The heterogeneous landscape of Florida Bay provides habitats for a variety of predators and prey. This dissertation examined the bottom-up transfer of affects from environmental variability through prey composition up to competition and predation affects on top predator distribution and foraging ecology in Florida Bay. Line transect surveys for bottlenose dolphins and seabirds were conducted in Florida Bay during the summer months of 2002 - 2005. Photo-identification techniques were implemented to identify individual dolphins. Synoptic with this survey effort, habitat characteristics (temperature, salinity, dissolved oxygen, turbidity, chlorophyll a, depth and bottom type) and prey composition (bottom trawl or gillnet) were sampled. Comparison of envelope maps from generalized additive models determined that predictive capacity of dolphin habitat did not improve by incorporating fish distribution data. However, models of dolphin distribution based solely on environmental proxies of fish distribution resulted in high predictive capacity. During the 2005 summer, shark distribution was sampled using a longline. The abundance of sharks was only correlated to fish catch from trawls on a regional scale. Larger sharks, of species that may threaten dolphins, were only caught in the Gulf zone of the Bay. Analysis of dolphin distribution revealed high individual site and foraging tactic fidelity. Dolphins were spatially coincident with habitat characteristics that encouraged the use of each individual's preferred foraging tactic. Depth was identified as the primary variable determining dolphin foraging tactic choice. Depth plays a significant role in the benthic composition of Florida Bay, which subsequently impacts prey communities and affects dolphin distribution, foraging and social ecology. Ordinations determined that fish distribution was also principally affected by depth and bottom type. Shallow environments frequently corresponded with mudbank habitat (depth < 1m) where the sighting rates of seabirds (cormorants, osprey, pelicans, terns) and foraging dolphins peaked. In conclusion, subtle relief in South Florida's bedrock topography dramatically affect benthic composition within Florida Bay, providing patchy habitats for prey and predators. The Florida Bay ecosystem will change with expected sea level rise, including spatial shifts of mudbank habitats. Top predator populations in Florida Bay will be forced to modify their distribution and foraging ecology accordingly. / Dissertation

Harmful algal blooms (HABs) of the brevetoxin-producing dinoflagellate Karenia brevis occur periodically along the central west coast of Florida. Mass mortalities of marine birds have long been associated with these blooms, yet there is little data documenting the accumulation of brevetoxins in the tissues of birds and their prey items. An intense HAB event impacted the region from Tampa Bay to Charlotte Harbor during most of 2005. More than one hundred marine birds, representing twenty three species, were collected during this bloom. All birds sampled were found dead or had died within 24 hours of admittance to local wildlife rehabilitation centers. In order to determine if fish were vectors for brevetoxin ingestion, the stomach contents of all birds were examined and any recovered fish were identified to the extent possible. The gastrointestinal tissues and contents from all avian samples were analyzed for brevetoxin levels, with results ranging from Shorebirds and gulls may also be exposed to brevetoxins via scavenging of red tide-killed fish deposited on beaches during blooms. Samples from scavenged fish were found to have brevetoxin levels ranging from 31 to 95,753 ng PbTx per gram tissue.

Speciation is an important process that is responsible for the generation of biodiversity on Earth. The importance of gene flow during speciation is hotly debated; however, it can be investigated by studying the process of intraspecific population differentiation. Here, I investigate the mechanisms that influence population differentiation and gene flow in brown (Sula leucogaster) and red-footed boobies (S. sula). These species are congeneric, broadly sympatric, and ecologically similar; however, they differ in their marine habitat preference (inshore vs. pelagic). I hypothesized that: (i) gene flow is restricted by major physical barriers in both species, and (ii) gene flow in the absence of physical barriers is more prevalent in red-footed boobies due to their pelagic marine habitat preference. First, I characterized the structure and function of the booby mitochondrial genome. Using extensive DNA sequencing and phylogenetic methods, I found that boobies have tandemly duplicated mitochondrial control regions that evolve in concert. I suggest that concerted evolution of duplicated control region may be common in seabirds. To quantify matrilineal population genetic structure and gene flow, I sequenced one control region in 513 brown and red-footed boobies. Both species exhibited strong population genetic structure that was attributable to continental barriers to gene flow such as the Isthmus of Panama. In the absence of physical barriers, gene flow was more prevalent in red-footed boobies. I also used microsatellite and nuclear intron loci to perform multilocus phylogeographic analyses of brown and red-footed boobies. Individuals of both species could be grouped into four genetic populations that corresponded to oceanographic regions. In red-footed boobies, gene flow following secondary contact of previously isolated lineages was common, perhaps due to a pelagic habitat preference. In brown boobies, major genetic populations apparently diverged in the absence of gene flow. Despite this, Isla San Benedicto in the Eastern Pacific is a site of secondary contact between brown booby lineages that diverged approximately one million years ago, and hybrids are apparently fertile. These findings suggest that gene flow following secondary contact may be an important, but overlooked, component of speciation. / Thesis (Ph.D, Biology) -- Queen's University, 2012-04-28 17:28:53.302

Los hábitats reproductivos y de alimentación, los patrones de movimientos, así como los recursos alimenticios y las condiciones nutricionales y corporales son factores clave en la historia de vida de las aves marinas que se interrelacionan e influyen en el desarrollo reproductivo. Se estudiaron estas características en los skuas pardos (Stercorarius antarcticus lonnbergi) que reproducen en Península Potter, Isla 25 de Mayo, Islas Shetland del Sur, Antártida, durante las temporadas 2012/13 y 2013/14. Esta población permanece en la zona entre octubre y abril y luego migra hacia el norte, y mientras permanece en su sitio reproductivo se alimenta principalmente en las colonias de pingüinos. El período reproductivo se dividió en tres etapas: incubación (In), cuidado temprano del pichón (Pi) y pichón volantón (Pv). En cada etapa se colocaron unidades GPS y luego de 10 días se los recuperó, se extrajo una muestra de sangre y se registró la masa corporal. Con los datos de posición se determinó el área de acción, la distancia de desplazamiento diario y el patrón de presencia de los padres a diferentes distancias del nido. Se estudió la dieta por medio del análisis de isótopos estables de C y N en células rojas y plasma. Además, se determinaron parámetros bioquímicos sanguíneos, las condiciones inmunológicas a través de la evaluación de frotis sanguíneos y se determinó el estado corporal por medio de un índice. El área de acción se redujo luego del nacimiento de los pichones y se expandió a la edad de emplume. El nivel de actividad indicado por la distancia de desplazamiento diario aumentó a lo largo del período reproductivo, como también lo hizo el tiempo que los skuas pardos dejaron el nido solo, lo cual se puede relacionar con las necesidades de cuidados y alimentación creciente de los pichones a medida que se desarrollan. En relación con el cambio en las características del movimiento mencionadas, durante el transcurso del período reproductivo hubo un aumento en el aporte de recursos marinos a la dieta, que puede estar vinculado con la disminución en la ingesta de grasas y el aumento en el consumo de reservas proteicas corporales. Este consumo de reservas corporales, sin embargo, no se reflejó en cambios en el estado corporal. La dieta y estado corporal y nutricional no mostraron diferencias entre los sexos. El estado inmunológico indicó un mayor nivel de estrés en las hembras, lo cual podría estar relacionado con su mayor tiempo de presencia en el nido. El resto de los parámetros de movimientos y uso del espacio no mostraron diferencias entre los sexos. Ni las características de los movimientos ni el patrón de presencia de los padres en el nido estuvieron relacionados con la probabilidad de éxito en la eclosión de huevos. De la misma manera, ni la dieta ni el estado corporal, nutricional o inmunológico mostraron relación con el éxito de eclosión. Sin embargo, cuando el comienzo de la reproducción de los pingüinos coincidió con el comienzo del período reproductivo de los skuas pardos, el éxito de eclosión estuvo relacionado con la sincronización entre la fecha de postura y el pico de postura de los pingüinos. Por el contrario, cuando los pingüinos comenzaron su reproducción en fechas más tempranas, la fecha de postura de los pingüinos no se vinculó con la probabilidad de éxito. Esto sugiere una fuerte dependencia del éxito reproductivo de los skuas pardos a la disponibilidad de alimento en las colonias de pingüinos. La necesidad de recuperación del estado corporal luego de la migración podría impedir adelantar el comienzo de su reproducción para mantenerse en fase con los pingüinos, y la necesidad de realizar una migración posterior podría empujarlos a abandonar el cuidado de los pichones, si hacerlo compromete su posibilidad de supervivencia futura. Nuevas investigaciones sobre la manera en que la cronología reproductiva de los pingüinos y la disponibilidad de alimento en ellas impactan sobre el éxito reproductivo de los skuas pardos, así como sobre el modo en que los movimientos y el comportamiento de los skuas influyen en la probabilidad de pérdida de nidos en etapa de incubación serían muy importantes frente a un escenario de cambio climático que podría modificar el período reproductivo de los pingüinos, y de bajo éxito reproductivo en los skuas pardos.

Climate change has a wide range of effects with the potential to cause broad changes in marine ecosystems. The Arctic is predicted to be one of the most highly impacted areas, with average temperatures increasing by as much as 3-5°C. As temperatures rise, Arctic sea ice is disappearing earlier each year, leading to changes in the ocean environment. Thick-billed murres (Uria lomvia) (TBMU) and northern fulmars (Fulmarus glacialis) were collected at colonies in the eastern Canadian Arctic to examine potential changes in Arctic marine food webs over the past three decades. Otoliths and invertebrates were examined in the murre stomachs, and the results compared to data collected from the same colonies in the 1970s and 1980s. Few changes were observed in the diets of the high Arctic thick-billed murres where the ice-associated Arctic cod continue to dominant the prey items found in the thick-billed murres. Significant changes were found in birds sampled from the low and mid-Arctic. In the low Arctic, Arctic cod has declined across all of the colonies sampled, while the capelin, which is a sub-Arctic species, has become dominant in the diets of the birds in the low Arctic and a common prey species mid-Arctic where it was not observed in the diet of TBMUs previously, indicating a northward expansion of this species. The proportion of invertebrate species has changed in some zones and mysids now constitute a large proportion of the murre diet in the low and mid Arctic where hyperid and gammarid amphipods used to be the main invertebrate consumed. The birds can be used as samplers of the marine environment, and as integrators of the environmental changes that are occurring, but prey were not the only items found in the stomachs on birds sampled. Marine plastic debris was also found in the stomach contents of both murres and fulmars from every colony sampled indicating plastic ingestion is becoming a widespread problem for Arctic seabirds. Plastics found in northern fulmars indicate that marine plastic debris is increasing in the Arctic Archipelago, and monitoring of this recognized indicator species of plastic debris will allow long term monitoring of man-made debris in Canada’s north. Plastic debris was also found in thick-billed murres from all of the colonies sampled. Although murres are not useful indicators of general marine plastic debris the presence of plastics at all the colonies sampled indicate that plastics are not just a problem for surface feeding seabirds, but a threat to a number of species found in Canadian waters.

Increasing exploitation of pelagic fish populations worldwide has often resulted in overfishing and the collapse of commercial fisheries and associated serious declines in many marine predator populations, including seabirds. These events highlight the competing demands for limited marine resources. Recent emphasis for the ecologically sustainable management of commercial fisheries has stimulated attempts to manage fisheries by incorporating knowledge of trophic interactions and ecosystem functioning, known as ecosystem-based fisheries management. Seabirds are often highly visible, wide-ranging upper trophic level consumers that aggregate in areas of increased ocean productivity and therefore be used as natural monitors of marine environmental conditions. Further, many seabirds commonly fed on commercially-exploited fish stocks (often targeting prey of similar size). In this study, the population dynamics of Australasian gannets (Morus serrator) breeding in Port Phillip Bay, Victoria, is investigated and competition between gannets and commercial fisheries is determined. In addition, the potential use of seabird reproductive and population parameters as indicators of the abundance of commercially exploited fish stocks, and pelagic conditions generally, is assessed.

Os vírus da influenza A (IA) provocam epidemias e pandemias em humanos. As aves selvagens são os reservatórios naturais desses vírus, dentre essas, as migratórias possuem um importante papel como transmissores da doença. A região subantártica abriga populações de aves marinhas, as quais reproduzem-se no verão austral formando colônias com milhares de aves, o que potencializa a importância do estudo do vírus IA em aves marinhas neste ambiente. Os objetivos deste trabalho foram analisar a presença do vírus IA em swabs orotraqueal e cloacal, e de anticorpos anti-IA em soro de aves marinhas da região subantártica, caracterizar molecularmente as amostras positivas, e conhecer mais a ecologia deste vírus. Foram coletadas amostras biológicas de pinguim-papua, pinguim-de-barbicha, pinguim-de-adelie, skua-subantártica, pomba-do-cabo, e petrel-gigante-do-sul, entre 2010-13, nas ilhas Elefante e Rei George. Das 615 amostras de swab, 13 foram positivas por One Step Real Time RT-PCR, e uma foi caracterizada como H6N8. Das 673 amostras de soro, 108 foram positivas por Ensaio Imonoenzimático competitivo (cELISA). O estudo contribuiu para o conhecimento do vírus IA na região e foram feitas recomendações para a prevenção a introdução de patógenos na Antártica. / Influenza A (IA) viruses cause epidemics and pandemics in humans. Wild birds are the natural reservoir of these viruses, among these, migratory ones have an important role as transmitters of disease. The subantarctic region is home to seabird populations, which breed in the austral summer forming colonies with thousands of birds, which enhances the importance of the study of AI viruses in waterfowl in this environment. The objectives of this study were to analyze the presence of IA virus in tracheal and cloacal swabs, and anti-IA antibodies in serum of seabirds from subantarctic region, molecular characterization of positive samples, and learn more about this virus ecology. Biological samples were collected of gentoo penguin, chinstrap penguin, adelie penguin, brown skua, cape petrel, and southern giant petrel, from Elephant and King George islands, between 2010-13.Of the 615 swab samples, 13 were positive by Real Time One Step RT-PCR, and one was characterized as H6N8. Of the 673 serum samples, 108 were positive by competitive enzyme-linked immunosorbent assay (cELISA). The study contributed to AI virus knowledge in the region and recommendations for preventing the introduction of pathogens in Antarctica were made.

O objetivo deste trabalho foi estudar a composição da avifauna aquática, a diversidade, suas abundâncias, a variação mensal e sazonal das populações e entender a relação desses fatores com a variação de maré na Laguna da Ilha Comprida. Ocorreram 6193 indivíduos referentes a 54 espécies, a diversidade de acordo com o Índice de Shannon foi 2,7036. Não houve diferença estatística no número total de indivíduos entre os meses e estações. Já a riqueza variou, sendo o maior valor na primavera, explicada pela ocorrência de espécies visitantes do hemisfério norte durante a migração para o sul. Houve correlação negativa entre a riqueza de espécies, número de indivíduos e diversidade, com a oscilação da maré, pois conforme a maré diminuía, aumentava a área disponível para descanso e forrageio. A Família Ardeidae apresentou correlação negativa mais forte em relação à amplitude de maré ao ser comparada as Famílias Scolopacidae e Charadriidae. Este fato ocorreu pela presença de Egreta caerulea que depende da maré baixa para forragear. A Laguna é uma importante área para avifauna aquática utilizada para alimentação e descanso, principalmente na maré baixa, além de ponto de parada para aves costeiras na migração para o sul durante a primavera. / The objectives of this work was to study the composition of aquatic bird, its diversity, abundance, monthly and seasonal variation of the bird populations and understand the relation of these factors with tidal variation at Laguna da Ilha Comprida Island. We registered 6193 individuals of bird referring to 54 species, being that the Shannon diversity index was 2,7036. There were not statistics difference between total number of individuals, the months and seasons. However there was variation of the species richness, being the biggest valor in the spring, explained for the occurrence of visiting species of north hemisphere during the migration for the south. There were negative correlation enters the species richness, individual number and diversity with the tidal oscillation. Because when the tide was low, increase the area available for rest and foraging. The Ardeidae family presented stronger negative correlation in relation of tidal variation when comparative being the Families Scolopacidae and Charadriidae. This fact occurred for the presence of Egreta caerulea that depends on the low tide to foraging. The Laguna is an important aquatic area for bird, used for feeding and rest, during the low tide and stopover for coastal birds in the migration for the south during the spring

Les espèces endothermes amphibies font face à de fortes contraintes durant leurs séjours en mer dont l’augmentation des coûts de thermorégulation. La recherche alimentaire du manchot royal (Aptenodytes patagonicus) s’étend sur plusieurs jours alternant des plongées profondes de chasse et des périodes de repos à la surface de l’eau correspondant à deux stratégies de thermorégulation différentes. Durant les plongées, l’hypothermie des tissus suggère une économie d’énergie visant à augmenter la durée d’apnée. Cependant, l’utilité de la réaugmentation des températures corporelles durant les périodes de repos reste méconnue. Alors que la digestion débute durant les plongées, nous supposons que le stockage des acides gras dans les tissus adipeux périphériques ne peut se faire que par le retour à normothermie de ces tissus. Nous avons testé cette hypothèse en maintenant des individus équipés d’enregistreurs de températures (périphériques et interne) dans une piscine d’eau de mer afin d’étudier les variations de températures en fonction de l’état nutritionnel des manchots. De plus, nous avons mesuré, par respirométrie, les dépenses énergétiques en fonction des températures corporelles. Enfin, nous avons étudié les variations de flux sanguins à l’aide de thermographie infra-rouge afin de comprendre le retour à normothermie des tissus périphériques et les coûts énergétiques associés. / The energetic cost of foraging activities in King Penguin (Aptenodytes patagonicus) consists to reach favourable areas, realizes depth diving to attempt fish patch and resting in high latitude cold water. Several studies have shown that resting in cold water could be represent a more expensive cost than realized depth diving. Indeed, this paradox is probably linked with contrasting thermoregulation processes. During daylight, a general hypothermia occurs and is believed to reduce energy expenditure. At sunrise occurs a re-warming to normothermia, contributing to increase heat-loss during the night. We hypothesise an energetic conflict between thermoregulation and digestive processes. During daylight, the organism may be unable to assimilate the end product of prey digestion (free fatty acids) inside the peripheral subcutaneous adipose tissues (SAT), because skin is no more blood perfused. During the night, re-warming and re-connecting to blood circulation peripheral tissues could be inevitable to end the assimilation of FFA inside the SAT. In a first step, we have reproduced the conditions of a resting night at sea and events of rewarming skin temperature, using a sea water tank in which king penguins equipped with internal temperature loggers were maintained several days. In a second step, we have tested a generalisation of our hypothesis studying body temperature variations on penguins fast and feed. Finally, we have measured the cost to maintain normothermia in cold water with respirometry measures and investigated peripheral vasodilation with body temperature variations and infrared thermography.

Mid-latitude shelf-seas are highly productive regions that host a rich diversity of animals including large numbers of marine mammals and seabirds. These large vertebrate predators play a crucial role in the functioning of shelf-sea ecosystems. However, the combined effects of multiple anthropogenic stressors are driving unprecedented declines in many of their populations. Mitigating this depends upon effective conservation and integrated ecosystem based approaches to management, which require a comprehensive understanding of the habitat needs of marine predators. The foraging efficiencies of marine predators are closely tied to the availability of a number of oceanographic features. As such, these physical habitats represent critical locations within a species’ range whose preservation and protection should be of high priority. The collection of studies presented in this thesis aims to improve our understanding of the physical oceanographic processes that underlie the at-sea behaviours and distributions of marine mammals and seabirds in coastal and shelf-sea environments. A combination of at-sea boat surveying, animal-borne biologging, satellite remote-sensing, passive acoustics and numerical modelling was used to collect information on the distributions and foraging behaviours of a range of marine predators alongside the bio-physical characteristics of the oceanographic habitats they occupied. These data were then used to (1) examine the use of oceanographic habitats generated around tidal-mixing fronts and coastal topographic structures by a range of piscivorous species including bottlenose dolphins Tursiops truncatus, common dolphins Delphinus delphis, harbour porpoises Phocoena phocoena and northern gannets Morus bassanus, and (2) identify the physical processes underlying their creation. Original aspects of this work include the examination of the fine-scale bio-physical mechanisms that link marine predators to tidal-mixing fronts and coastal tidal-topographic structures. Main findings indicate that offshore habitats around tidal-mixing fronts are used by both common dolphins and northern gannets for foraging. Individuals associated with patches of increased sub-surface primary productivity, which were generated via a bi-weekly cycle of episodic turbulent mixing and stratification following an adjustment in the spatial position of a front with the spring-neap cycle. Moreover, around fronts, the dives of gannets were likely to be short and of a V-shaped strategy (with little active swim phase), which likely reflects an increase in the accessibility and catchability of their prey. In a coastal estuarine system, bottlenose dolphins were shown to associate with predictable downwelling features generated during flood tidal flows that were thought to act as a foraging aid. Together, these findings highlight the fundamental role physical oceanographic processes play in the structuring of marine ecosystems by providing vulnerable marine predators with prosperous and reliable foraging resources that they can exploit. This work has implications for both future studies of marine predator foraging ecology and the management of anthropogenic activities in coastal and shelf-seas.