977 resultados para European Atlantic


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Scyphomedusae are receiving increasing recognition as key components of marine ecosystems. However, information on their distribution and abundance beyond coastal waters is generally lacking. Organising access to such data is critical to effectively transpose findings from laboratory, mesocosm and small scale studies to the scale of ecological processes. These data are also required to identify the risks of detrimental impacts of jellyfish blooms on human activities. In Ireland, such risks raise concerns among the public, but foremost amongst the professionals of the aquaculture and fishing sectors. The present work looked at the opportunity to get access to new information on the distribution of jellyfish around Ireland mostly by using existing infrastructures and programmes. The analysis of bycatch data collected during the Irish groundfish surveys provided new insights into the distribution of Pelagia noctiluca over an area >160 000 km2, a scale never reached before in a region of the Northeast Atlantic (140 sampling stations). Similarly, 4 years of data collected during the Irish Sea juvenile gadoid fish survey provided the first spatially, explicit, information on the abundance of Aurelia aurita and Cyanea spp. (Cyanea capillata and Cyanea lamarckii) throughout the Irish Sea (> 200 sampling events). In addition, the use of ships of opportunity allowed repeated samplings (N = 37) of an >100 km long transect between Dublin (Ireland) and Holyhead (Wales, UK), therefore providing two years of seasonal monitoring of the occurrence of scyphomedusae in that region. Finally, in order to inform the movements of C. capillata in an area where many negative interactions with bathers occur, the horizontal and vertical movements of 5 individual C. capillata were investigated through acoustic tracking.

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This study on the ecology of Irish hedgehogs (Erinaceus europaeus) has provided information on detection techniques, home range, habitat selection, hedgehog prey, nesting, courtship, genetics, road mortality, parasites, ageing and morphology of this species. Data were obtained from a focal study area in rural Cork, in which 24 radio tagged hedgehogs were monitored from June 2008 to June 2010. Further data were obtained through road kill surveys and the collection of hedgehog carcasses from around Ireland. Hedgehogs of both sexes were found to display philopatry. Habitat was not used in proportion to its availability, but certain habitats were selected and a similar pattern of habitat selection was evident in successive years. Hedgehogs preferred arable land in September and October and, unlike studies elsewhere, were observed to forage in the centre of fields. Badgers were regularly seen at the study site and did not appear to negatively affect hedgehogs’ use of the area. Instead the intra- and inter-habitat distribution of hedgehogs was closely correlated with that of their potential prey. Male hedgehogs had a mean annual home range of 56 ha and females 16.5 ha, although monthly home ranges were much more conservative. Male home range peaked during the breeding season (April-July) and a peak in road deaths was observed during these months. The majority of road kill (54%) were individuals of one year old or less, however, individuals were found up to eight and nine years of age. Genetic analysis showed a distinct lack of genetic variation amongst Irish hedgehogs and suggests colonisation by a small number of individuals. The ectoparasites, Archaeopsylla erinacei, Ixodes hexagonus and Ixodes canisuga were recorded in addition to the endoparasites Crenosoma striatum and Capillaria erinacei. In light of the reported decline in many areas of the hedgehogs’ range, it is a species of conservation concern, and this is the first study examining the ecology of the hedgehog in Ireland.

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Research investigating the position of women in management has, largely, been confined within national boundaries. Over the last fifteen years, empirical studies of women in international management have been undertaken, predominantly in North America. In this research field, many questions remain unanswered or have been only partially addressed. The particular focus of this study is on the senior female international managerial career move in Europe — a relatively unexplored area. Fifty senior female expatriate managers were interviewed, representing a wide range of industry and service sectors. The study, for the first time, assesses an exclusively senior sample of female managers who have made at least one international career move. This study of senior females in international management makes a theoretical contribution, not only to the analysis of gender and international human resource management, but also to wider debates within the contemporary women in management and career theory literatures. The aims of the study were to develop an understanding of the senior female international career move in a European context in order to more fully understand both the covert and overt barriers that may limit women’s international career opportunities. The results of the study show that the senior international career move has largely been developed along a linear male model of career progression, a development which, taken together with gender disparity both in organisations and family responsibilities, frequently prevents women employees from reaching senior managerial positions. The study proposes a model of the senior female international managerial career move, thereby contributing primarily to the international human resource management literature. The implications of the study for research literatures in women in management and career theory are also explored and a future research agenda developed.

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European badgers (Meles meles) are an important part of the Irish ecosystem; they are a component of Ireland’s native fauna and are afforded protection by national and international laws. The species is also a reservoir host for bovine tuberculosis (bTB) and implicated in the epidemiology of bTB in cattle. Due to this latter point, badgers have been culled in the Republic of Ireland (ROI) in areas where persistent cattle bTB outbreaks exist. The population dynamics of badgers are therefore of great pure and applied interest. The studies within this thesis used large datasets and a number of analytical approaches to uncover essential elements of badger populations in the ROI. Furthermore, a review and meta-analysis of all available data on Irish badgers was completed to give a framework from which key knowledge gaps and future directions could be identified (Chapter 1). One main finding suggested that badger densities are significantly reduced in areas of repeated culling, as revealed through declining trends in signs of activity (Chapter 2) and capture numbers (Chapter 2 and Chapter 3). Despite this, the trappability of badgers was shown to be lower than previously thought. This indicates that management programmes would require repeated long-term efforts to be effective (Chapter 4). Mark-recapture modelling of a population (sample area: 755km2) suggested that mean badger density was typical of continental European populations, but substantially lower than British populations (Chapter 4). Badger movement patterns indicated that most of the population exhibited site fidelity. Long-distance movements were also recorded, the longest of which (20.1km) was the greatest displacement of an Irish badger currently known (Chapter 5). The studies presented in this thesis allows for the development of more robust models of the badger population at national scales (see Future Directions). Through the use of large-scale datasets future models will facilitate informed sustainable planning for disease control.

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The wave energy industry is progressing towards an advanced stage of development, with consideration being given to the selection of suitable sites for the first commercial installations. An informed, and accurate, characterisation of the wave energy resource is an essential aspect of this process. Ireland is exposed to an energetic wave climate, however many features of this resource are not well understood. This thesis assesses and characterises the wave energy resource that has been measured and modelled at the Atlantic Marine Energy Test Site, a facility for conducting sea trials of floating wave energy converters that is being developed near Belmullet, on the west coast of Ireland. This characterisation process is undertaken through the analysis of metocean datasets that have previously been unavailable for exposed Irish sites. A number of commonly made assumptions in the calculation of wave power are contested, and the uncertainties resulting from their application are demonstrated. The relationship between commonly used wave period parameters is studied, and its importance in the calculation of wave power quantified, while it is also shown that a disconnect exists between the sea states which occur most frequently at the site and those that contribute most to the incident wave energy. Additionally, observations of the extreme wave conditions that have occurred at the site and estimates of future storms that devices will need to withstand are presented. The implications of these results for the design and operation of wave energy converters are discussed. The foremost contribution of this thesis is the development of an enhanced understanding of the fundamental nature of the wave energy resource at the Atlantic Marine Energy Test Site. The results presented here also have a wider relevance, and can be considered typical of other, similarly exposed, locations on Ireland’s west coast.

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The black scabbardfish is a deep water species that supports commercial fisheries across a large area of the NE Atlantic shelf. The life history of black scabbardfish is poorly understood and a major unresolved issue is population structure. In this study it was used a combination of methodologies to get further knowledge in the life history and population structure of A. carbo over its wide distribution range in the Northeast Atlantic. The new knowledge acquired during this study, will increase our ability to better manage this species in the NE Atlantic. It has been postulated that fish caught to the west of the British Isles are pre-adults that migrate further south (to Madeira) for spawning, implying a single panmictic population. In this study, specimens of Aphanopus carbo were sampled between September 2008 and May 2010 from two different areas: NW Scotland (French trawlers and deep water surveys) and Madeira Islands (longliners commercial landings). Geographical differences in reproductive state of scabbardfish were evident, supportive of a north-south migration theory. In the northern area, all specimens found were immature, while in Madeira all maturity stages were observed. In Madeira, spawning occurred during the fourth quarter, with peak maturity in October (males) and in November (females). The age of this species has proven difficult and has led to different and contradictory age and growth estimates. For this study, we used two reading interpretations to determine age and estimate the growth parameters. To the west of the British Isles, specimens reached a lower maximum age and had a higher growth rate than those caught off Madeira. These differences are consistent with the theory of a single population of black scabbardfish in the NE Atlantic, highly segregate, with smaller, immature and younger fish caught to the west of the British Isles and bigger and mature caught in Madeira Islands. The feeding ecology showed strong evidence that the diet of black scabbardfish is associated with the spawning migration of blue whiting, which may support a northerly feeding migration theory for black scabbardfish. The stable isotope analyses in the muscle of black scabbardfish identified that black scabbardfish feeds on species with epipelagic and benthopelagic affinities. Comparison with stable isotope analysis in Madeira samples indicated that black scabbardfish feed at a similar trophic level and has the same trophic niche width in both areas, assuming similar baseline isotope compositions. Otolith stable isotopes (oxygen - δ18O and nitrogen - δ15N) analyses were used as a tool to clarify migratory behaviour. Otolith isotope ratios can provide insight into whether adults caught around Madeira fed in an isotopically depleted northerly ecosystem (NW Scotland) during their pre-adult period and then migrate towards south to spawn. Overall, the results support a south-north migration of pre adult fish from spawning areas around Madeira and a north-south migration from the west of Scotland to the spawning areas. Given its life cycle there is an urgent need that the management process recognizes the existence of a continuous widely distributed stock of black scabbardfish between the west of the British Isles and Madeira. The results highlight large scale dispersal in this species which needs to be treated as a highly migratory species and be managed as a single population.

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Hitherto, the majority of studies which have included the discussion of Viking glass beads have mainly focused on the assemblages from individual sites, with limited use of known parallels. Exceptions to this include recent publications regarding the Icelandic material and Callmer’s 1977 catalogue of the finds from mainland Scandinavia, now over thirty years old. Analysis of these finds from Ireland was, for the most part, non-existent. The aim of this research is to address this lack of analysis within Ireland, while incorporating the wider context of the beads within the Viking North Atlantic. The research thus examines the use of glass beads of diagnostically Scandinavian manufacture and import found in Ireland, particularly in relation to their context and distribution. The history of research from Ireland as well as from across the Viking world is considered and explored throughout the thesis, with critique of methods and discussions used. Focussed analysis of both published and unpublished material detailing artefacts from Scandinavia (especially Vestfold), Britain, Iceland, the Faroe Islands and L’Anse aux Meadows is presented within the thesis in order to provide the greater picture for the core section of the thesis, the glass beads found in Ireland. Three appendices are included within Volume 2, databases of the glass beads under discussion from Ireland, the Vestfold region graves in Norway and the topsoil finds from the Kaupang trading place, also located within Vestfold. These appendices therefore represent the first-hand analysis of glass beads by the author. In total, this research represents the most up-to-date analysis of Viking glass beads from Ireland and presents a new look at the patterns of use, trade and interpersonal contact that affected the everyday lives of individuals living within Viking Age Ireland.

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A notable feature of the surveillance case law of the European Court of Human Rights has been the tendency of the Court to focus on the “in accordance with the law” aspect of the Article 8 ECHR inquiry. This focus has been the subject of some criticism, but the impact of this approach on the manner in which domestic surveillance legislation has been formulated in the Party States has received little scholarly attention. This thesis addresses that gap in the literature through its consideration of the Interception of Postal Packets and Telecommunications Messages (Regulation) Act, 1993 and the Criminal Justice (Surveillance) Act, 2009. While both Acts provide several of the safeguards endorsed by the European Court of Human Rights, this thesis finds that they suffer from a number of crucial weaknesses that undermine the protection of privacy. This thesis demonstrates how the focus of the European Court of Human Rights on the “in accordance with the law” test has resulted in some positive legislative change. Notwithstanding this fact, it is maintained that the legality approach has gained prominence at the expense of a full consideration of the “necessary in a democratic society” inquiry. This has resulted in superficial legislative responses at the domestic level, including from the Irish government. Notably, through the examination of a number of more recent cases, this project discerns a significant alteration in the interpretive approach adopted by the European Court of Human Rights regarding the application of the necessity test. The implications of this development are considered and the outlook for Irish surveillance legislation is assessed.

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Communication is important for social and other behavioural interactions in most marine mammal species. The bottlenose dolphin (Tursiops truncatus, Montagu, 1821) is a highly social species that use whistles as communication calls to express identity and to initiate and maintain contact between socially interactive individuals. In this thesis, the degree of variability in whistle behaviour and whistle characteristics was examined between different habitats on a range of spatial scales. The whistle characteristics that best discriminated between different communities were investigated, along with exploration of whistle variation in relation to habitat type, levels of social interaction and relatedness. Finally, the use and variability of individually distinctive calls (signature whistles) within and between Irish and US waters were also examined. Relatively high levels of whistle variation were found within a genetically and socially isolated population of dolphins in the Shannon Estuary, reflecting the need for individual identification and distinctive whistles in a population with long term site fidelity and high levels of social cohesion. Variation between reproductively separate communities in Irish waters was relatively small except between animals in inshore compared with continental shelf waters. The greatest differences in whistle structure overall were evident between dolphins using inshore and offshore US waters, likely reflecting social isolation of the two distinct ecotypes that occur in these waters but also variation in behaviour or habitat conditions. Variation found among inshore communities in US waters reflected similarities in habitat use and levels of social interaction. These findings suggest that vocal variation is socially mediated, behaviourally maintained and dependent on levels of social contact between individuals. The findings contribute to our understanding of the interaction of factors influencing vocalisation behaviour in this behaviourally complex and ecologically plastic species.

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The parasite Bonamia ostreae has decimated Ostrea edulis stocks throughout Europe. The complete life cycle and means of transmission of the parasite remains unknown. The methods used to diagnose B. ostreae were examined to determine sensitivity and reproducibility. Two methods, with fixed protocols, should be used for the accurate detection of infection within a sample. A 13-month study of two stocks of O. edulis with varying periods of exposure to B. ostreae, was undertaken to determine if varying lengths of exposure would translate into observations of differing susceptibility. Oyster stocks can maintain themselves over extended periods of time in B. ostreae endemic areas. To identify a well performing spat stock, which could be used to repopulate beds within the region, hatchery bred spat from three stocks found in the North sea were placed on a B. ostreae infected bed and screened for growth, mortality and prevalence of infection. Local environmental factors may influence oyster performance, with local stocks better adapted to these conditions. Sediment and macroinvertebrate species were screened to investigate mechanisms by which B. ostreae may be maintaining itself on oyster beds. Mytilus edulis was positive, indicating that B. ostreae may use incidental carriers as a method of maintaining itself. The ability of oyster larvae to pick up infection from the surrounding environment was investigated by collecting larvae from brooding oysters from different areas. Larvae may acquire the pathogen from the water column during the process of filter feeding by the brooding adult, even when the parents themselves are uninfected. A study was undertaken to elucidate the activity of the parasite during the initial stage of infection, when it cannot be detected within the host. A naïve stock screened negative for infection throughout the trial, using heart imprints and PCR yet B. ostreae was detected by in-situ hybridisation.

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Many among the emerging generation of political elites in Africa see the role the European Union (EU) plays in the maintenance of an unprecedented period of peace in Western Europe as an inspirational example of the manner in which the African Union (AU) can contribute to peace and stability in Africa. This doctoral thesis examines security cooperation between the EU and the AU, with a particular focus on the nature and substance of that cooperation. It suggests that despite the establishment of various EU–AU institutions and ties with a role in security policy and cooperation, such security cooperation is limited in substance. This study argues that EU–AU security cooperation is especially constrained by the emergence of alternative partners, most notably China, and by failures of implementation and follow-through. Two case studies, the first dealing with EU–AU cooperation in peacekeeping, and the second addressing the silent water crisis along with the link between water and security, have been analysed in detail to determine the effectiveness and sustainability of the EU–AU partnership. A number of important lessons for regionalism, interregionalism and multilateralism are drawn from the bond between the EU and the AU. This doctoral thesis will prove that, despite an emphasis on the problematic term ‘strategic’ by both EU and AU policymakers, EU–AU cooperation is limited and somewhat lacking in strategic direction. The cooperation between the EU and the AU focuses mainly on EU financial support for AU peacekeeping and specific projects in Africa (e.g. in the water sector), as well as on a limited political dialogue. Nonetheless, the EU–AU link represents the most comprehensive partnership the AU has with any non-African actor. This study will furthermore demonstrate that the United Nations (UN) is an indispensable third-party to their relationship and it is therefore more appropriate to speak of the AU–EU–UN nexus. This doctoral thesis concludes that the AU–EU–UN nexus is an important example of interregionalism in a global context and that such interregionalism is an important emerging part of global governance.

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Polymorphic microsatellite DNA loci were used here in three studies, one on Salmo salar and two on S. trutta. In the case of S. salar, the survival of native fish and non-natives from a nearby catchment, and their hybrids, were compared in a freshwater common garden experiment and subsequently in ocean ranching, with parental assignment utilising microsatellites. Overall survival of non-natives was 35% of natives. This differential survival was mainly in the oceanic phase. These results imply a genetic basis and suggest local adaptation can occur in salmonids across relatively small geographic distances which may have important implications for the management of salmon populations. In the first case study with S trutta, the species was investigated throughout its spread as an invasive in Newfoundland, eastern Canada. Genetic investigation confirmed historical records that the majority of introductions were from a Scottish hatchery and provided a clear example of the structure of two expanding waves of spread along coasts, probably by natural straying of anadromous individuals, to the north and south of the point of human introduction. This study showed a clearer example of the genetic anatomy of an invasion than in previous studies with brown trout, and may have implications for the management of invasive species in general. Finally, the genetics of anadromous S. trutta from the Waterville catchment in south western Ireland were studied. Two significantly different population groupings, from tributaries in geographically distinct locations entering the largest lake in the catchment, were identified. These results were then used to assign very large rod caught sea trout individuals (so called “specimen” sea trout) back to region of origin, in a Genetic Stock Identification exercise. This suggested that the majority of these large sea trout originated from one of the two tributary groups. These results are relevant for the understanding of sea trout population dynamics and for the future management of this and other sea trout producing catchments. This thesis has demonstrated new insights into the population structuring of salmonids both between and within catchments. While these chapters look at the existence and scale of genetic variation from different angles, it might be concluded that the overarching message from this thesis should be to highlight the importance of maintaining genetic diversity in salmonid populations as vital for their long-term productivity and resilience.