Thesis advisor: John E. Ebel / The seismicity of the mid Atlantic Ridge (MAR) was compared in space and time with the seismicity along the Atlantic continental margins of Europe, Africa, North America, the Carribean and South America in a bid to appraise the level of influence of the ridge push force at the MAR on the Atlantic coastal seismicity. By analyzing the spatial and temporal patterns of many earthquakes (along with the patterns in their stress directions) in diverse places with similar tectonic settings, it is hoped that patterns that might be found indicate some of the average properties of the forces that are causing the earthquakes. The spatial analysis of the dataset set used shows that areas with higher seismic moment release along the north MAR spatially correlate with areas with relatively lower seismic moment release along the north Atlantic continental margins (ACM) and vice versa. This inverse spatial correlation observed between MAR seismicity and ACM seismicity might be due to the time (likely a long time) it takes stress changes from segments of the MAR currently experiencing high seismic activity to propagate to the associated passive margin areas presently experiencing relatively low seismic activity. Furthermore, the number of Atlantic basin and Atlantic coast earthquakes occurring away from the MAR is observed to be independent of the proximity of earthquake’s epicenters from the MAR axis. The effect of local stress as noted by Wysession et al. (1995) might have contributed to the independence of Atlantic basin and Atlantic coast earthquake proximity from the MAR. The Latchman (2011) observation of strong earthquakes on a specific section of the MAR being followed by earthquakes on Trinidad and Tobago was tested on other areas of the MAR and ACM. It was found that that the temporal delay observed by Latchman does not exist for the seismicity along other areas along the MAR and ACM. Within the time window used for this study, it appears that seismicity is occurring randomly in space away from the MAR. The weak anticorrelations between ACM and MAR seismicity show that the ridge push force probably has some level of influence on the ACM seismicity. However, as revealed from previous research on the study area, the forces resulting from lateral density contrasts related to topographic features and lateral density variations between oceanic and continental crust also appear to significantly influence the seismicity of the Atlantic coastal margins. / Thesis (MS) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

The type of Atlantic salmon immune response to amoebic gill disease was investigated by analysis of cytokine genes possibly related to the TH1, TH17 and Treg pathways, which were significantly down regulated, while il-4/13 isoforms, possibly related to the TH2 pathway, were found to be significantly up regulated. Moreover, the injection of Atlantic salmon with rIfn-γ, which might initiate the TH1 immune pathway, did not reduce infection load of Paramoeba perurans or severity of gill pathology in challenged fish. Different arginase isoforms present in salmonids were also characterised and the data supported the concept that arginase type II may be a more relevant marker of alterantive activate macrophages in teleost fish induced by rIl-4/13. Regarding the biology of P. perurans, the susceptibility of amoebae to different environmental conditions showed that amoebae exposed to salinities lower than 3 ppt were disrupted or did not recover after 16 days, while all amoebae cultures showed a significant difference between the two temperatures (10°C and 15°C) studied over time. Significant differences were also found in relative abundance of the 30 most prevalent bacterial genera present in the isolated P. perurans cultures (16S rRNA). The impact of stress on the host response to AGD was tested for the presence of an association between temperature (10°C and 15°C) and variation in severity of AGD in Atlantic salmon. This association was demonstrated for the histopathology and P. perurans load analysis, reflecting an earlier and stronger AGD infection at the higher temperature (15°C) treatment. No significant difference between the two temperature treatments was shown in hormonal and molecular responses. Therefore, temperature might not act as a chronic stressor but its effect could be linked to the higher amoebae attachment seen at higher temperatures in the in vitro experiment reported.

This thesis explores the British government’s approach to international negotiations concerning nuclear weapons during Harold Wilson’s first two terms of office (1964-1970). It focuses on three distinct but interrelated strands of British nuclear diplomacy: ‘hardware solutions’, the sharing of nuclear weapons between states in the form of a multilateral force; ‘software solutions’, non-physical measures of cooperation, such as consultative and planning arrangements, between alliance members; and a global non-proliferation treaty. In looking at how and why these interrelated policies evolved, this thesis considers party, domestic and international influences on decision-making within the government. It pays particular attention to political and economic events, building on existing diplomatic and strategic accounts of the period.

The last two glacial terminations represent the most recent, and best documented, periods of Earth warming in the geological record. During these terminations atmospheric CO\textsubscript{2 }rose by approximately 100 ppm and global mean temperatures increased by 4-6\textsuperscript{o}C. Whilst the driver for these deglaciations ultimately derives from changes in the insolation forcing at the edge of the atmosphere, feedbacks within the Earth\textquoteright s climate system act to amplify these small external forcings tipping the Earth from a cold glacial climate state to a warm interglacial climate state. A key question in Quaternary climate science is understanding which feedbacks are important in regulating global climate on glacial-interglacial timescales. On this topic, the Southern Ocean has long been considered to be an important player in regulating atmospheric CO\textsubscript{2 } on glacial-interglacial timescales. This thesis investigates some of the hypothesised drivers of changes in atmospheric CO\textsubscript{2 } on glacial-interglacial timescales by generating high-resolution multi-proxy records from the Southern Ocean spanning the last two glacial terminations. In particular, I focus on changes in the structure, circulation and biological productivity within the sub-Antarctic zone. A change in the deep ocean density structure has been hypothesised to have resulted in the release of CO\textsubscript{2 } from the deep ocean. Centennial records from the sub-Antarctic are used to reconstruct deep and intermediate water density for the first time. I demonstrate that timing of the major breakdown in the density gradient of the ocean significantly lagged the breakdown in the chemical gradient, suggesting that changes in the deep ocean density structure were not the major driver of the deglacial rise in atmospheric CO\textsubscript{2 }. Changes in the density structure of the Southern Ocean likely had significant implications for global circulation. In particular, the flow of low salinity water through the Drake Passage is thought to be important in setting the strength and geometry of Atlantic Overturning Circulation. Drake Passage through-flow speed was reconstructed from two sites in the central and northern margins of the Antarctic Circumpolar Current downstream of Drake Passage. These records suggest a very different structure of Antarctic Circumpolar flow through Drake Passage during glacial periods, and evidence significant changes in ocean temperature as a result of pronounced reductions in Drake Passage through-flow. The strength of the biological pump has long been identified as an important player in regulating atmospheric CO\textsubscript{2 }. In particular, a strong glacial increase in sub-Antarctic productivity has been observed at open ocean sites in the South Atlantic and Indian Ocean. However, the glacial-interglacial changes in productivity in sub-Antarctic shelf settings are less well-documented. The new high-resolution records presented here from the sub-Antarctic southwest Atlantic suggest a significant change in the CaCO\textsubscript{3}:C\textsubscript{org} ratio which likely has implications for the surface ocean\textquoteright s ability to uptake CO\textsubscript{2 }.

Overfishing in the Benguela Current Large Marine Ecosystem (BCLME) resulted in degradation of the ecosystem. This study used the Driver-Pressure-State-Impact-Response (DPSIR) indicator framework to determine whether the ecosystem is now recovering. Indicator trends were analysed using various data sources that included government institutions and intergovernmental institutions. The results showed that the overall effect of Driver indicators was negative. This was mainly because of socio-economic pressure such as the need to create more jobs in light of rising national unemployment and the declining contribution of the fisheries sector to Gross Domestic Product (GDP). In addition to scientific advice, socio-economic factors also influenced the determination of Total Allowable Catches (TACs). The overall trend of Pressure indicators was positively influenced by the effect of TACs. The TACs reduced the quotas allocated for commercial fishing. Environmental factors did not seem to play a significant role in this study. State indicators had mixed results with the indicators assessed almost split in the middle between those showing a positive trend and those showing a negative trend. On the other hand, Impact and Response indicators showed overall positive results. Therefore, the conclusion of the study was that the degradation of the BCLME has slowed down and there are some signs of recovery. / Environmental Sciences / M.Sc. (Environmental Science)

No description available.

In this thesis, we improved our understanding of the effects of hydrology, stream hydraulics, and temperature on juvenile Atlantic salmon (Salmo salar L.) habitat. We demonstrated the key role played by stream morphology and flow regime on in-channel hydraulics and consequently on salmonid habitat. Additionally, we showed how riparian afforestation has potential to moderate climate change effects on stream temperature preserving freshwater ecosystems. The Girnock Burn is an upland Scottish river that has been intensively studied to investigate flow generation processes and stream temperature, and has served as a long-term monitoring site for Atlantic salmon population dynamics since 1966. The general approach applied consisted of combining different types of models including: hydraulic, fish habitat, hydrological and heat transfer models with long-term hydrological and climatic data sets, and digital terrain models (DTMs) at different spatio-temporal scales. Our results showed that the extensive presence of roughness elements (e.g. boulders and cobbles) is capable to provide some refuge areas for juvenile salmon fry for a wide range of flows. However, under extreme flow conditions, in-channel hydraulics might represent a limiting factor. Significant inter-site differences occurred and were consistent throughout the years. Evidence of long-term trend in fry habitat quality could be identified only in summer. Since more extreme flow regimes are expected in the future as a result of climate change, we also proposed a novel analytical approach that allowed us to assess the effects of hydroclimatic variation on fish populations outside the range of observations. Finally, we showed the potential of afforestation to reduce daily stream temperature range, moderating both low and high peaks of more than 2 ○C. This makes riparian shading a valuable mitigation strategy to contrast global warming effects on stream temperatures that should be considered for a sustainable catchment management.

Orientador: Edilberto Giannotti / Banca: Fábio Prezoto / Banca: Maria José de Oliveira Campos / Resumo: A Mata Atlântica é um ecossistema muito relevante para a biologia da conservação e possui uma das maiores diversidades de espécies do continente, inclusive a de vespas sociais. Este grupo de insetos, que no Brasil está representado pelos Polistinae, causa grandes impactos nos ecossistemas, já que as vespas são importantes predadoras e coletoras de néctar. Tendo em vista que o inventário das espécies de uma área é o ponto inicial para a sua preservação, o objetivo do estudo foi efetuar um levantamento da diversidade de vespas sociais da Mata Atlântica da Serra do Mar do litoral norte do estado de São Paulo, enfatizando a importância desse grupo para avaliações de impacto ambiental e de efeitos de fragmentação florestal da região. Além disso, foi possível comparar a eficiência das metodologias utilizadas, verificando se ocorre preferência das vespas pelo conteúdo das armadilhas. As coletas foram realizadas na Fazenda Angelim Rainforest de maio de 2007 a maio de 2008, utilizando armadilhas atrativas de garrafa PET e coleta ativa. Foram encontradas 21 espécies pertencentes a oito gêneros e, dentre elas, algumas são raras na região sudeste do país, como Mischocyttarus parallelogrammus e Polybia catillifex. As espécies mais freqüentes foram Agelaia angulata (64,31%), A. sp. prox. centralis (10,08%) e Angiopolybia pallens (8,49%). Observou-se correlação entre a riqueza das espécies e a umidade relativa do ar. Analisando os distintos ambientes, verificou-se maior riqueza, abundância e índice de diversidade de Margalef na área antropizada (A=793, R=14, DMg=4,4839, H'=1,08), mas a maior diversidade obtida pelo índice de Shannon-Wiener foi na área de mata fechada (A=174, R=8, DMg=3,1242, H'=1,17). As armadilhas com atrativo glucídico obtiveram maior riqueza, igual a 16 espécies ou 76,19% da riqueza total coletada. As armadilhas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Atlantic Rain Forest is very relevant for conservation biology and has one of the greatest biodiversity in the continent, including social wasps diversity. This group of insects, which in Brazil is represented by Polistinae, causes major impacts on ecosystems, because the wasps are important predators and collectors of nectar. Bearing in mind that the inventory of species in an area is the starting point for its preservation, the goal of this study was to perform a survey of the social wasps diversity of the Atlantic Forest on the north coast of São Paulo State, emphasizing the importance of this group for environmental impact assessments and the effects of forest fragmentation in the region. Furthermore, it was possible to compare the efficiency of the methodologies, verifying if there is a preference of the wasps for the contents of the traps. The collections were made in Fazenda Angelim Rainforest from May 2007 to May 2008, using attractive PET bottles traps and active searching. We found 21 species belonging to eight genera and among them; some are rare in the southeast region of the country, such as Mischocyttarus parallelogrammus and Polybia catillifex. The most frequent species were Agelaia angulata (64.31%), A. sp. prox. centralis (10.08%) and Angiopolybia pallens (8.49%). Correlation was observed between species richness and relative air humidity. When analyzing the different environments, it was possible to verify a greater richness, abundance and Margalef diversity index in the anthropic area (A= 793, R= 14, DMg= 4.4839, H= 1.08), but the greatest diversity obtained by Shannon-Wiener index was in the area of dense vegetation (A= 174, R= 8, DMg= 3.1242, H'= 1.17). The traps with glucidic attractive obtained greater richness, equal to 16 species or 76.19% of total richness collected. Traps with protein content were the least effective (six species, 28.57% of total richness)... (Complete abstract click electronic access below) / Mestre

A multi-disciplinary study of sediment core records from the Mingulay Reef Complex, a cold-water coral reefs system off western Scotland, highlights the potential of cold-water corals from which detailed centennial-scale palaeo-environmental reconstructions can be derived. This study provides a new insight on the mechanisms controlling Lophelia pertusa reef build-up, shifts in biodiversity, the physical/chemical/biological processes and the sedimentary regime. A detailed record of Mingulay Complex growth history shows unprecedented high average accumulation rates of 3 – 4 mm a-1. Marine radiocarbon reconstruction derived from paired 14C and U-series dated fossil corals revealed substantial abrupt oceanic shifts during the Holocene that have repetitively affected cold-water coral growth, eventually causing local disappearance. These periods of reduced accumulation rates are synchronous with other coral structures from the NE Atlantic illustrating basin wide events. Finally, trace/minor element ratios reproducibility within coral skeleton was investigated to test if palaeo-environmental reconstructions could be made from cold-water corals.

Brazil is the world's sixth largest cocoa producer with 270,000 tonnes of cocoa produced per year. In a world with an increasing demand for chocolate, but with agriculture threatened by climate change, the chocolate industry is worried about a possible shortage of cocoa. Furthermore, growing cocoa is a main cause of deforestation. However, in the state of Bahia, Northeast Brazil, cocoa is grown in traditional agroforests called 'cabrucas' which maintain a forest cover. Cocoa, an understorey crop, is planted under the shade of native Atlantic Forest trees and exotic fruit trees introduced by the farmers. These cabrucas have high conservation value but very low cocoa yield. In my thesis I investigate the factors limiting cocoa yield and how to increase yield in cabrucas. I explore the role of shade trees and the nutrient dynamics in litterfall. Finally, I explore the risk that climate change could represent for cocoa production in the future by looking at the effects of an unexpected drought caused by an El Niño Southern Oscillation (ENSO) event between November 2015 and May 2016. My study is based on data collected in permanent transects in 32 randomly chosen cabruca farms in Barro Preto a municipality of Bahia over a period of three years. I also established littertraps in 10 cocoa farms where I intensively studied nutrient dynamics and cocoa yield per tree over 12 months. My results showed that unproductive trees, low cocoa tree density, high shade cover and high cocoa mortality due to drought were the main factors limiting cocoa yield in cabrucas. Surprisingly, adding fertilisers to the cocoa trees did not increase yield. This suggests that there is no nutrient deficiency in cabrucas. In the farms, I found 69 species of shade trees for an average density of 125 ± 32 trees per hectare. Half of the species of shade trees were Atlantic Forest species of conservation value. The litterfall experiment showed the shade tree species and the quantity of litterfall produced, can affect the number of cocoa pods per tree. In cabrucas, a higher number of cocoa pods was found on cocoa trees under shade trees than under no shade. Finally, I showed that the exceptionally severe ENSO-related drought caused 80% loss in yield and 11% cocoa tree mortality in Barro Preto. Climate models predict an increased frequency of strong ENSO events in the future. Farmers in Bahia are not prepared to face regular drought events. The 2015/16 drought affected the dynamics of cocoa production in Brazil: it accelerated the decrease of extensive wildlife-friendly cocoa production in Bahia whereas it increased the development of cocoa production in intensive low shade plantations in the state of Pará. This suggests that climate change could be a threat to traditional cocoa agroforests in Bahia. Developing wildlife-friendly certification schemes and Payment for Ecosystem Services to internalise the value of forest conservation and to encourage farmers to maintain their shade trees could save cabruca systems from going extinct.