The ability to grip on petal surfaces is of crucial importance for the interactions between bees and flowers. In this thesis, I explore the biomechanics of attachment and morphological diversity of bee attachment devices, linking this to the behavioural ecology of bee interactions with flowers. Attachment devices come in two main kinds: claws or spines, and adhesive pads. Claw functioning is poorly described, particularly in terms of how their performance depends on body size, claw geometry, and surface roughness. Claw attachment performance was investigated using several insect species, each covering a large range of body masses. Weight-specific attachment forces decreased with body size, with claw sharpness seemingly playing a role. In bees there is considerable interspecific variation in tarsal claw morphology. This variation, and arolia presence/absence, was categorised for the large bee family Apidae. Cleft/bifid claws were shown to be present in the majority of the Apidae, often with differences between sexes and clades. Using Bombus terrestris, there was no evidence that cleft claws are important for pollen collection; however, I found that the inner tooth of cleft claws can act as a backup if the main tooth breaks. Although this may be one function of cleft claws, there are clearly other unresolved functions well worth further exploration. Investigations were undertaken to explore how petal surface roughness affects bee foraging behaviour. Lab-based foraging trials on B. terrestris visiting artificial flowers varying in slope, surface texture and sugar reward revealed a trade-off between the biomechanical difficulty of visiting and handling the ‘flowers’ and the quality of the reward offered. Flowers that were difficult to grip were often avoided even if they offered a higher reward. To further investigate reward preferences of bees, the effect of sucrose concentration on honey stomach offloading times was also explored. Although the majority of petals do have a rough surface, some have slippery petals. In the field, bumblebees avoided landing on slippery hollyhock petals in favour of the easy-to-grip staminal column. In contrast, honey bees, which are smaller and have larger adhesive pads, landed on both the staminal column and the petals. Slippery petals may be an adaptation to increase contact with plant reproductive structures. Grip is also important to allow the honey bee parasite Varroa destructor to climb on to their host. Attachment forces experiments found that V. destructor could support > 300 times their body mass on honey bees, giving them strong attachment even when bees attempt to remove them through grooming. A grooming-based device for treating V. destructor was tested in an apiary trial. The device was ineffective, providing valuable information for beekeepers considering using this product. In summary, this thesis improves our understanding of the biomechanics of attachment as well as identifying several important aspects of grip in bee-plant interactions.

Made available in DSpace on 2014-12-17T15:36:35Z (GMT). No. of bitstreams: 1 KellyCAP.pdf: 2804234 bytes, checksum: e14a879efe151d80522174c9403f357e (MD5) Previous issue date: 2009-02-13 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / This study investigated factors that influence the group size during the behavior foraging of estuarine dolphin Sotalia guianensis in the coast south of the state Rio Grande do Norte (RN), it also characterized the diet of estuarine dolphins and elaborated an otoliths catalog for aid in the identification of the preys found in the stomach contents. In relation to the group size during behaviour foraging, inside of the Curral Bay, larger frequency of solitary hunt was observed. Factors as tide variation, group composition and seasons didn't present correlation with the number of animals observed during a feeding episode. Capture success for participant was shown significantly larger when the animals hunted alone, what possibly explains the largest frequency of solitary hunt inside of the Curral Bay. About diet, were identified 18 bone fishes species, with predominance of species the families Haemulidae and Sciaenidae and five cephalopods species, including two new species in the diet of Sotalia guianensis in Brazil. Our results indicated that estuarine dolphin in the coast oriental from Rio Grande do Norte (RN) feeds predominantly of fish that form shoal, of habitat estuarino and producing of sounds. The analysis of the images, otoliths of 43 species of coastal fish of the coast of the state of Rio Grande do Norte (RN), aided by the offered descriptions, demonstrated to be an effective methodology for the knowledge of those structures, as well as it represented a form of reducing the subjectivity in the identification of the bone fishes found in stomach content / Esse trabalho investigou os fatores que influenciam o tamanho de grupo durante o comportamento alimentar do boto cinza Sotalia guianensis no litoral sul do estado do Rio Grande do Norte (RN), tamb?m caracterizou a dieta dessa esp?cie na regi?o e elaborou um cat?logo de ot?litos para auxiliar ? identifica??o das presas encontradas nos conte?dos estomacais dos animais analisados. Em rela??o ao tamanho de grupo durante o forrageio, dentro da enseada do curral, foi observado maior freq??ncia de ca?a solit?ria. Fatores como varia??o de mar?, composi??o de grupo e esta??es do ano n?o apresentaram correla??o com o n?mero de animais observados durante um epis?dio de alimenta??o. Contudo, o sucesso de captura por participante mostrou-se significativamente maior quando os animais ca?avam sozinhos, o que possivelmente explica a maior freq??ncia de ca?a solit?ria dentro dessa enseada. Sobre a caracteriza??o da dieta, foram identificadas 18 esp?cies de tele?steos, com predomin?ncia de esp?cies pertencentes ?s fam?lias Haemulidae e Sciaenidae e cinco esp?cies de cefal?podes, incluindo duas esp?cies ainda n?o registradas na dieta de Sotalia guianensis no Brasil. De acordo com as informa??es sobre a dieta, o boto cinza no litoral oriental do Rio Grande do Norte (RN) alimenta-se predominantemente de peixes que formam cardume, de habitat estuarino e produtores de sons. A an?lise das imagens dos ot?litos de 43 esp?cies de peixes costeiros do litoral do estado do Rio Grande do Norte (RN) demonstrou ser uma metodologia eficaz, bem como representou uma forma de diminuir a subjetividade na identifica??o dos tele?steos encontrado em conte?do estomacal

Made available in DSpace on 2014-12-17T15:36:35Z (GMT). No. of bitstreams: 1 LeonardoBR_TESE_Cap_II_III.pdf: 677404 bytes, checksum: 247b1251f8d1d16cb41bf4f8ec2f3c18 (MD5) Previous issue date: 2010-03-19 / Universidade Federal do Rio Grande do Norte / This study evaluated the spatial, time and alimentary niches of Tropidurus hispidus and Tropidurus semitaeniatus in sympatry in a caatinga of Rio Grande do Norte, Brazil, as well as their foraging and termoregulatory behaviors, the activity body temperature and their reproductive and fat body cycles. Monthly excursions, from October 2006 to May 2008, were conducted at the Ecological Station of the Serid? (ESEC Serid?), Serra Negra do Norte municipality, using specific methodology for investigation of the aforementioned objectives. The two species presented similarities in space niche use, mainly in rocky habitat, however they differed in vertical microhabitat use with T. hispidus using a larger vertical microhabitat range. In the dry season the time of activity of both species was bimodal. In the wet season T. semitaeniatus showed a unimodal activity period, while T. hispidus maintained an bimodal activity period. In terms of importance in the diet, to both species, Hymenoptera/Formicidae and Isoptera predominated during the dry season. In the wet season, although Hymenoptera/Formicidae had larger importance among the prey items, lizards opportunistically predated on Lepidoptera larvae, Coleoptera larvae/adults and Orthoptera nymphs/adults. The foraging intensity revealed differences between the species, mainly in the wet season, when T. semitaeniatus was more active than T. hispidus. The mean activity body temperature of T. semitaeniatus was significantly higher than that of T. hispidus. The thermoregulatory behavior showed that during the dry season T. hispidus and T. semitaeniatus spent more time in shade or under filtered sun. In the wet season, T. hispidus did not show differences in the amount of time spent among the light exposure locations, however T. semitaeniatus spent most of their time exposed to direct sun or filtered sun. The reproductive cicle of T. hispidus and T. semitaeniatus occurred from the middle of the dry season to the beginning of the wet season. In both species, female reproductive activity was influenced by precipitation, whereas males exhibited spermatozoa in their testes throughout the year, and their reproductive activity was not related with any of the climatic variables analysed. In the two species, the fat storage varied inversely with reproductive activity, and there was no difference in fat body mass between females and males. We concluded that the segregation between T. hispidus and T. semitaeniatus in this caatinga area occurs in vertical space use, in the largest vagility of T. hispidus in microhabitat use and larger range size of their alimentary xviii items. Additionally, significant seasonal differences in relation to the activity period, body temperature, and foraging and termoregulatory behaviors between these two Tropidurus species facilitate their coexistence. / Este estudo avaliou o uso dos recursos espacial, temporal e alimentar por Tropidurus hispidus e Tropidurus semitaeniatus em simpatria em uma caatinga do Rio Grande do Norte, Brasil, bem como seus comportamentos de forrageamento e termorregulat?rio, suas temperaturas corp?reas em atividade e seus ciclos reprodutivos e de gordura corp?rea. Excurs?es mensais, de outubro de 2006 a maio de 2008, foram realizadas ? Esta??o Ecol?gica do Serid? (ESEC Serid?), munic?pio de Serra Negra do Norte, com utiliza??o de metodologia espec?fica para a investiga??o dos objetivos acima mencionados. As duas esp?cies apresentaram similaridades no uso do nicho espacial, especialmente no h?bitat rochoso; contudo, elas diferiram no uso vertical do micro-h?bitat com T. hispidus usando uma faixa vertical maior do micro-h?bitat. Na esta??o seca o per?odo de atividade de ambas as esp?cies foi bimodal. Na esta??o chuvosa, a atividade de T. semitaeniatus mostrou um per?odo unimodal, enquanto T. hispidus manteve uma atividade bimodal. Em termos de import?ncia na dieta, para ambas as esp?cies, os Hymenoptera/Formicidae e Isoptera predominaram na esta??o seca. Na esta??o chuvosa ainda que os Hymenoptera/Formicidae continuaram a ter maior import?ncia entre os itens alimentares, os lagartos predaram oportunisticamente larvas de Lepidoptera, larvas/adultos de Coleoptera e ninfas/adultos de Orthoptera. A medida de intensidade de forrageamento revelou diferen?as entre as esp?cies, especialmente na esta??o chuvosa, quando T. semitaeniatus foi mais ativo do que T. hispidus. A temperatura corp?rea m?dia em atividade de T. semitaeniatus foi significativamente superior a de T. hispidus. O comportamento termorregulat?rio mostrou que, durante a esta??o seca, T. hispidus e T. semitaeniatus gastaram mais tempo expostos ? sombra ou sob sol filtrado. Na esta??o chuvosa, T. hispidus n?o mostrou diferen?as no tempo gasto entre os locais de exposi??o ? luz, contudo T. semitaeniatus esteve a maior parte de seu tempo exposto ao sol ou sob sol filtrado. A reprodu??o de T. hispidus e T. semitaeniatus ocorreu entre a metade da esta??o seca e o in?cio da esta??o chuvosa. Em ambas as esp?cies, a atividade reprodutiva das f?meas foi influenciada pela precipita??o, enquanto os machos apresentaram espermatoz?ides nos test?culos ao longo de todo o ano, e sua atividade reprodutiva n?o foi relacionada com nenhuma das vari?veis clim?ticas analisadas. O estoque de gordura corp?rea variou inversamente com a atividade reprodutiva nas duas esp?cies, e n?o houve diferen?a entre f?meas e machos quanto a massa dos corpos adiposos. Conclu?mos que xvi a segrega??o entre T. hispidus e T. semitaeniatus nesta ?rea de caatinga ocorre no uso vertical do espa?o, na maior vagilidade de T. hispidus na utiliza??o de micro-h?bitats e maior amplitude de tamanho de seus itens alimentares. Adicionalmente, diferen?as sazonais significativas em rela??o ao per?odo de atividade, temperatura corp?rea, e comportamentos de forrageamento e termorregulat?rio entre essas duas esp?cies de Tropidurus, possibilitam a coexist?ncia.

Pour étudier l'impact des changements environnementaux dans un écosystème marin côtier, il est nécessaire d'utiliser des espèces indicatrices. Il est essentiel de distinguer les performances de recherche de nourriture qui résultent des changements de l’environnement. L'objectif de ma thèse était d'étudier l'influence des facteurs intrinsèques et extrinsèques sur l'activité de recherche alimentaire des manchots pygmée (Eudyptula minor). J'ai démontré que la thermocline a permis aux oiseaux d'approcher le comportement optimal. Cependant, la thermocline est un élément instable. Je n'ai trouvé aucun effet des caractéristiques des individus sur le comportement et le succès. Mon travail suggère que les conditions environnementales sont les principaux facteurs qui influencent le comportement des manchots pygmée qui sont donc de bons indicateurs. / To study the impact of environmental changes in a coastal marine ecosystem, it is necessary to use indicator species. It is crucial to understand the foraging performances that proceed from environmental changes. The aim of my thesis was to examine the influence of intrinsic and extrinsic factors on the foraging activity of the little penguins (Eudyptula minor). The thermocline allowed birds to approach optimal behaviour. However, the thermocline is an unstable element. I did not find any effect of individual characteristics on their foraging behaviour and success. My work suggests that environmental conditions are major factors that will influence the behaviour of little penguins, allowing me to conclude that little penguins are good ecological indicators.

L’abeille domestique (Apismellifera) a un rôle majeur dans les écosystèmes naturels et agronomiques mais est exposée à un nombre croissant de pressions environnementales (nouveaux parasites, xénobiotiques, variations climatiques et malnutrition). Dans ce contexte, la compréhension des phénomènes impliqués dans les réponses au stress ainsi que leurs coûts associés devient cruciale pour mieux appréhender l’impact de ces pressions sur les abeilles. L’émergence d’un stress perturbe généralement l’homéostasie de l’organisme qui doit mettre en place une cascade d’adaptations physiologiques et comportementales pour le surmonter. Cependant, du fait de son mode de vie social, il est raisonnable de penser que les réponses vont se faire dans l’intérêt du groupe et non plus seulement dans l’intérêt de l’individu. Afin de caractériser les réponses au stress et de déterminer leur spécificité en fonction de la nature du stimulus (xénobiotiques, immunitaire, thermique, social), j’ai adopté une approche multidisciplinaire en ciblant l’identification des modifications i) physiologiques associées à la division du travail, ii) du métabolisme énergétique, et iii) comportementales. J’ai démontré quequelque soit leur rôle social (nourrice, gardienne, butineuse), les abeilles répondent de la même manière à un stress donné, si celui-­ci est écologiquement pertinent (hyperthermie et stress immunitaire mais pas xénobiotique). Une tendance à la diminution des ressources énergétiques a également été observée suite à un stress suggérant une modification des performances comportementales. Afin de vérifier cela, je me suis concentrée sur l’activité de butinage; le vol chez les insectes étant un des processus physiologiques les plus coûteux du règne animal. Une altération des performances de butinage a été mise en évidence chez les abeilles soumises à un stress immunitaire avec une réorientation des préférences de butinage au dépens du pollen, plus coûteux àc ollecter et moins riche en ressource énergétique que le nectar ; ceci probablement pour pallier au coût énergétique du stress. En revanche, en réponse àune hyperthermie, une augmentation de l’activité de butinage a été observée mais sans engendrer un coût supplémentaire au niveau des ressources collectées.Ces résultats sont discutés à la lumière du coût énergétique du stress et des conséquences potentielles sur les performances des abeilles, qui infine pourrait perturber l’homéostasie énergétique de la colonie. / Honeybees (Apis mellifera), which play an important role in natural and agronomic ecosystems, are exposed to a growing number of environmental pressures(new parasites, pesticides, climatechangeand poor nutrition). In this context, deciphering the mechanisms underlying stress responses and their costs becomes crucial to better understand theim pact of these pressures. Stress usually represents a challenge to the homeostasis of a norganism. In response, a cascade of physiological and behavioural adaptations enables the organism to cope with the stress. However, dueto their sociallife style, we could suggest that stress response in honeybees will occurin the interest of the colony and not only in the interest of the individual. To characterise the stress response and determine its specificity according to the stimulus (xenobiotic, immune, thermal, social), I developed a multidisciplinary approach to identify changes in i) task-­related physiology, ii) energetic metabolism, and iii) behaviour. I demonstrated that, regardless of their social function (nurse, guard, forager), bees respond in the sameway to a given stress, if itis ecologically-­relevant (heat and immune stress but not pesticides). Atendencytoward decreas ingenergetic resources was also observed following stress exposure, which suggests changes in behavioural performance.In order to test this hypothesis, I analysed changes in foraging activity in response to stress, as insect flight is one of the most costly physiological processes in the animal kingdom. I found that for aging performances were affected by animmune stress : bees changed their foraging preferences at the expense of pollen, probably to reduce the stress energetic cost, given that pollen is more costly to collect and provides alower energetic return than nectar. In contrast, in response to heat stress, an increase in colony for aging activity was observed, without an additional cost on resource collection. These results are discussed in the light of stress energetic cost and its potential consequences onhoneybee performances, which could disrupt the colony’s energetic homeostasis.

L’océan austral est un écosystème fragile dont la dynamique est influencée par des variations climatiques qui vont structurer la distribution spatio-temporelle des ressources. L’objectif de cette thèse était d’étudier les stratégies d’acquisition des ressources en proies mises en place par l’éléphant de mer austral face aux contraintes énergétiques (coûts du transport et coûts d’accès à la ressource) et temporelles (temps passé au fond d’une plongée et limite de plongée aérobie) auxquelles il est soumis. L’utilisation d’un ensemble d’enregistreurs de données déployés sur ces animaux a permis de reconstruire en trois dimensions leur plongée, mais également de calculer leur effort de nage, le nombre de proies rencontrées ainsi que leur dépense énergétique. Notre étude montre qu’à l’échelle d’une plongée, les éléphants de mer adaptent leur trajectoire, mais également le temps qu’ils passent au fond, en fonction du nombre de proies rencontrées. Pour des densités locales de proie importantes, ils passent plus de temps au fond, et concentrent leur recherche en zone restreinte, caractérisée par une diminution de la vitesse et une augmentation de la sinuosité horizontale. Au-delà de 550 m, le coût d’accès aux ressources devient supérieur aux coûts d’acquisition ; ils doivent alors faire face à un compromis entre l’accessibilité et la disponibilité en proies. À mesure qu’ils s’alimentent, ces phoques augmentent leur flottabilité, diminuant de surcroît leur dépense énergétique. Cette étude démontre également une structuration spatio-temporelle de cette dépense énergétique qui semble être liée au succès d’alimentation et donc à la distribution des ressources en proies. / The Southern Ocean is a fragile ecosystem whose dynamics are influenced by climate change that will structure the spatio-temporal distribution of resources. The objective of this PhD was to investigate the foraging strategies used by the southern elephant seal, under energetic (cost of transport and costs of access to the resource) and temporal (time at the bottom of a dive and aerobic dive limit) constraints. Using a set of animal-borne data loggers allowed us to reconstruct their three-dimensional path underwater, but also to calculate their swimming effort, the number of prey encountered and their energy expenditure. At the dive level, our study shows that elephant seals adapt their path, but also the time spent at the bottom, depending on the number of prey encountered. For high local prey density, they spent more time at the bottom, and concentrated their foraging effort in areas restricted search, characterized by a decrease in speed and an increase in horizontal sinuosity. Beyond 550 m, the cost of access to resources becomes greater than the cost of acquisition ; they must therefore deal with a trade-off between prey accessibility and availability. While feeding, these seals increase their buoyancy, reducing furthermore their energy expenditure. This study also shows a spatio-temporal structure of the energy expenditure that appears to be related to feeding success and therefore to prey resources distribution.

Le compromis d’allocation de l’énergie entre les fonctions concurrentielles de la reproduction et de la maintenance (et à long terme la survie) est largement tributaire de la capacité de l’organisme à acquérir des ressources dans son milieu. Les mécanismes physiologiques sousjacents aux décisions d’acquisition et d’allocation de l’énergie sont actuellement peu connus. Le but de cette thèse est d’étudier le rôle de deux hormones, la corticostérone et la prolactine, dans ces prises de décisions chez un oiseau marin longévif, le manchot Adélie (Pygoscelis adeliae), et ce, pendant une phase couteuse en énergie : la période d’élevage des poussins. Pour ce faire, nous avons conduit des approches expérimentales couplant d’une part la manipulation hormonale (augmentation des niveaux de corticostérone ou diminution des niveaux de prolactine) et la mesure du comportement en mer grâce à l’utilisation d’enregistreurs miniaturisés de l’effort de plongée. Par ailleurs, le budget temps, la condition corporelle, le régime alimentaire (analyses des isotopes stables du carbone et de l’azote) ainsi que le succès de reproduction des individus ont été considérés. A l’échelle de la plongée, nous avons observé des rôles positifs et négatifs de la corticostérone et de la prolactine, respectivement, sur le comportement de recherche alimentaire. De façon contradictoire, il semble que la corticostérone ait eu un effet négatif à plus large échelle (e.g. diminution de la durée des voyages alimentaires). La complexité de l’implication de ces deux hormones dans le compromis entre survie et reproduction est finalement discutée à la lumière de ces résultats. / The trade-off in the allocation of energy between the competitive functions of reproduction and maintenance (and survival in the long term basis) is largely dependent on the capacity of organisms to acquire resources in its environment. However, physiological mechanisms underlying decisions of energy acquisition and allocation are currently poorly known. Theaim of this PhD is to examine the role of two hormones, corticosterone and prolactin, in these decision processes in a long-lived seabird, the Adélie penguin (Pygoseclis adeliae) during an energetically costly period: the chick-rearing stage. To achieve this, we conducted experimental approaches coupling hormonal manipulation (increasing corticosterone levels ordecreasing prolactin levels) and the monitoring of at-sea behaviour by using miniaturised time-depth recorders. Moreover, time budget, body condition, diet (via stable isotopes analyses) and reproductive success of individuals were considered. At the dive scale, we observed positive and negative roles of corticosterone and prolactin on the foraging behaviour, respectively. However on the contrary, it seems that corticosterone had a negative effect at a larger scale (e.g. a decrease in at-sea trip duration). The complexity of the involvement of these hormones in the trade-off between survival and reproduction is discussed in the light of these results.

The microbiome plays a key symbiotic role in maintaining host health and aids in acquiring nutrients, supporting development and immune function, and modulating behavior. However, more research is needed to elucidate the potential impact of environmental pollutants on host microbial communities and how microbiomes can modulate the toxicity of contaminants to the host. Through a literature review of 18 studies that assessed the impacts of various anthropogenic chemicals on fish-associated microbiomes, we found that toxicants generally decrease microbial diversity, which could lead to long-term health impacts if chronically stressed, and can increase the host’s susceptibility to disease as well as the chemical resistance of certain microbes. These findings led us to explore the impacts of one of the reviewed contaminants, polycyclic aromatic hydrocarbons (PAHs), typically found in oil. The Deepwater Horizon disaster of April 2010 was the largest oil spill in U.S. history and had catastrophic effects on several ecologically important fish species in the Gulf of Mexico (GoM). This study tested the hypotheses that exposure to weathered oil would cause significant shifts in fish gut-associated microbial communities, with taxa known for hydrocarbon degradation increasing in abundance and that foraging behavior would decrease, potentially due to microbial dysbiosis via the gut-brain axis. We characterized the gut microbiome (with 16S rRNA gene sequencing) of a native GoM estuarine species, the sheepshead minnow (Cyprinodon variegatus). Fish were exposed to High Energy Water Accommodated Fractions (HEWAF; tPAH = 80.99 ± 12.5 μg/L) of oil over a 7-day period and whole gastrointestinal tracts were sampled for microbiome analyses. A foraging behavioral assay was used to determine feeding efficiency before and after oil exposure. The fish gut microbiome did not experience any significant changes in alpha or beta diversity but known hydrocarbon degrading taxa were noticeably present in oil-exposed communities and were absent in controls. We found the order Pseudomonadales, the family Paenibacillaceae, and Pseudomonas pachastrellae to be among these, with Pseudomonadales increasing in abundance. Foraging behavior was not significantly affected by oil exposure. This work highlights the need for further research to elucidate the functional metagenomic responses of the fish gut-microbiome under oil spill conditions.

Les changements climatiques ont un impact certain sur les écosystèmes marins. Un déplacement vers le sud des principaux systèmes de front servant de sites de nourrissage pour de nombreuses espèces de prédateurs supérieurs est susceptible de se produire dans les zones subantarctiques. Les « central place foragers », tels que les pinnipèdes, sont susceptibles de faire face à une augmentation de la distance entre leurs lieux d'alimentation et leurs colonies d'élevage. Nous avons étudié l’impact des changements climatiques sur le succès d’élevage et la dynamique de population des otaries à fourrure (Arctocephalus gazella) des Îles Kerguelen par le biais du développement du modèle individu centré, MarCPFS (Marine Central Place Foragers Simulator) qui montre que la survie du couple femelle-jeune est particulièrement sensible à la répartition des proies (abondance et structure), à la capacité de mémorisation des meilleurs sites de nourrissages trouvés par la femelle pendant la période d'élevage, à la taille des femelles et à la distance qu'il faut parcourir pour trouver la ressource. Les résultats suggèrent qu’au cours des trois prochaines décennies un déplacement vers le sud supérieur à 2km an 1 pourrait compromettre la survie et la durabilité des populations. Un couplage avec un modèle de simulation de la dynamique océanique et de la ressource (SEAPODYM) a permis des projections jusqu’à la fin de ce siècle basées sur le scénarios RCP8.5 du GIEC (2014), confirmant les tendances mises à jour précédemment. Ces travaux montrent que les perspectives de maintien des populations sont pessimistes y compris en envisageant une adaptation de la taille des individus. / Climate change has certain impact on the marine ecosystems. A southward shift in productive frontal systems serving as the main foraging sites for many top predator species is likely to occur in the Subantarctic areas. Central place foragers, as seabirds and pinnipeds, are thus likely to cope with an increase in the distance between foraging locations and their land-based breeding colonies. We studied the impact of climate change on the breeding success and population dynamics of Antarctic fur seals (Arctocephalus gazella) at Kerguelen Islands by means of an individual based model we developped, MarCPFS (Marine Central Place Foragers Simulator) which showed that the survival of the female-pup pair is particularly sensitive to the distribution of preys (abundance and structure), to the memorization abilities of the best resource sites found by the female during the rearing period, to the female size and to the foraging distance which it is necessary to cover at each trip. The results suggest that during the next three decades a southward shift greater than 2 km year-1 could compromise the survival and the sustainability of the populations. A coupling with a model of simulation of the oceanic dynamics and the resource (SEAPODYM) allowed projections till the end of this century based on scenarios RCP8.5 of the IPCC (2014), confirming the trends previously obtained. Globally, these works lead us to conclude with pessimistic perspectives about the sustainability of populations even when considering an evolution through time towards individuals of greater sizes.

The aim of this project is to investigate a cultural history of mushroom collecting in Sweden from the 19th century to the present with a focus on connections between aesthetics and the environment.  Collecting is defined broadly as gathering, storing, and accumulating.  This definition encompasses mycologists, mushroom enthusiasts, botanists, and natural historians documenting and preserving as many species as possible.  But it also includes collecting in the sense of leisurely mushroom collectors taking a part of the environment home with them to eat, store, or learn from. A history of mushroom collecting in Sweden is framed that does not only focus on edible mushrooms or scientific value, but emphasizes their linkages to place, memory, conservation, sociality, and embodied knowledge. Mushroom aesthetics are a starting point for exploring wider human connections to the environment and human perceptions of nature.   Collecting is presented as a process which is argued to be a means for constant dialogue with the environment. The cyclical collecting process is broken into stages that are discussed in designated chapters: Hunting, Identification and Assessment, and Storage and Sharing. Aesthetic aspects of mushroom collecting in Sweden are examined within these stages applying visual and discourse analyses to archival images, questionnaires, historic cookbook recipes, and mushroom identification books. Importance is also assigned to fully immersed aesthetic experiences and specific sensory stimuli that facilitate interconnection with non-human actors. Immersed aesthetic experiences are argued to be significant in their ability to democratize aesthetic appreciation of nature, in contrast to historical associations of aesthetics with taste and high culture. Fluctuating historical judgments are mapped about mushrooms, highlighting the framing of nature as a productive asset. Mushroom exhibitions are shown to be a point of collective meaning making, where aspects of natural time according to mushrooms challenge anthropocentric notions of temporality. This thesis through its focus on aesthetics in mushroom collecting reveals spaces of uncertainty and dynamic fluctuation in human-nature relationships, as well as a sense of value for being physically present and part of environments.