Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Pinnipeds are marine mammals of the Carnivora order. Some species were close to the complete extinction due to predatory hunt for their skin and blubber. Conservation measures have been taken to avoid extinction and population monitoring is essential to evaluate how populations are responding along the years. Remote sensing, from satellite images and aerial photographs, allows the monitoring through individual counting without interfering directly in the animals. The main objective of this work is to analyze aspects of the demography and the distribution of pinnipeds in the Elephant Island, located northeast of the Antarctic Peninsula, in the South Shetlands Islands, during the Austral summer (November to March) in the years of 2005 to 2010, using aerial censuses performed around the Elephant Island. The aerial censuses photographs were taken from Squirrel helicopters of the Brazilian Navy flying at a constant speed, 30 to 50 meters height along the island s perimeter. The data were obtained by counting the individuals registered in the photographs. The counting of all censuses summed 27.592 individuals along the years. Due to the fact that it was not possible to cover the totality of the island s perimeter in all censuses, the distribution and occurrence were studied dividing the island into seven sectors along its total perimeter. In general, the species observed more frequently in all sectors were the Southern elephant seals (Mirounga leonina) and Antarctic fur seals (Artocephalus gazella). Even though other seals species such as the Weddell seal (Leptonychotes weddelli), the leopard seal (Hydrurga leptonyx) and the crabeater seal (Lobodon carcinophaga) registered to the Elephant Island exhibited low representativeness in their occupancy, their presence is constant in all censuses. Using the statistical technique Principal Coordinates Analysis, we notice that the occupancy pattern of the Elephant Island by the pinnipeds is related to the substrate present in the different sectors of the island and to the period of the Austral summer sampled. Southern elephant seals settle in sectors of sandy substrate and exhibit the largest occupation during the earlier months of summer (November and December), while Antarctic fur seals preferably settle in rocky substrates and its occupancy is larger during the latest months of summer (January to February). New breeding sites were described in particular for the Antarctic fur seals in so called sectors of Valentin and Piloto Pardo. Preliminary data taken from satellite images of Valentin sector corroborated the aerial photograph data and indicated that the Antarctic fur seals are the predominant species in this region. To our knowledge, this is the first study taken with aerial censuses data in the Elephant Island, and the results presented here have great use for the correct management and conservation politics for the pinnipeds. / Pinípedes são mamíferos marinhos pertencentes à Ordem Carnívora. Algumas espécies foram levadas quase à extinção devido à caça por sua pele e gordura. Medidas de conservação foram tomadas para evitar a extinção e o monitoramento das populações é essencial para avaliar como estas estão reagindo ao longo dos anos. O sensoriamento remoto através de imagens de satélite e fotografias aéreas permite este monitoramento através da contagem dos indivíduos sem interferir diretamente com os animais. Este trabalho tem por objetivo geral analisar aspectos da distribuição e ocorrência de pinípedes na Ilha Elefante, situada a nordeste da Península Antártica no Arquipélago das Shetlands do Sul, durante o verão austral (novembro a março) entre os anos de 2005 a 2010 através de censos aéreos realizados no entorno da Ilha Elefante. As fotografias de censo aéreo foram tomadas a partir de helicópteros Esquilo da Marinha do Brasil voando em velocidade constante, entre 30 e 50 m de altura ao longo do perímetro da ilha. Os dados foram obtidos através da contagem de indivíduos registrados nas fotografias. Os animais contados a partir dos censos somados atingiram 27.592 indivíduos ao longo dos anos. Devido ao fato de que não foi possível cobrir todo o perímetro da ilha em todos os censos aéreos, a distribuição e abundância foram estudadas dividindo-se a ilha em sete setores ao longo de seu perímetro total. Em geral, as espécies observadas com maior frequência em todos os setores foram os elefantes-marinhos do sul (Mirounga leonina - EMS) e os lobos-marinhos antárticos (Artocephallus gazella - LMA). Ainda que os demais focídeos como a foca-de-Weddell (Leptonychotes weddelli), foca-leopardo (Hydrurga leptonyx) e a foca-caranguejeira (Lobodon carcinophaga) registrados para a Ilha Elefante apresentem baixa representatividade na sua ocupação, sua presença é constante em todos os censos. Utilizando técnica estatística de Análise de Coordenadas Principais, nota-se que o padrão de ocupação da Ilha Elefante pelos pinípedes está relacionado com o substrato presente nos diferentes setores da ilha. Os EMS permanecem em locais de substrato arenoso e apresentam maior ocupação nos primeiros meses do verão (novembro e dezembro), enquanto os LMA permanecem preferencialmente em locais rochosos e sua ocupação é maior nos últimos meses de verão (janeiro e fevereiro). Novos locais de reprodução foram descritos em especial para LMA nos setores denominados de Valentin e Piloto Pardo. Dados preliminares tomados a partir de uma imagem de satélite para o setor de Valentin corroboraram os dados de fotografias aéreas e indica que LMA é a espécie predominante dessa região. Ao nosso conhecimento, esse é o primeiro estudo realizado com dados de censo aéreo na Ilha Elefante e os resultados apresentados aqui tem grande utilidade para o correto manejo e para as políticas de conservação de pinípides.

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.

South Georgia is renowned for the abundance of Antarctic krill (Euphausia superba) and a range of krill predators. Variability in krill availability at a range of scales, and the consequences of this for predator-prey interactions, mean that quantifying the spatially explicit demand for krill by those predators is essential to understanding the mechanisms underlying ecosystem changes in the region. In this thesis demand within a distinct study box to the northwest of the island has been assessed. The thesis has three sections; (1) the number of predators; (2) the distribution of predators; and (3) the demand for krill by those predators. (1) Predator densities with confidence intervals were determined from appropriately designed shipboard transect survey; counts of Antarctic fur seals (Arctocephalus gazella), macaroni penguins (Eudyptes chrysolophus), gentoo penguins (Pygoscelis papua), and Antarctic prions (Pachyptila desolata) were adjusted for sea state, distance from observer and dive behaviour. Providing the first at-sea predator density estimates for the region. (2) A comparison of the distribution of female Antarctic fur seals engaged in pup-rearing (using satellite telemetry) and the whole population that were not restricted to a single part of the population (from shipboard transect survey) was undertaken. Using two general additive models based on the relationship between seal distribution (one derived from transect and the other from telemetry) and the physical environment indicated that the spatial distribution of lactating females is representative of the general population. (3) Using the derived predator density, the local krill demand estimate was 2581 tonnes krill per day, a consumption rate of 0.45% per day of the concurrently estimated krill biomass (using shipboard acoustics). Antarctic fur seals accounted for 75% of this demand. This level of demand was less than the increase in biomass resulting from krill growth. However, based on the length-specific demand, determined from concurrent predator diet samples demand exceeded growth for krill >48mm.