Linguagem, cultura e sociedade: abordagens linguísticas

Os artigos inseridos neste volume abrangem: um trabalho sobre o papel determinante que o factor motivacional pode desempenhar no processo de aprendizagem de uma língua; uma análise de marcadores de controlo de contacto na língua portuguesa em contexto de reuniões empresariais; uma abordagem do uso de estrangeirismos em processos de comunicação relacionados com três campos de actividade distintos; uma investigação sobre várias versões de traduções técnicas de inglês para português e as implicações decorrentes da sua falta de adaptação a diferentes realidades culturais e linguísticas; e, ainda, um estudo das dificuldades de compreensão do discurso científico e tecnológico enquanto factor de exclusão.Fundação para a Ciência e a Tecnologi

Zoogeographic and Richness Patterns in Southern Ocean Benthos

This thesis describes the large scale biogeographic patterns found in the Southern Ocean benthos. Using SOMBASE and SCAR-MarBIN, the two most comprehensive, georeferenced databases of Antarctic marine biodiversity ever compiled, a range of taxa were investigated but focusing on the Mollusca, Bryozoa and Pycnogonida. Over 8,000 species of marine invertebrates from over 5,000 sites constituting -34,000 records were used in the analyses. The strong faunal links between the Antarctic and South America were confirmed but I found little evidence for a biogeographical relationship between the Antarctic or South America and New Zealand or Tasmania. Regional levels of Southern Ocean endemism proved the influence of the Antarctic Circumpolar Current upon the distribution of Southern Ocean benthos. My study shows the Southern Ocean as a ‘single functional unit’ with no evidence for an earlier proposed biogeographical split between East and West Antarctica. Some general rules on Antarctic benthic biogeography are viable, including species endemism rates of around 50% and a definite distinction between the sub-Antarctic islands influenced by either South America or by New Zealand. In the context of potential shifts in species distribution with climate change I investigated the current ranges of selected Southern Ocean taxa (Mollusca, Amphipoda, Ophiuroidea and Hexacorala), and looked for hotspots of coinciding northern and southern geographic range limits. Southern Patagonia, South Georgia and Kerguelen had the greatest range-limit hotspots. Monitoring range shifts in these key places and taxa will enable us to track the influence and effects of climate change on benthic species distributions in the Southern Ocean

The Factors Affecting the Diets of Groundfish in the Gulf of Alaska : Ecological and Modeling Considerations

Marine systems undergo changes in community composition over time as a result of a variety of environmental and anthropogenic factors. Understanding these community changes and the factors that drive them is critical for ecosystem management of marine resources. The Gulf of Alaska (GOA) is a large marine ecosystem that includes a variety of species that support large scale fisheries. This is also a system in which large scale community shifts, or regime shifts, have occurred due to the Pacific Decadal Oscillation (PDO) and fishing pressure. Given the economic and conservation importance of this marine system, the GOA has been modeled using a variety of multispecies, or ecosystem, models. While this work has been critical in understanding the ecosystem dynamics of the GOA and helped generate management recommendations for commercial species, these models often make assumptions regarding trophic-dynamics, particularly that predator-prey relationships follow a standard functional response and do not change through time in response to environmental variables. However, empirical evidence suggests that a predator's diet can be influenced by a variety of factors, abiotic and biotic, at large and small spatial scales. Our overall objective was to investigate the potential impact environmental variables may have in structuring this ecosystem by using statistical analyses of diets and an ecosystem modeling framework. We focused on three commercially and ecologically important groundfish predators: Pacific Cod (Gadus macrocephalus), Pacific Halibut (Hippoglossus stenolepis), and Sablefish (Anoplopoma fimbria). We also focused on a key prey species, Walleye Pollock (Gadus chalcogrammus), and used environmental data collected during trawl surveys and PDO data generated for the entire North Pacific region. The first study completed was focused solely on the consumption of Walleye Pollock, a critical fishery species and ecosystem link. We used data from trawl surveys to determine the potential influence of local environmental variables on the predation rate of Walleye Pollock in the system by these groundfish. Using an information-theoretic approach, we found that predator length was positively related to Walleye Pollock presence and proportion of total diet weight in all predators. Increased temperatures positively affected consumption of Walleye Pollock by Pacific Halibut, but not the other predators. We found evidence for a number of inter-predator effects of co-occurring predators, both positive (facultative) and negative (competitive). Observed prey density was not statistically significant with respect to consumption for these predators, suggesting that trawls sample the environment differently than Walleye Pollock predators or species interactions are more complex than those used in previous multispecies models. In our second study, we considered the entire diet of these predators, rather than one key prey. Furthermore, because PDO had been described as leading to community changes in the system previously, we hypothesized that it could also be driving shifts in diets in the three groundfish predators we studied. We used a multivariate statistical approach to compare the diets of these predators by PDO state (warm or cold years) and also included local environmental covariates. Overall, we found that diets observed in PDO cold years were significantly different than diets in fish in warm years. In general, predators were found to be consuming more Walleye Pollock and euphausiids in warm years, and more benthic invertebrates and other forage fish in cold years. Local environmental covariates contributed to the diets observed in these predators, however no general pattern was observed. Our results also show the benefit of using diet data from large scale monitoring efforts as indicators of community shifts in a large marine ecosystem through time. Ultimately, we used our statistical analyses regarding diet and PDO state to drive a modeling exercise using alternate representations of the diets of the predators in the GOA. We investigated the potential impact of shifting diets in groundfish in an ecosystem-modeling framework, using Ecopath trophic-mass balance models. We changed the diets of key groundfish predators in the model based on our previous results for three alternative model parametrizations; 1) average conditions over the time period, 2) cold PDO state, and 3) warm PDO state. We noted a number of differences in model estimated ecosystem indices. Biomass accumulation estimates indicated that some ecologically and commercially important species groups would be expected to greatly diverge in population size if models were based on data from warm vs. cold PDO years compared to the averaged climatic state. In general, predator overlap was at its lowest in the cold year model, as predators had more diverse diets and therefore predation was more diffuse in the system in general. These results indicate the potential importance of environmental context when collecting diet data to be used in ecosystem models designed to provide fishery management recommendations. As ecosystem models are used more commonly, taking the time to investigate the factors that structure diets and how predation changes due to environment can yield more representative, and potentially more accurate biomass projections and recommendations for the GOA and likely many other managed marine ecosystems

Limiting Factors in Colonial Seabirds, with Emphasis on Predation, Disease, Parasites and Diet, and Implications for Monitoring Studies

Marine habitats have undergone dramatic changes, particularly over the last few decades. Human-related causes, such as habitat alteration, overexploitation, pollution, climate change and introduction of alien species have affected marine ecosystems worldwide, with severe impacts on many species, including several seabirds. Seabirds, and particularly (but not exclusively) those species that act as top-predators, are excellent monitors of the health of marine ecosystems. However, in order to make use of them as bioindicators, we have to understand how potential limiting factors influence their ecology. In turn, this information is also useful for the conservation of their populations. In this thesis I study a diversity of limiting factors of potential importance for the breeding ecology of two threatened seabirds, the southern rockhopper penguin and the black-browed albatross, at a mixed seabird colony on the Falkland Islands. An analysis of nesting habitat quality (Chapter 2) indicated that this did not explain variation in rockhopper penguin breeding success, which was most likely influenced by predation. An analysis of spatial and temporal variability of nesting success of black-browed albatrosses has shown that disease (Chapter 3), possibly coupled with parasites (Chapter 4) was the main cause for chick mortality differences between areas and years, whilst the consequences of a diet (Chapter 5) with a strong fisheries-related component for breeding success and chick development are still to be determined conclusively. This multi factor approach together with a relatively long-term set of data are important to produce more robust conclusions (with atypical years put into context), and to tentatively assign changes in breeding parameters to individual factors. My results help to provide a more complete insight of the potential factors threatening two species of conservation importance at this colony and in the context of the Falklands