques de mil et de sorgholocales et améliorées, et l’utilisation conjointe d’un modelé de culture calibre pour les effets de la latitude et d’unSystème d’Information Géographique (SIG). Elle permet de tirer des conclusions originales et d’identifier lesenvironnements cibles prometteurs pour la vulgarisation des variétés de mil et de sorgho photopériodiques enAfrique de l’Ouest. Elle met en évidence l’existence de relations significatives entre les réponses phénologiques,le degré de sensibilité à la photopériode des variétés et les facteurs environnementaux, dont les principales sont :‒ La variabilité interannuelle des pluies en Afrique de l’Ouest durant les cinquante dernières années (1950-2000) est marquée par une diminution globale de la pluviométrie annuelle caractérisée par une variabilitéaccrue des dates de début de saison des pluies dans les latitudes basses que dans les latitudes élevées etune variabilité interannuelles des dates de fin de saison plus notable sur les latitudes du Nord plus quedans les basses latitudes au sud.‒ La distribution spatiale des variétés de mil et de sorgho photopériodiques est étroitement liée à larépartition spatiale et temporelle de la variabilité des dates de débuts et de fin de la saison de pluies. Lesvariétés photopériodiques se localisent essentiellement dans les basses latitudes ou la variabilité des datesde début de saison est plus élevée que celle des dates de fin de saison plus stable.‒ La réponse phénologique des variétés de mil et de sorgho photopériodiques est strictement dépendantede la date de semis et de la latitude. Les effets de la latitude sur la phénologie et la réactionphotopériodique des variétés est proportionnelle à la distance entre la zone de culture d’une variété et salatitude d’origine.‒ Le modèle de développement des céréales photopériodiques « Impatience » calibré et corrigé à cet effet(effet de la latitude) prévois et défini avec plus de précision les zones d’adaptation variétale optimale pourles variétés de mil et de sorgho photopériodiques en Afrique de l’Ouest.‒ L’adéquation entre la durée du cycle phénologique calibrée par le modèle de culture corrigé de l’effet dela latitude et celle observée dans les systèmes agraires à base de mil et de sorgho photopériodiques dansles agro-systèmes villageois au Mali valide le modèle les cartes d’adaptation variétale optimale. / Structured in three main chapters; this study addresses multidisciplinary approach combining spatial and temporalanalysis of interannual variability of rainfall, multi-locations trials of a large and representative sample of photoperiodicvarieties of sorghum and millet combined with a photoperiod response crop model and Geographic Information System(GIS). It allowed identifying specific target environment to promote the vulgarization of photoperiodic varieties ofsorghum and millet in West Africa. This study depicted significant relationships between phenology, PP sensitivityresponses and environmental factors, where the mains components are listed below:‒ The interannual rainfall variability in West Africa over the past fifty years (1950-2000) was marked by ageneral decrease in annual rainfall characterized by high variability in the onset of growing period at lowerlatitudes and an increase in the interannual variability of the end of growing period in the northern latitudeswith least significant variability through climatic periods.‒ The spatial distribution of PP sensitivity varieties of millet and sorghum is closely related to the spatial andtemporal distribution of the interannual variability of the onset and end dates of growing period. Photoperiodsensitive varieties are located mainly at lower latitudes where the interannual variability in the onset of thegrowing period is much higher than the end of the growing period.‒ Phonological response and expression of photoperiod sensitivity are strictly dependent on sowing date andlatitude. Effects of latitude on the expression of photoperiod sensitivity and phenology are proportional tolatitude.‒ The "impatience" sub-crop model calibrated and corrected for latitudinal effect predicts and identifies moreaccurately optimal varietal adaptation areas for sorghum and millet varieties in West Africa.‒ The adequacy between calibrated duration of the phonological cycle by the crop model adjusted for latitudinaleffect and that observed in farming systems in agro-systems in Mali, allowed to validate the predicted optimalvarietal adaptation maps by defined the model.