Rozprawy doktorskie na temat „Antarctic”

The distribution, abundance, chemical composition, metabolism, and feeding ecology of the tentaculate ctenophore, Callianira antarctica (Chun 1897), were investigated during austral winter 2001and autumn & winter 2002, in the vicinity of Marguerite Bay west of the Antarctic Peninsula. Callianira antarctica had a widespread distribution during autumn and winter, and variable abundance (0.02 to 2.6 ind. m-2) during winter 2001 associated with specific circulation features. Size frequency distributions for autumn and winter suggest that more than half of the C. antarctica population may have experienced 'degrowth' during winter due to low food availability. Callianira antarctica is a fairly robust ctenophore with geometric mean (geomean) carbon (C) and nitrogen (N) values of 8.41 and 1.83% dry weight (DW), respectively. Winter oxygen consumption and ammonium excretion rates ranged from 0.059 to 0.410 micro l O2 [mg DW]-1 h-1 and 0.60 to 31.1 µg-at N [g DW]-1 h-1, respectively, at 0oC. Daily minimum maintenance rations based on respiration experiments were 2.7% to 3.6% of the total body carbon (TBC) for small ctenophores, and 1.4% to 1.9% TBC for larger ctenophores. Calanoid copepods and larval and juvenile Antarctic krill were offered to ctenophores in incubation experiments. Digestion times were variable, lasting 8 to 20 h, and were independent of ctenophore size and dependent on number and type of prey. Gut content analysis from one autumn and two winter seasons indicated C. antarctica preyed on both copepods and krill in situ, with an increased dependence on larval krill during winter. Lipid biomarker analysis on C. antarctica and their potential prey confirmed these results. Divers observed aggregations of C. antarctica passively drifting with tentacles extended near dense concentrations of larval Euphausia superba during winter. These observations along with gut content and lipid biomarker analysis suggest that larval krill is an important prey item for C. antarctica during winter.

The thesis analyses the expedition (TAE) led by Dr.Vivian Fuchs and Sir Edmund Hillary from three vantage points: 1)the years from 1948 to 1955 leading up to the expedition 2) the interaction between the IGY and the TAE projects and 3) the role of the US Navy as the expedition unfolded. The thesis also investigates key events including the purchase of the ship Endeavour from Britain, the competition for leadership of the UK and NZ parties, the 'dash to the Pole' by Hillary, and the search for base sites and routes to the Polar Plateau. The thesis contains an overview historical introduction, a comprehensive literature review as well as a broad-based set of conclusions.

In light of growing international awareness and interests in the ‘frozen continent’ of Antarctica, the topic of Values in Antarctica has recently gained more research interest. Due to the complexity of the concept of value, values in Antarctica have been approached from many different perspectives, including Antarctic wilderness and aesthetic values, values manifested in Antarctic law or value based behavioural changes through the Antarctic experience. The present thesis addresses values as human connections to Antarctica with a focus on Antarctic policy-making. The investigation contained three analytical stages that built on each other. The first stage has been an interdisciplinary literature review examining what values are and how values can be studied, but also considered values in the context of environment, human behaviour and policy. Value and value-related concepts were selected in view of a potential application to the Antarctic. The second analytical stage involved a general framework analysis of the Antarctic Treaty System to identify key elements and structures in the system suitable for a study of Antarctic values, and to develop the research questions. The third stage of analysis included empirical investigations of two Antarctic case studies. Key elements that influence the Antarctic Treaty System in a way that is relevant for a study of Antarctic values include external factors and events, action situations and actors participating in these action situations. Antarctic Treaty Meeting of Experts appeared as an action situation particularly suitable for a study of Antarctic values. The last two Antarctic Treaty Meeting of Experts on ship-borne tourism and climate change have been chosen as case studies, presenting two topical issues in Antarctic policy. Using discourse analysis based on documents submitted to the meetings and the meetings’ reports, values that are driving the discourses were to be identified through structures and patterns in the discourses. Further, based on the discourse analysis following three research questions were to be answered: What role is ascribed to Antarctica concerning contemporary issues? Where and why do conflicts arise in the ATS policy-making process that are based on conflicting values? What changes in the underlying belief-systems are driving policy-making processes and what has caused the change? Based on the literature, values are defined as internalised codes that affect behaviour and include judgements on what is good and desirable. Through the framework analysis it was identified that Antarctic policy involves a multi-layered system of different value systems, which was considered in the two case studies. For both case studies, values in the discourses were mostly identified based on Schwartz’s basic human value theory. The most prominent human value that drives both the ship-born tourism and the climate change discourse is security. Both discourses are further motivated by the conservation of the Antarctic environment and its associated ecosystems. Other values, such as power and conformity with rules were also clearly expressed in the discourses. With regard to the research questions, both case studies discussed Antarctica from two different perspectives, as a hazardous place for human activities and as a place vulnerable to any kind of changes. Conflicts in the ship-borne tourism discourse were more obvious, while the climate change discourse within the expert meeting proceeded in consensus. Value-based changes that are evident in changes in belief-systems underlying Antarctic policy-making could not be identified. This thesis argues, based on careful consideration of documents, that values play a crucial role in Antarctic policy-making at a number of different scales: individuals, political actors, and governmental levels. Values were found to be at the core of most, if not all, conflicts within the Antarctic system. Finally, this thesis provides the first understanding of the values held by the various stakeholders involved in governing and use of the Antarctic, which is crucial for further decision-making and research.

The Antarctic silverfish (Pleuragramma antarctica) is a keystone species in the continental shelf waters around the Antarctic, performing an essential role of connecting higher and lower trophic levels in the Southern Ocean ecosystem. Its early life history is dependent on the platelet ice layer found below sea ice, thus intimately intertwining its fate with that of sea ice extent. Antarctic silverfish belong to the family Nototheniidae, part of the Notothenioidei suborder whose species radiation in the Southern Ocean 24 million years ago is one of the most expansive among teleost fish. Most notothenioids inhabit a benthic niche as adults, though many experience a pelagic egg and larval phase. Antarctic silverfish are unique among notothenioids in that they are pelagic throughout their life history. Larvae develop in the platelet ice layer near the surface beneath sea ice, descending into deeper waters as they grow in size as juveniles, finally reaching their maximum depth range as adults at 400 – 700 m below the surface. While they lack a swim bladder, Antarctic silverfish manage to remain in the water column as adults by a type of paedomorphy in which they retain lipids from larval and juvenile life stages, allowing them to achieve neutral buoyancy. Despite their presence in the water column as adults, they practice a similar energy-efficient life strategy to their benthic counterparts. Their feeding strategy involves hanging in the water column and passively consuming prey. Remaining in the water column throughout their life history combined with their passive life strategy renders Antarctic silverfish especially susceptible to transport via local and circumpolar current systems. Thus, local and circumpolar current systems form the hydrographic framework in which hypotheses regarding Antarctic silverfish population connectivity must be tested. How populations of fish are defined, and the extent to which separate populations exchange individuals forms the basis of marine fish population biology. The extent to which Antarctic silverfish, which have a circumpolar distribution, represent one fully connected, panmictic population around the Antarctic continent, remains an open question. It is reasonable to presume that, given their pelagic larval phase, many species of notothenioids with a circumpolar distribution represent large, homogeneous populations. This presumption remains the null hypothesis to test when investigating population structure in notothenioids, and it is especially salient when considering the fully pelagic Antarctic silverfish. The first investigation into Antarctic silverfish population structure employed mitochondrial DNA markers on a circumpolar scale and did not find evidence to reject the null hypothesis of panmixia throughout the Southern Ocean. Intriguingly, while comparisons between regions failed to indicate differentiation, comparisons within regions between years hinted at inter-annual variation in patterns of connectivity. Genetic differentiation within the same geographic area that is lost and gained between sampling years due to variations in recruitment, mortality and hydrography is known as chaotic genetic patchiness. The extent to which chaotic genetic patchiness is relevant to understanding Antarctic silverfish population structure was further studied in a more recent investigation, restricting its geographic focus to the Antarctic Peninsula, and employing a set of highly polymorphic EST-linked microsatellite markers to understand population connectivity around the Antarctic Peninsula. Based on both its more focused regional scale and sampling scheme, as well as the use of genetic markers more adept at capturing population differentiation, this study was able to detect genetic structuring on the scale of the Antarctic Peninsula. Building upon these initial studies, this thesis aimed to characterize the circumpolar population structure of Antarctic silverfish, integrating aspects of life history and hydrography in order to describe mechanisms of connectivity between populations. The first aim was to understand the hydrography underlying life history connectivity on the scale of the Ross Sea region in order to better understand what may be occurring on the circumpolar level. Silverfish larvae were collected from areas in the Ross Sea coincident with hydrographic features hypothesized to influence their connectivity. While a microsatellite-based analysis was precluded due to the poor state of preservation of the larvae, it was possible to confirm species identification using mitochondrial sequence analysis. The genetic confirmation of species was especially important given that this study proposed a new spawning ground for silverfish in the Ross Sea based on size at collection and established growth rates from the time of hatching. Importantly, this study provided renewed support for the life history hypothesis in silverfish, emphasizing the impact of trough circulation in transporting early life stage fish from the ice shelf edge to the continental slope, where retention back towards the coast or entrainment in shelf-long currents modulates connectivity between neighboring populations of silverfish. The Ross Sea investigation was then expanded on a circumpolar scale, now carried out using a suite of highly polymorphic EST-linked microsatellite markers developed in a closely related notothenioid species and shown to successfully amplify in silverfish in a previous study. This analysis was carried out on fish collected over 25 years from six different regions: the western Ross Sea, the eastern Weddell Sea, Larsen Bay, the northern Antarctic Peninsula, the South Orkney Islands, and the western Antarctic Peninsula. The data analyzed included samples from the two previous investigations of silverfish population structure described earlier, the first using mitochondrial markers on a circumpolar scale that had not found evidence of population structuring, and the second using the same suite of microsatellite markers employed in this thesis on a regional scale around the Antarctic Peninsula. The integration of these previous datasets into the present analysis allowed for an increase in the resolving power of the previous mitochondrial marker-based study, as well as for the integration of the Antarctic Peninsular work into the greater circumpolar context. The circumpolar investigation of Antarctic silverfish population structure confirmed that the population structure of silverfish on a circumpolar scale is characterized by high levels of gene flow, and suggested that the Antarctic Slope Front and Current System (AFS) plays an integral role in connecting populations in the Southern Ocean. The importance of the AFS was evident in that reductions in gene flow were only observed in the South Orkney Islands and west Antarctic Peninsula, which were the only two areas in the study where the AFS has not been shown to arrive. This result also expanded to a circumpolar scale the earlier Ross Sea study, which had emphasized the importance of the AFS in connecting Ross Sea populations between local trough systems. It remained however, that small scale population differentiation which had been observed in the Ross Sea based on larval distributions, as well as in the eastern Weddell Sea based on the distribution of older and younger cohorts between sampling areas, was unable to be resolved using genetic techniques. Thus, the final aim of the main project of this thesis was carried out in order to resolve population structure on the regional scale, this time in the Weddell Sea, employing otolith chemistry. Analysis of trace element deposition in otolith nuclei, reflective of oceanographic conditions to which fish were exposed in early life, has been shown to delineate population structure in the Southern Ocean, in both silverfish and related notothenioids. Of the stations for which samples were available in the Weddell Sea, five stations were selected based on their locations with respect to hydrographic features hypothesized to influence population structuring in the region, in Atka Bay, Halley Bay, off of Coats Land, and west and east of the Filchner Trough. Previous studies, as well as data on biomass and abundance from the sampling expedition during which the silverfish were collected, emphasized the importance of the Filchner Trough in supporting a local population of silverfish in the eastern Weddell Sea continental shelf area. Furthermore, hydrographic data collected in the Weddell Sea emphasized the importance of warm water mass intrusion onto the continental shelf carried from the east into the Weddell Sea region by the AFS. These warm water intrusions from the AFS not only have the potential to carry fish from other regions into the Weddell Sea area, but regulate circulation patterns and the strength and directionality of coastal currents in the region, modulating local connectivity. The results of the otolith nucleus chemistry analysis revealed significant population structuring along the eastern Weddell Sea, in contrast to the structure revealed using genetics. The population structure revealed by the otolith chemistry analysis supported the importance of warm water intrusions from the AFS in transporting fish between areas, while highlighting the role of the Filchner Trough circulation in supporting a coherent population in the southeast Weddell Sea. These results emphasize the importance of the integration of multidisciplinary techniques in the context of local hydrography in addressing questions of population structure and life history connectivity in Antarctic silverfish in the Southern Ocean, and for that matter, any pelagic species inhabiting a continental shelf ecosystem.
L’antarctic silverfish (Pleuragramma antarctica) è una specie chiave nelle acque della piattaforma continentale antartica, dove svolge un ruolo essenziale nel collegare i diversi livelli trofici. La sua life history dipende, nella prima fase, dal cosiddetto “ghiaccio a placchette” (platelet ice), che si forma all’interfaccia tra l’acqua marina e lo strato di ghiaccio superficiale, legando strettamente il destino di questa specie all’estensione del ghiaccio antartico. L’antarctic silverfish appartiene alla famiglia Nototheniidae, che fa parte del sottordine dei Nototenioidei, la cui radiazione, avvenuta nell’oceano Antartico a partire da 24 milioni di anni fa, rappresenta una delle più spettacolari radiazioni adattative nei pesci teleostei. I nototenioidei comprendono, nella maggior parte dei casi, specie demersali in fase adulta, ma caratterizzate da uova e larve pelagiche; l’antarctic silverfish è unico sotto questo punto di vista perché è pelagico durante tutto il ciclo vitale. Le larve si sviluppano nello strato di platelet ice sotto il ghiaccio marino superficiale e scendono verso acque più profonde durante la maturazione, arrivando come adulti a profondità massime di 400 – 700 m. Nonostante l’assenza di vescica natatoria, l’antarctic silverfish riesce a mantenersi nella colonna d’acqua nello stadio adulto grazie a un tipo di pedomorfia caratterizzato dal mantenimento e dall’aumento dei lipidi presenti nelle fasi larvali e giovanili, che ne aumenta il potere di galleggiamento. Malgrado l’habitus pelagico da adulto, il silverfish è molto efficiente dal punto di vista energetico, possedendo una strategia alimentare simile alle controparti bentoniche, che consiste in questo caso nel galleggiare passivamente nella colonna d’acqua, consumando le prede che capitano nei paraggi, ma senza investire energia in una vera e propria ricerca attiva delle prede. Il fatto di rimanere nella colonna d’acqua durante tutto il ciclo vitale, in combinazione con la strategia di vita passiva, rende l’antarctic silverfish particolarmente suscettibile al trasporto da parte dei sistemi di correnti locali e circumpolari. Questo aspetto lo rende particolarmente interessante nel contesto della biologia di popolazione dei pesci marini, dove risulta importante identificare la presenza di diverse popolazioni e definire l’entità con cui popolazioni separate scambiano individui. In particolare, il fatto che l’antarctic silverfish, che ha una distribuzione circumpolare, presenti o meno una singola popolazione panmittica attorno al continente antartico, rimane una questione aperta. Dato che le fasi larvali sono pelagiche, è ragionevole presupporre che molte specie di nototenioidei siano organizzate in grandi popolazioni omogenee su scala geografica più o meno ampia. Questo presupposto fornisce l’ipotesi nulla da testare quando si investiga la struttura di popolazione di questo gruppo, ed è specialmente rilevante se si considera l’habitus pelagico dell’antarctic silverfish. Il primo studio della struttura genetica di popolazione dell’antarctic silverfish è stato svolto con marcatori del DNA mitocondriale; questa indagine, svolta su una scala circumpolare, non ha fornito evidenze tali da confutare l’ipotesi nulla di panmissia per l’intero oceano antartico. Tuttavia, mentre i confronti svolti tra diverse regioni non sono riusciti a dimostrare la presenza di differenziamento genetico, i confronti svolti entro regioni tra diversi anni di campionamento hanno suggerito l’esistenza di variazione inter-annuale del grado di connettività. Il differenziamento genetico tra anni di campionamento entro la stessa area geografica è riconducibile al fenomeno della chaotic genetic patchiness e può essere dovuto a variazioni nel tasso di reclutamento e mortalità e nell’idrografia. La presenza di differenziamento genetico di popolazione e di chaotic genetic patchiness nell’antarctic silverfish sono stati recentemente confermati mediante genotipizzazione di microsatelliti EST-linked in uno studio focalizzato su campioni provenienti dalla Penisola Antartica. In questo caso, l’utilizzo di marcatori genetici ipervariabili caratterizzati da un elevato potere risolutivo ha permesso di rilevare una significativa struttura genetica sulla scala regionale della Penisola Antartica. Questa tesi di dottorato mira a caratterizzare la struttura di popolazione circumpolare dell’antarctic silverfish, integrando l’informazione fornita dagli studi iniziali con nuovi campioni ed interpretando i risultati alla luce dei diversi aspetti di life history ed idrografia al fine di descrivere i meccanismi di connettività tra popolazioni. Nel primo studio prodotto nell’ambito di questa tesi di dottorato, sono stati analizzati dei campioni di larve dell’antarctic silverfish provenienti dal Mare di Ross, con l’obiettivo di legare l’idrografia locale alla connettività della specie. Lo stato di conservazione dei campioni non ha permesso di utilizzare marcatori molecolari nucleari (microsatelliti) per studiare il differenziamento tra siti geografici entro il Mare di Ross. Nonostante questo, è stato possibile sequenziare un frammento di DNA mitocondriale che ha permesso di identificare univocamente le larve come apparteneneti alla specie P. antarctica. Questo risultato è particolarmente rilevante perché conferma, grazie all’utilizzo di metodi genetici, la presenza di larve della specie P. antarctica in alcune aree del Mare di Ross che erano state precedentemente solo ipotizzate essere zone preferenziali di nursery del silverfish, sulla base di tempi di raccolta dal momento della schiusa delle uova e del tasso di crescita ipotizzato. Sulla base dell’idrografia locale, questo studio ipotizza che la circolazione legata alle depressioni del fondale sia essenziale per il trasporto delle fasi di vita iniziali dalle zone più costiere fino alla scarpata continentale, mentre l’idrografia costiera potrebbe controllare il trasporto lungo i margini della piattaforma continentale modulando la connettività tra popolazioni adiacenti. In un secondo studio prodotto nell’ambito di questa tesi di dottorato sono stati analizzati campioni raccolti nell’arco di 25 anni da sei regioni antartiche diverse: la parte ovest del Mare di Ross, la parte est del Mare di Weddell, la Baia di Larsen, la parte nord della Penisola Antartica, le Isole di South Orkney, e la parte ovest della Penisola Antartica. Questo studio su scala circumpolare è stato condotto utilizzando un pannello di 18 loci microsatellite isolati in precedenza per varie specie di nototenioidei antartici. Questi loci sono risultati polimorfici anche in P. antarctica e informativi per gli obiettivi di questa tesi di dottorato. Alcuni dei campioni inclusi in questo studio sono stati analizzati in due studi precedenti: un primo studio non aveva evidenziato segnali di differenziamento genetico a livello circumpolare (analisi di un marcatore mitocondriale) mentre un secondo studio, più recente e focalizzato sulla Penisola Antartica, aveva segnalato chaotic genetic patchiness e differenziamento genetico utilizzando lo stesso pannello di 18 microsatelliti genotipizzati in questa tesi di dottorato. Questo secondo studio ha confermato che la struttura di popolazione del silverfish sulla scala circumpolare è caratterizzato da alti livelli di flusso genico suggerendo che il sistema di correnti, in particolare l’Antarctic Slope Front and Current System (AFS), abbia un ruolo critico nel collegamento delle popolazioni nell’oceano Antartico. L’importanza del AFS è suggerita dal limitato flusso genico tra le aree ad ovest della Penisola Antartica e le South Orkneys, le due uniche zone non raggiunte dall’AFS. Questa considerazione è ulteriormente supportata dall’ipotesi che l’AFS mantenga la connettività tra depressioni del fondale anche nel Mare di Ross. Per comprendere se l’assenza di differenziamento nell’area ad est del Mare di Weddell fosse effettivamente un fatto biologico o fosse dovuta alla scarsa sensibilità dei marcatori microsatellite a piccole differenze, è stato condotto un ulteriore studio utilizzando l’analisi della chimica degli otoliti di silverfish. La quantificazione delle tracce di elementi deposti nel centro (nucleus) degli otoliti è indicativa delle condizioni chimiche oceanografiche alle quali gli individui sono stati esposti nelle fasi iniziali dello sviluppo. Questa metodologia permette di conseguenza di testare se gli individui siano stati esposti a masse d’acqua diverse nelle prime fasi di vita e di dimostrare l’esistenza di popolazioni con diversa origine. Tra i campioni disponibili per il Mare di Weddell, sono state scelte 5 aree sulla base degli aspetti idrografici che potrebbero influire sulla struttura di popolazione locale (Baia di Atka, Baia di Halley, vicino alla costa di Coats, ad est ed ovest del Filchner Trough). Dati di abbondanza e biomassa raccolti in parallelo durante in campionamento del silverfish nel Mare di Weddell avevano già evidenziato l’importanza del Filchner Trough nel sostenere la popolazione locale dell’antarctic silverfish. Inoltre, l’idrografia locale, attraverso l’intrusione di acqua più calda dall’AFS verso il Mare di Weddell, permetterebbe sia di trasportare il silverfish verso il Mare di Weddell sia di regolare direzionalità e tasso di connettività locale. In contrasto con quanto evidenziato dall’approccio genetico, le analisi di microchimica degli otoliti segnalano differenze statisticamente significative tra gruppi di individui all’interno del mare di Weddell, in particolare tra nordest e sudest del Mare di Weddell. Questi studi suggeriscono un ruolo chiave dell’idrografia sia su scala circumpolare che locale nel modulare la connettività delle popolazioni dell’antarctic silverfish. Inoltre, questa tesi di dottorato evidenzia come un approccio multidisciplinare possa chiarire questioni di connettività di popolazione proponendo una metodologia applicabile a diversi organismi sia antartici che non.

The Eastern Antarctic Dry Valley region is a polar desert, where conditions of extreme aridity, high temperature fluctuations and high irradiation levels make it one of the most extreme environments on earth. Despite the harsh environment, the soils in this region yield a wide range of bacterial and eukaryotic phylotypes in greater abundance than previously believed. In the Dry Valleys, highly localized niche communities colonise the underside of translucent quartz rocks and present macroscopic growth.

Connections between South Africa and Antarctica can be traced as far back as the 1700s when European expeditions in search of the southern continent used Cape Town (and later Simonstown) as a base of operation. This link expanded considerably after formal British acquisition of the Cape of Good Hope in 1815, yet it was not until 1926 that an actual South African policy towards the Antarctic began to materialize. Once this policy was established it continued to be characterized by procrastination as well as resistance both from within and without South Africa. The history of South Africa's Antarctic policy can be divided into five periods: first, the commencement of the policy (focusing primarily on economic interests), 1926-1939; second, the pursuit of interests through the policy (focusing on political interests), 1944- 1958; third, the entrenchment of South Africa's interests in the Antarctic (by securing South Africa's position within the Antarctic Treaty System), 1958-1960; fourth, the expansion of and foreign assault on the policy (under the auspices of the Antarctic Treaty System), 1960-1988; and fifth, the defence of and future prospects for the policy (from United Nation's calls for South Africa's exclusion from the Antarctic Treaty System), since 1982. While resistance from inside and outside the government during the first two periods resulted from inadequacies in the South African Antarctic policy itself, resistance in the final two periods has centred upon non-Antarctic issues. As South Africa has faced ever-increasing exclusion from international governmental organizations over opposition to Its apartheid policies, organizations such as the Antarctic Treaty Organization have inevitably been drawn into the debate. As a result, the Consultative Parties of the Antarctic Treaty (of which South Africa is one of the original twelve) have been forced to deal with the following question: to what extent will political issues outside the scope of the management policies of the Antarctic Treaty Organization be allowed to affect the functioning of the Antarctic Treaty System? While the Consultative Parties continue to ponder this and the fact that South Africa's Consultative Status has become the most divisive factor within the Antarctic Treaty System, no final solutions to these issues appear likely before 1991.

Antarctic Wind Engineering deals with the effects of wind on the built environment. The assessment of wind induced forces, wind resource and wind driven snowdrifts are the main tasks for a wind engineer when participating on the design of an Antarctic building. While conventional Wind Engineering techniques are generally applicable to the Antarctic environment, there are some aspects that require further analysis due to the special characteristics of the Antarctic wind climate and its boundary layer meteorology.

The first issue in remote places like Antarctica is the lack of site wind measurements and meteorological information in general. In order to complement this shortage of information various meteorological databases have been surveyed. Global Reanalyses, produced by the European Met Office ECMWF, and RACMO/ANT mesoscale model simulations, produced by the Institute for Marine and Atmospheric Research of Utrecht University (IMAU), have been validated versus independent observations from a network of 115 automatic weather stations. The resolution of these models, of some tens of kilometers, is sufficient to characterize the wind climate in areas of smooth topography like the interior plateaus or the coastal ice shelves. In contrast, in escarpment and coastal areas, where the terrain gets rugged and katabatic winds are further intensified in confluence zones, the models lack resolution and underestimate the wind velocity.

The Antarctic atmospheric boundary layer (ABL) is characterized by the presence of strong katabatic winds that are generated by the presence of surface temperature inversions in sloping terrain. This inversion is persistent in Antarctica due to an almost continuous cooling by longwave radiation, especially during the winter night. As a result, the ABL is stably stratified most of the time and, only when the wind speed is high it becomes near neutrally stratified. This thesis also aims at making a critical review of the hypothesis underlying wind engineering models when extreme boundary layer situations are faced. It will be shown that the classical approach of assuming a neutral log-law in the surface layer can hold for studies of wind loading under strong winds but can be of limited use when detailed assessments are pursued.

The Antarctic landscape, mostly composed of very long fetches of ice covered terrain, makes it an optimum natural laboratory for the development of homogeneous boundary layers, which are a basic need for the formulation of ABL theories. Flux-profile measurements, made at Halley Research Station in the Brunt Ice Shelf by the British Antarctic Survery (BAS), have been used to analyze boundary layer similarity in view of formulating a one-dimensional ABL model. A 1D model of the neutral and stable boundary layer with a transport model for blowing snow has been implemented and verified versus test cases of the literature. A validation of quasi-stationary homogeneous profiles at different levels of stability confirms that such 1D models can be used to classify wind profiles to be used as boundary conditions for detailed 3D computational wind engineering studies.

A summary of the wind engineering activities carried out during the design of the Antarctic Research Station is provided as contextual reference and point of departure of this thesis. An elevated building on top of sloping terrain and connected to an under-snow garage constitutes a challenging environment for building design. Building aerodynamics and snowdrift management were tested in the von Karman Institute L1B wind tunnel for different building geometries and ridge integrations. Not only for safety and cost reduction but also for the integration of renewable energies, important benefits in the design of a building can be achieved if wind engineering is considered since the conceptual phase of the integrated building design process.

Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

My extensive studies throughout the maritime Antarctic allowed me to discover many new localities where the two Antarctic vascular plants (Colobanthus quitensis and Deschampsia antarctica) occur, including extending their known range to the farthest south site in the world for flowering plants. As a result of my interest in the cryptogamic flora of the maritime Antarctic, and because of my knowledge of the aquatic bryophytes of the Signy Island, I was invited to examine material of the farthest south collection of an aquatic moss by a team of American limnologists. This led to a brief review of Antarctic aquatic mosses [a related study of aquatic bryophytes from the highest Scottish lochs is referred to here, but is not included as part of the Doctorate submission]. An interesting situation has developed over the past 20 years at Signy Island. This concerns the interaction between a rapidly increasing population of fur seals (from a few dozen in 1965 to 13,350 in 1987) and the fragile and highly vulnerable plant communities. Much of the island's vegetation has been devastated or eradicated during the past five years and I have been able to quantitatively assess the changes induced by the seals by reanalysing several of precisely the same sites I studied 20 years earlier. During an ecological survey of part of Livingston Island, South Shetland Islands, and having an increasing interest in the spread of fur seals and their impact on terrestrial ecosystems, I undertood an investigation of the early history of the Antarctic fur seal industry in the 1800s and of the 'archaeological' sites (sealers' refuges) which abound on that island. My ecophysiological research included a study of the influence of growth-form on the water relations of mosses at Signy Island. Some comparable studies at a continental site are being prepared for an international symposium in Kiel, West Germany, September 1987. Several studies have been made of the chemistry of South Georgia and Signy Island plants, including one on the amount of DNA in the chromosomes of alien and native vascular species; low DNA levels in the former category of plants at South Georgia and in Europe have provided a possible explanation for the survival of certain plants under extreme climatic conditions. A review paper on plant nutrient cycling in the Antarctic and sub-Antarctic was an invited keynote presentation read at a major international symposium in South Africa. Ecological studies at both South Georgia and throughout the maritime Antarctic resulted in extensive collections of all plant groups being made. Many accounts by specialists in bryophyte and lichen taxonomy have been published based on these collections, but I have published several largely ecological papers on fungi and introduced vascular plants, including stranded trees. The combined studies of tussock grass, plant communities, the ecology and chemistry of individual native and introduced phanerogams (especially Poa annua) on South Georgia, in conjunction with a major study of the introduced reindeer on that island by another biologist, has led to a series of papers on the impact of reindeer on the vegetation. The wide spectrum of my research has allowed me to build up a high degree of first-hand knowledge and expertise in Antarctic and sub-Antarctic plant ecology, and of biological and environmental features generally. Consequently, I have written several general or popular accounts, as well as major review works. More recently I have also become involved in matters concerning conservation areas (Sites of Special Scientific Interest and Specially Protected Areas), environmental impact and conservation policy as it relates to national activities throughout the Antarctic and sub-Antarctic biomes. I co-edited a book on conservation areas in the Antarctic, writing eleven of the SPA/SSSI accounts from first-hand experience of each.

The discovery of large accumulations of meteorites in Antarctica is comparably recent, with annual collection expeditions beginning in 1974. Since then, over 50,000 meteorites have been recovered from the icefields of Antarctica. Many of those meteorites have had long residence times of up to 2 Ma mostly encased in ice; during which many of the meteorites have undergone considerable alteration. Understanding the paths of alteration allows reconstruction of original features, but additionally it gives a unique opportunity to examine a natural laboratory of cold, water-restricted alteration environments similar to those on Mars today and in its history. To fully understand the weathering of meteorites in these environments, six L6 chondrites in a variety of weathering states have been examined and characterised petrologically, chemically, and magnetically. Chemical analyses undertaken are major and trace elements measured in bulk and in spatially resolved analysis and bulk oxygen isotopes. Petrology has proven to control the weathering patterns and alteration state of the meteorite. A chemical weathering index has been developed to characterise the state of weathering using bulk chemical data, which also links with the petrological findings. This is especially evident in micro features created by shock, which promote rapid mineral breakdown and acidification of alteration fluids, which, fundamentally changes the nature and speed of the alteration. Shock generated features have created increased vulnerability to weathering and so areas that have undergone significant shock on Mars are more vulnerable to weathering and breakdown. However, the heterogeneity that is inherent to alteration environments of low water to rock ratios results in short transport distances for elements, resulting in little bulk chemical change with significant mineralogical alteration.

In this thesis RNA-sequencing tools are applied on some representatives of the antarctic trophic chain exposed to a non lethal temperature increase, as to understand and model their response to the increase in temperature expected to happen in this decade, in order to extend eventual functional conclusions to other temperate stenotherm organisms such as those living at extreme depths. RNA-sequencing consists in a set of powerful and sensible tools that allow qualitative and quantitative measurements in gene expression, pairing molecular analyses with state-of-the-art statistics and computer science. The aforementioned sensitivity, in synergy with a proper experimental design, allowed studying not only the response to a temperature increase, but also to the experimental condition itself (i.e. stabling of wild animals in tanks). The notothenioid fish Trematomus bernacchii (from which muscle, gills and brain were sampled), the scallop Adamussium colbecki (from which gills, mantle and digestive gland were sampled), the amphipod Pseudorchomene plebs and the tardigrade Acutuncus antarcticus are the models of choice of this work. In particular T. bernacchii was the most responsive of the bunch, specially in the brain tissues, where the temperature (+1.5°C increase) induced upregulation of genes involved in immune response and inflammatory state after 7 days of exposure. After 20 days of heat exposure many pathways related to synapse function and structure were altered, suggesting an on-going profound alterations in the tissue, which may also be the result of the combined effect of heat and the impossibility to avoid it in captivity. Even more profound effects were observed in the response to time in experimental tanks, as an important shift in gene expression was observed in the brain, suggesting profound changes in the neural pathways, including those involved in specific stress perception. The scallop A. colbecki did not show significant change in gene expression patterns in response to heat, but a small change was observed in the digestive gland after 20 days of experimental captivity, showing alterations in genes whose functions are mainly involved in feeding ability. Samples from the amphipod P. plebs were challenging to prepare and to analyze, as many were lost due to unfreezing during transport. Moreover the presence of a bycatch of Eusirus cf. giganteus juvenile and an high degree of parasitism from a dinoflagellate of the genus Hematodinium in all samples made it impossible to study the response of the amphipod to a warmer environment. Nevertheless, the transcriptomic data allowed the identification of an high expression of hemocyanin in E. giganteus suggesting a possible cold adaptation trait, the classification of our samples as a Orchomenid cryptic species, and the first identification of active Hematodinium parasitism in the antarctic ocean. Finally the tardigrade A. antarcticus displayed a striking sample variability, that may underlie an never described genomic variability and/or an high level of heterozygosity. This fact reduced the number of samples in the differential expression analysis, which nevertheless showed a response to short term exposure to heat with a pattern proportional to temperature in terms of fold changes of gene expression levels. The differentially expressed genes suggested that mitochondrial oxidative metabolism increased and hinted the activation of pathways related to resistance forms typical of the Tardigrada phylum. Such a response was not observed in a long term exposure to the higher temperatures, suggesting that the changes observed in short term are compensatory. ​

Mt. Morning is a 2,732 m high, Cenozoic, alkaline eruptive centre situated in the south-west corner of McMurdo Sound in the Ross Sea, Antarctica. Mt. Morning is approximately 100 km south-west of Mt. Erebus, the world's southernmost active volcano. Several Cenozoic, alkali eruptive centres in this region make up the Erebus Volcanic Province. The region is currently undergoing continental extension. Regional-scale, north-striking faulting on the northern flank of Mt. Morning has offset vertical dykes, as young as 3.9 Ma, by up to 6 m dextrally. This is consistent with the trans-extensional regime in the region. The faults also have a dip-slip component, downthrown to the east. These faults define part of the western boundary of the West Antarctic Rift System. Mt. Morning straddles the boundary between the continental rift shoulder of the Transantarctic Mountains in Southern Victoria Land, and the perceived oceanic crust of the Ross Sea. Age determination of the youngest offset dyke constrains movement in the last 3.88 � 0.05 m.y., to an average rate of 0.0015 mm per year. Volcanism on Mt. Morning is divided into two phases. Phase I was erupted between 18.7 � 0.3 and 114 � 0.2 Ma and Phase II between 6.13 � 0.20 and 0.15 � 0.01 Ma. The two phases are separated by a 5.3 m.y. period of quiescence. The geochemistry of Phase I is mildly alkaline; it is composed of volcaniclastic deposits, dykes, sills, and volcanic plugs of nepheline-basanite, nepheline-trachyte, quartz-mugearite, quartz-trachyte, and rhyolite. Phase I rocks evolved along at least two trends: a quartz normative trend, and a nepheline normative trend. Chemical variation in Phase I can be explained in part by crystal fractionation, which has been modelled using major element multiple linear regression. Phase I quartz-mugearite can fractionate to quartz-trachyte after 44% crystallisation. Quartz-trachyte can fractionate to rhyolite after a further 6% erystallisation. The models indicate that clinopyroxene + plagioclase + opaque oxides � alkali feldspar � apatite are the dominant fractionated phases. Many of the Phase I quartz normative volcanic rocks have relatively high ⁸⁷Sr/⁸⁶Sr ratios (0.70501), suggesting that assimilation, most likely of crustal material, has modified them. Phase I nepheline-basanite can fractionate to nepheline-trachyte after 68% crystallisation. Modelling indicates clinopyroxene + nepheline + olivine + opaque oxides are the dominant fractionated phases. Phase II volcanic rocks are strongly alkaline and are mapped as flows, volcaniclastic deposits, dykes, and sills. They have been erupted mainly from parasitic scoria vents and rarely from fissure vents. Rock types include picrobasalt, basalt, basanite, tephrite, hawaiite, mugearite, phonotephrite, tephriphonolite, benmoreite, and phonolite. Chemical variations in the Phase II volcanic rocks can be explained by simple fractionation. Phase II picrobasalt can fractionate to phonotephrite after 78% crystallisation. Phonotephrite can fractionate to phonolite after at least 35% crystallisation, depending on which of several multiple linear regression models are selected. Fractionation is dominated by the removal of clinopyroxene + plagioclase + nepheline + olivine + opaque oxides � apatite � kaersutite. Volcanic rocks in the Erebus Volcanic Province are strongly alkaline on a silica versus total alkalis plot, similar to the Phase II volcanic rocks from Mt. Morning. Mildly alkaline rocks of Phase I are, to date, unique within the Erebus Volcanic Province. Bulk rock isotope ratios of ⁸⁶Sr/⁸⁷Sr (0.70307 - 0.70371 and 0.70498 - 0.70501), �⁴�Nd/�⁴⁴Nd (0.512650 - 0.512902), and �⁰⁶Pb/�⁰⁴Pb (18.593 -20.039) show that the majority of Mt. Morning volcanic rocks lie on a mixing line between HIMU (high-[mu]; enriched in �⁰⁶Pb and �⁰⁸Pb and relatively depleted in ⁸⁶Sr/⁸⁷Sr values) and DM (depleted mantle; high �⁴�Nd/�⁴⁴Nd, low ⁸⁶Sr/⁸⁷Sr, and low �⁰⁶Pb/�⁰⁴Pb). This is similar to the majority of volcanic rocks from the SW Pacific, including Antarctica and New Zealand. Mt. Morning volcanic rocks have tapped this broadly common mantle reservoir. There are variations in radiogenic isotope ratios between Mt. Morning and Mt. Erebus. There are also differences between the incompatible element ratios in volcanic rocks from Mt. Morning, Mt. Erebus, and White Island (a third eruptive centre in the Erebus Volcanic Province), suggesting heterogeneity in the mantle beneath the Erebus Volcanic Province. Significant chemical differences are also noted between ultramafic xenoliths collected from Mt. Morning and from Foster Crater only 15 km away. This suggests a deca-kilometre, possibly even kilometre-scale, heterogeneity in the mantle. Such small-scale chemical differences appear difficult to reconcile with large-scale plume hypotheses for the initiation of volcanism in the Erebus Volcanic Province. Instead, volcanism is much more likely to be related to numerous small plumes, or the preferred hypothesis, metasomatism and amagmatic rifting, followed by decompression melting of upwelling mantle and volcanism during transtensional lithospheric rifting. This latter model is supported by a lack of regional updoming expected with a plume(s), and fits models of localised extension proposed in this thesis. Calc-alkaline and alkaline igneous xenoliths, of felsic to mafic crustal material, have been collected from Mt. Morning. U-Pb geochronology (545.4 � 3.7 Ma and 518.6 � 4.4 Ma) on crustal xenoliths from Mt. Morning illustrate that the basement is Cambrian. Bulk rock chemistry of crustal xenoliths has similarities to compositions reported for Ross Orogen rocks, suggesting the Mt. Morning volcanic edifice is built on a basement that is composed of Cambrian Ross Orogen rock types. Quartz-bearing felsic granulite xenoliths with greater than 70 weight percent silica, collected from Mt. Morning, suggest that part of the basement is felsic. This is the only occurrence of felsic xenoliths reported to date east of the present day coastline of Victoria Land. Mt. Morning crops out less than 25 km from the known northern end of the Koettlitz Glacier Alkaline Province in the Transantarctic Mountains. The partially alkaline basement beneath Mt. Morning suggests the province may continue beneath part of Mt. Morning. The mantle beneath Mt. Morning can be characterised as anhydrous and otherwise largely unmetasomatised, which is atypical of xenoliths collected from the western Ross Sea. Only a handful of Mt. Morning xenoliths show petrographic evidence of metasomatism, these include modal phlogopite, apatite, Fe-Ni sulphide, and plagioclase (in pyroxenite xenoliths), suggesting metasomatising fluids occur discretely in this region. Where present, the metasomatic fluid(s) beneath Mt. Morning are enriched in Ba, LREEs, Th, U, P, Fe, Ni, S, and K, and depleted in Ti relative to the metasomatic fluid composition described at nearby Foster Crater. Oxygen fugacity (fO₂) of the Antarctic shallow mantle has been measured from xenoliths collected from Mt. Morning, where fO₂ was demonstrated to be strongly dependant upon spinel Fe�⁺ content that was measured using Mössbauer spectroscopy, and calculated from the olivine-orthopyroxene-spinel oxybarometer. fO₂ in the rifted Antarctic mantle varies between 0.1 and -1 log units relative to the fayalite-magnetite-quartz buffer and is coupled to melt depletion, with increasing degrees of melt extraction resulting in a more oxidised mantle. This range of upper mantle fO₂ is commonly observed in continental rift settings worldwide. The mantle beneath Mt. Morning is composed of, in increasing degree of fertility, dunite, harzburgite, and lherzolite. Xenoliths representing discrete samples of this mantle have mostly crystallised in the spinel stability field of the mantle at pressures of approximately 15 kb and temperatures between 950 - 970 �C. Symplectites of spinel and pyroxene have been interpreted as petrographic evidence that some of the spinel peridotite originated in the garnet stability field of the mantle. Rare plagioclase-bearing spinel lherzolite (plagioclase lherzolite) is also present in the mantle beneath Mt. Morning, which crystallised at temperatures of between 885 and 935 �C at 5 kb. The Mt. Morning peridotite xenoliths plot along the pre-defined geotherm for the Erebus Volcanic Province, strongly supporting it as the appropriate choice of geothermal gradient for south-west McMurdo Sound. Mineral and bulk rock compositions are nearly identical between the plagioclase lherzolite xenoliths and spinel lherzolite xenoliths. Mineral and bulk rock chemistry suggest it is unlikely that the plagioclase is due to metasomatism. Petrographic evidence and mass balance calculations suggest that the plagioclase lherzolite has crystallised via a sub-solidus (metamorphic) transition from spinel lherzolite upon decompression and upwelling of the mantle. The occurrence of plagioclase lherzolite beneath Mt. Morning could be explained by lithospheric scale uplift along faults that define the western margin of the West Antarctic Rift System. Plagioclase lherzolite has also been collected and described from White Island. White Island is also interpreted to straddle lithospheric scale faults. Rifting and buoyant uplift is sufficient to explain the presence of plagioclase lherzolite in the Erebus Volcanic Province. Plagioclase lherzolite has also been described from Mt Melbourne, an eruptive centre in Northern Victoria Land. Known occurrences of plagioclase lherzolite from the western shoulder of the Ross Sea now cover an area 430 km long and 80 km wide. This is one of the largest provinces of plagioclase peridotite worldwide so far reported.

Correct species identification is fundamental to all areas of biology, but particularly the policy related areas of conservation and fisheries management. To enable guidelines to be developed for environmental management and conservation, such identifications need links to studies of the evolutionary history, biological factors and environmental influences driving species divergence and population dynamics for the target species. This study concerns two genera of gadiform fish, Muraenolepis and Macrourus, found in southern temperate and Antarctic waters, with a single species, Macrourus berglax, present in the North Atlantic. With similar distribution patterns to toothfish species, Dissostichus eleginoides and D. mawsoni, they are a major food source and by-catch of the toothfish fishery. Both are slow growing and long lived, with different evolutionary histories, life expectancies and strategies for reproduction. For both genera, the accuracy of morphological keys, number of described species and their distribution is under debate. This study has identified specimens to species level using both morphological and genetic techniques, redefining the range for morphological features and taxonomic keys. For Muraenolepis, this has clarified confusion over Mu. marmoratus and Mu. microps being a single species, confirmed some mis-identification from sexual dimorphism and provided genetic evidence for the recently described species Mu. evseenkoi. For Macrourus, this work has identified a new species, now named Ma. caml, and found that Ma. holotrachys and Ma. berglax are genetically identical, raising the question of bipolar distribution or recent divergence. The low level of genetic variation within both species suggests a recent evolution and expansion into Antarctic waters. Similar geographic species limits imply common processes influencing divergence, with the oceanographic fronts as potential barriers. Further investigation of niche overlap and fine scale population structure are required to fully understand the processes driving speciation and provide the underlying data required for fisheries management.

I developed and tested a protocol for determining the sex of individual pinnipeds using the sex-chromosome specific genes ZFX and ZFY. I screened a total of 368 seals (168 crabeater, Lobodon carcinophagus; 159 Weddell, Leptonychotes weddellii; and 41 Ross, Ommatophoca rossii) of known or unknown sex and compared the molecular sex to the sex assigned at the time of collection in the Ross and Amundsen seas, Antarctica. Discrepancies ranged from 0.0% - 6.7% among species. It is unclear, however, if mis-assignment of sex occurred in situ or in the laboratory. It also is possible, however, that the assigned morphological and molecular sex both are correct, owing perhaps to developmental effects of environmental pollution. I sequenced a portion (ca 475 bp) of the mitochondrial control region of Weddell seals (N = 181); crabeater seals (N = 143); and Ross seals (N = 41). I resolved 251 haplotypes with a haplotype diversity of 0.98 to 0.99. Bayesian estimates of Θ from the program LAMARC ranged from 0.075 for Weddell seals to 0.576 for crabeater seals. I used the values of theta to estimate female effective population sizes (NEF), which were 40,700 to 63,000 for Weddell seals, 44,400 to 97,800 for Ross seals, and 358,500 to 531,900 for crabeater seals. Weddell seals and crabeater seals had significant, unimodal mean pairwise difference mismatch distributions (p = 0.56 and 0.36, respectively), suggesting that their populations expanded suddenly around 731,000 years ago (Weddell seals) and around 1.6 million years ago (crabeater seals). Both of these expansions occurred during times of intensified glaciations and may have been fostered by expanding pack ice habitat. Autosomal microsatellite based NEs were 147,850 for L. Weddellii, 344,950 for O. rossii, and 939,600 for L. carcinophagus. I screened one X-linked microsatellite (Lw18), which yielded a larger NE estimate for O. rossii than the other two species. Microsatellite NE estimates are compared with previously published mitochondrial NE estimates and this comparison indicates that the Ross seal may have a serially monogamous system of mating. I find no sign of a recent, sustained genetic bottleneck in any of the three species.

This thesis is concerned with the lived experience of placemaking in Argentina’s Antarctic gateway port Ushuaia. Based on 12 months ethnographic fieldwork, it explores the relations between tourism, urban development, and socio-economic difference. As such, it investigates how agents from across the social spectrum conceive of, and construct their sense of place “at the end of the world”. As the world’s southernmost city, Ushuaia is attractive to tourists for its stunning landscapes, unique location, and strategic proximity to Antarctica. However, the image of a friendly tourist destination crucial to everyday life in this Patagonian city is contested by its stakeholders. This thesis looks beyond the image presented to tourists to explore frictions among residents, the city council, and touristic enterprises. Ushuaia is revealed as an urban location beset by growing unrest due to issues of population growth and social polarization. This is analyzed in relation to its geopolitical significance for the Argentine state, territorial struggles with Chile, and economic incentives for in-migration. Consequently, this thesis considers the dynamic and shifting character of the city’s population through an engagement with economic and lifestyle migrants, including those dwelling in non-legal settlements, and tourists who occupy Ushuaian space alongside more longstanding citizens. The thesis demonstrates how conflicting views collide regarding issues of urbanization, industrialization, tourism, and environmental conservation, analyzed in relation to the interests and concerns of different social constituencies. Through extensive interviewing with a diverse array of social actors, this thesis also explores the different levels of economic and socio-cultural attachment to Antarctica, suggesting a schism between Ushuaia’s touristic representation, Antarctic alignment, and the needs and interests of its inhabitants. This thesis, then, explains the diverging place-based ideas and aspirations of different social groups in relation to the governmental, socio-economic, and socio-cultural forces implicated in placemaking.

"2003".
Thesis (PhD)--Macquarie University, Division of Environmental & Life Sciences, Department of Biological Sciences, 2004.
Bibliography: leaves 136-160.
Introduction: The Antarctic environment; Antarctic inhabitants; Microfungi; Identification of microfungi; Physiological factors affecting Antactic microfungi; Flow cytometry and microfungi; Hydrolytic enzymes of industrial interest; Isolation of genes from microfungi; Aims of this study -- Materials and methods: Fungal strains and cultivation conditions; Molecular identification of fungal isolates; Fungal physiology; Hydrolase activity of secreted proteins; Gene cloning and expression -- Results and discussion: Microfungal identification; Physiological factors affecting Antarctic microfungi; Activity in microfungi when grown on solid media; Characterisation of hemicellulases from selected Antarctic microfungi; Cloning of an Antarctic Penicillium allii lipase gene and its expression in Trichoderma reesei -- Conclusions and future prospects.
The Antarctic occupies that region of the planet that falls below the 60th parallel of South latitude. Although it has been frequented by adventurers, journeyman scientists and tourists for the past 100 years, the Continent has remained virtually unoccupied. The intense cold, the absence of human occupation and the limited range of local higher animal species have combined to create the impression that the Continent is virtually devoid of life. -- Although the microbiota of the Antarctic has attracted some small level of attention in the past, the examination of filamentous microfungi has been largely overlooked and fallen to a small group of dedicated investigators. In this study it will be shown that far from being an insignificant component of the Antarctic network, microfungi represent a potentially large and so far untapped bioresource. -- From just 11 bryophyte samples collected at four sites in the Ross Sea/Dry Valleys region of Southern Antarctica, some 30 microfungal isolates were recovered. Using molecular techniques, the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) was sequenced to reveal no less than nine unique microfungal species. For only two of these species did the ITS sequence data produce a 100% match with records held on the public databases. This investigation also highlighted the problems inherent in the traditional morphological identification system which are now being perpetuated in the molecular database records. -- A set of seven notionally identified isolates obtained from ornithogenic soil samples gathered in the Windmill Islands in Eastern Antarctica (offshore from the Australian Antarctic Division's Casey Station) were also subjected to molecular identification based on ITS sequence data. Each of the seven isolates was identified as a unique species; six were cosmopolitan in nature and the one remaining bore very little resemblance at the molecular level to any of the recorded species although it was provided with an epithet commonly used in the identification of Antarctic microfungal species. -- To evaluate their potential as a bioresource, samples of Antarctic microfungi were examined to determine if the same physiological factors common to mesophilic species also applied to their Antarctic analogues. It is known that when placed under stress, trehalose can act as a protectant against cold (cryoprotection) and dehydration in mesophilic yeasts and fungi. The level of trehalose produced by the Antarctic isolates and their mesophilic analogues when subjected to stress was compared. A similar comparison was made for the production of glycerol which is well established as a compatible solute providing protection to mesophilic species against osmotic stress. Only in the case of trehalose production by an Antarctic Embellisia was there any indication that either of these two compounds could play a significant role in providing protection to the Antarctic fungi against the rigours of their environment, which leaves open to question what in fact does. -- In the course of investigating the means by which Antarctic microfungi guard against the damage which can ensue when subjected to oxidative stress, flow cytometry was introduced as an investigatory tool. It was established that there is a window of opportunity during which flow cytometry can be used to undertake a detailed analysis of the early stages of fungal growth from germination through hyphal development. -- Of major significance in determining the potential of Antarctic microfungi as a resource is their ability to produce new and novel enzymes and proteins. The microfungal isolates were screened for hydrolytic activity on solid media containing indicative substrates and proved to be a fruitful source of enzymes active over a range of temperatures. A detailed characterisation of two hemicellulases, β-mannanase and xylanase, secreted into a liquid medium by a subset of the Antarctic fungi and a high producing mesophilic reference strain permitted direct comparisons to be made. It was shown that the maximum hemicellulase activity of the Antarctic strains occurred at least 10°C and as much as 30°C lower than that of the reference strain and that mannanase activity for two of the Antarctic isolates exceeded 40% of their maximum at 0°C. These assay results highlight the potential of Antarctic microfungi to yield novel cold-active enzymes. -- As a final measure of the capacity of the Antarctic to yield novel enzymes from its microfungal stock, a lipase gene was selected as a target for isolation and expression in a heterologous fungal host. Using PCR techniques, the gene of interest was isolated from an Antarctic isolate of Penicillium allii, transformed into the mesophilic production host Trichoderma reesei and the active protein successfully produced in the growth medium. The recombinant lipase was assayed and found to exhibit novel characteristics consistent with a cold-adapted enzyme.
Mode of access: World Wide Web.
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Soil samples from 8 sites (7 contaminated and 1 reference) at Marble Point and Scott Base were assessed for heavy metal pollution. Samples were acid leached and analysed by differential pulse anodic stripping voltammetry and electrothermal atomic absorption spectrometry for lead, zinc, cadmium and copper. Weathering of these metals from point source contaminants was established. Sequential leaching was then performed to evaluate the potential fate ofthe contaminants using the same techniques. Studies were limited to exchangeable fraction and metal fractions bound to carbonates, oxides and organic matter. In the majority of the samples, the oxide fraction formed the largest sink for extractable lead and zinc. In addition, increase in organic matter was observed for some soils. Low levels of extractable aluminium were found, confirming the limited extent of weathering possible in the cold, arid Antarctic climate. Two modes of origin of soluble salts were inferred from levels of sodium, potassium, calcium and magnesium detected in the soils.

Approved for public release; distribution unlimited.
The Antarctic Treaty of 1959, ratified in 1961, is subject to review in 1991. This thesis presents a negotiating position for the United States in the event the Treaty is reviewed. To do so, it examines important aspects of the review process, presenting a broad view of the issues, parties, and strategies facing the United States in these negotiations. In addition, major issues which have evolved over the past 30 years within the parameters of the Antarctic Treaty System are explored, as well as areas of potential future conflict. The positions of those countries within and those outside the Antarctic Treaty System are identified in order to anticipate areas of conflict and consensus during the negotiation process. Additionally, some planning implications are explored which highlight operational support areas of concern. The thesis concludes that it is in the United States' interest for the Antarctic Treaty to continue in its present form and presents a negotiating strategy to achieve that end.

Quaternary diatom-rich laminated sediments, found in Antarctic inner shelf depressions, contain high-resolution records of climate change. Diatom assemblages and sediment fabric of four laminated intervals were examined with a scanning electron microscope (using backscattered and secondary electron imagery) and light microscope in this study. Deglacial Palmer Deep laminated sediments (western Antarctic Peninsula) are composed of alternating biogenic diatom ooze and diatom-bearing terrigenous laminae. These laminae are interpreted as spring and summer signals respectively, with negligible winter deposition. Sub-seasonal species specific sub-laminae are observed repeatedly through the summer laminae. Tidal cycles, high storm intensities and / or intrusion of Circumpolar Deep Water onto the continental shelf create variation in shelf waters, enhancing species specific productivity through the summer. Post-glacial Mertz Ninnis Trough laminated sediments (East Antarctic Margin) are composed of five lamina and one sub-lamina types. During deposition the Mertz Glacier Polynya was active and Adelie Land Bottom Water formation was strong. Mid-Holocene Mertz Ninnis Trough laminated sediments are composed of five lamina types. Sea ice cover and sea ice formation was reduced relative to post-glacial times. The Mertz Glacier Polynya was not as active as in the post-glacial and Adelie Land Bottom Water formation was lower. Late-Holocene Durmont d'Urville Trough laminated sediments (East Antarctic Margin) are composed of eight lamina and one sub-lamina types. Sea ice cover was extensive and persistent in the late-Holocene. Warmer periods occurred during the transition from mid-Holocene Climatic Optimum to cooler late-Holocene climatic conditions. The types of lamina and sub-lamina formed in all four laminated intervals are controlled by seasonal sea ice cover, nutrient levels and light levels, which are in turn influenced by climate and oceanography. The Western Antarctic Peninsula and East Antarctic Margin laminated sediments give an insight into oceanographic responses to climatic change and variation through the Quaternary around the Antarctic margin.

The Southern Ocean plays a major role in the global overturning circulation, providing an important route for the return flow of deep water subducted in the North Atlantic. The World Ocean Circulation Experiment (WOCE) provided an unprecedented picture of the state of the world’s oceans and set new standards for high quality in-situ hydrographic data. This study combines the existing WOCE data set with new hydrographic sections, and output from global and regional ocean models to examine the mean state of the Southern Ocean circulation and the balance of fluxes around the Antarctic Circumpolar current. A historical data set in the region of Drake Passage is examined to study the large-scale water mass variability between 1926-2005. The water mass properties of the Lower Circumpolar Deep Water is constant within error bounds throughout the data set. A warming and freshening signal in the surface waters from 1997-2005 to the north of the Sub-Antarctic Front along SR01b is also presented. The major part of this work is based around an inverse study of the Southern Ocean that combines the WOCE data-set with contemporary sections, and other forcing fields to examine the balance of fluxes throughout the Southern Ocean. The study examines the effect of different parameterisations of the dianeutral mixing in the Southern Ocean, in light of the differing views of localised deep turbulent mixing from observations, and an adiabatic ocean interior from residual mean studies, The freshwater balance in the model is presented and its implications on the water mass formation and transformation of the upper and lower cells of the overturning circulation is discussed in detail.

The nearshore Antarctic marine environment is unique, characterised by low but constant temperatures that contrast with an intense peak in productivity. As a result of this stenothermal environment, energy input has a profound ecological effect. These conditions have developed over several millions of years and have resulted in an animal physiology that is highly stenothermal and sometimes closely coupled with the seasonal food supply, e.g. reproductive periodicity and food storage. Therefore, Antarctic marine animals are likely to be amongst the most vulnerable species worldwide to environmental modifications and can be regarded as highly sensitive barometers for change. Reproductive success is a vital characteristic in species survival and evaluation of change in reproductive condition with time key to identifying vulnerable taxa. Characterising reproductive success with time is a major requirement in predicting species response to change and the early stages of species loss. Some invertebrates are highly abundant in shallow water sites around the Antarctic and form conspicuous members of the Antarctic benthos. Three common echinoderms and one nemertean were sampled from sites adjacent to the British Antarctic Survey’s Rothera Research Station, Adelaide Island, on the West Antarctic Peninsula between 1997-2001. Reproductive patterns were determined by histological analyses of gonad tissue. This study provided further evidence for inter-annual variation in Antarctic gametogenic development, which appeared to be driven to some extent by trophic position and reliance on the seasonal phytoplankton bloom. The largest variation in reproductive condition was demonstrated for the detritivorous brittle star, Ophionotus victoriae. The seasonal tempos of this echinoderm have been attributed in part, to the seasonal sedimentation events common in the high Antarctic. The reproductive patterns in the scavenging starfish, Odontaster validus and the predatory nemertean, Parborlasia corrugatus showed less inter-annual variation. The de-coupling of these invertebrates from the intensely seasonal phytoplankton bloom appeared to partially account for the reproductive trends observed. The lack of inter-annual variation in the reproduction of the filter-feeding sea-cucumber, Heterocucumis steineni, was somewhat counterintuitive, although problems with sample processing probably accounted for the majority of this anomaly. Echinoderms were also collected during the Antarctic summer field seasons in 2003 and 2004. A series of fertilisation success studies were undertaken comparing the adaptations in an Antarctic and an equivalent temperate starfish to achieve optimal numbers of fertilised eggs, and elemental analyses were used to estimate the nutritional and energetic condition of the bodily and reproductive tissues in two Antarctic echinoderms. Fertilisation studies indicated that Antarctic invertebrates require 1-2 orders of magnitude more sperm to ensure optimal fertilisation success. These sperm tended to be long-lived and capable of fertilising eggs 24+ hours after release. The study suggested that synchronous spawning, aggregations and specific pre-spawning behaviour are employed to help counter the deleterious effects of sperm limitation. The Antarctic eggs and sperm were also highly sensitive to even small modifications in temperature and salinity, affecting the number of eggs fertilised. Such stenothermy is of particular relevance if the 1-2ºC rise in global temperature, predicted over the next century, is realised. Biochemical composition of body components of two species of Antarctic echinoderm indicated a significant difference in the composition between the male and female gonad, particularly in the Antarctic brittle star Ophionotus victoriae. The ovaries contained a much larger proportion of lipid compared to the testes, and demonstrated a distinct seasonality in composition. Higher levels of lipid were observed in the ovary during the austral winter coincident with a period of reproductive investment and maturing oocytes in the gonad. O. victoriae exhibited lower amounts of lipid in the late austral spring suggesting the removal of mature oocytes from the ovary through spawning. The seasonality in composition and the high levels of lipid and protein measured in the ophiuroid gut tissue, suggested the gut might play a role in providing material and energy for metabolic function and possibly gametogenesis; higher lipid levels were apparent during the period of seasonal phytodetrital flux. The role of the pyloric ceaca in asteroids as a nutrient storage organ was also evident in the high levels of both protein and lipid observed in this bodily component in the star fish, Odontaster validus.

Microorganisms play a crucial role in supporting biodiversity, maintaining marine and terrestrial ecosystems at the crux of the nutrient cycle. They are the most diverse and abundant of all living creatures, yet little is understood about their distribution or their intimate relationship with the environment. Antarctic ecosystems are among the most simple on Earth; with basic trophic structuring and the absence of many taxonomic groups, they are also isolated geographically with small patchy areas of nutrient inputs. In this instance, Antarctica becomes a pristine laboratory to examine the ecological paradigms already applied to macro-organisms, to determine if common biological laws govern the distribution of biology globally. The decline of biodiversity with increasing latitude is one such observation in the distribution of macro-organisms. In this study, soil microbial community samples were retrieved over a latitude of 56 to 72 °S across the Antarctic Peninsula region. This is a region of special interest due to a rapidly warming climate with mean temperatures increasing at several times the rate of mean global warming. Sites were biologically and environmentally profiled and data used in a variety of multivariate analysis in order to identify spatial trends and infer mechanisms that may be driving Antarctic terrestrial food webs; or where this was not possible, the areas where focus was needed to increase the information profile to allow this. Results indicate a lack of linear latitudinal gradient in microbial diversity, but do show a correlation with environmental heterogeneity; analysis of site diversity identified a gradient between warmer wetter areas, and areas synonymous with cold desert environment at 66⁰S, supported by both phylum composition and indicative soil chemistry. This was confirmed through principal co-ordinates of neighbours’ matrices analysis (PCNM), with distinct regions of community composition being identified when viewed with respect to environmental variables. Considering an overview of diversity with respect to environmental variables provided additional structure to test hypotheses about nutrient webs through structural equation modelling (SEM), and inferred that areas of patchy nutrient input exist and by means of ornithogenic guano additions promote higher C and N availability, increasing microbial abundance and richness.

The Antarctic continental margin contains a diverse range of continental slope morphologies, including iceberg keel marks, gullies, channels, mass-wasting features (slides, slumps), ridges, furrows, mounds and trough mouth fans. These features vary significantly in morphology, with bedforms varying in size (width, amplitude and length), shelf incision, sinuosity, branching order, spatial density and cross-sectional shape. The processes which form these features and the environmental controls influencing their morphology are not well documented or well constrained. Understanding the processes operating on the Antarctic continental margin is essential for interpreting seafloor erosion patterns, continental margin evolution, slope instability and sediment core records from the continental slope and rise. Through quantitative analysis of multibeam bathymetric data along >2670 km of the outer shelf and upper-slope of high latitude continental margins, five distinct Antarctic gully types are identified. Gully morphology was found to vary with local slope character (slope geometry, gradient), regional factors (location of cross-shelf troughs, trough mouth fans and drainage basin size), sediment yield and ice-sheet history. Most gullies are likely formed by: (1) flows generated as a result of the release of subglacial meltwater from beneath an ice-sheet grounded to the shelf edge during glacial maxima; (2) turbidity currents initiated by intense iceberg scouring; or (3) small-scale mass-wasting. Erosion by cascading dense water overflow does not form the deeply incised and V-shaped gullies that occur over much of the Antarctic continental margin. A comparison of some Arctic and Antarctic gully morphologies shows that the Antarctic gullies have much deeper mean incision depths and greater shelf-incisions, suggesting that they either formed over significantly longer periods, or by a greater release of meltwater in the areas with greater gully incision depths. The first morphological analysis of the southern Weddell Sea outer shelf and upper slope is presented. Two large and relatively recent submarine slides occur on the Crary Fan, the first Quaternary slides to be documented on an Antarctic trough mouth fan. These slides provide evidence for recent large-scale mass-wasting events on the Antarctic continental margin. The interpretation of bedforms on the outer shelf of the southeastern Weddell Sea provide insight into the timing and extent of past ice and points to grounded ice near to the shelf edge during the Late Quaternary.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2009.
Additional advisors: Bill J. Baker, James B. McClintock, Donald D. Muccio, Robert W. Thacker. Description based on contents viewed June 3, 2009; title from PDF t.p. Includes bibliographical references.

Der Südozean ist die Schlüsselregion zur Kenntnis der neogenen Klimaentwicklung. In diesem Zusammenhang ist die Untersuchung von planktonischen Gemeinschaften in Hinblick auf die Umweltentwicklung von großer Bedeutung. In antarktischen neogenen Sedimenten sind Radiolarien reichlich, in großer Diversität und einheitlich gut erhalten. Sie sind nicht nur perfekte Testobjekte für paläobiologischen Studien, sondern auch eine wichtige Quelle für eine verbesserte Biostratigraphie – bisher behinderte nämlich das Fehlen einer verlässlichen Geochronologie detaillierte Studien. Es wurde ein Datensatz aller Taxa von mehreren Standorten des Südozeans gesammelt: für alle der 98 Proben je ca. 7000 Radiolarien. Die Fauna enthält ca. 500 Arten (inclusive 120 neuer Taxa). Die Untersuchung der Makroevolutionsgeschichte dieser Fauna zeigt, dass eine wesentliche ökologische Umwälzung, ohne Aussterbeereignis, bezogen auf den Verlauf der Artengleichheit und den Anstieg der Gattung Antarctissa, bei ca. 8 Ma erfolgte. Dann, 3 My später, folgte ein wesentlicher Diversitätsverlust. Obwohl das ökologische Ereignis eventuell mit einer Änderung der Primärproduzenten assoziiert sein kann, ist der auslösende Faktor des Diversitätsabfalls unbekannt. Außerdem zeigt der Vergleich zwischen der Diversitätsgeschichte dieser Fauna und einer Paläodiversitätsrekonstruktion südozeanischer Faunen, beruhend auf der Neptune Datenbank, daß der generelle Verläufe mit den Probenteilungsmethodologien nachgezeichnet wird, jedoch diese Methodologien aufgrund grober Verzerrungen nicht geeignet für Detailstudien sind. Schließlich wurde eine biostratigraphische Analyse für die komplette Fauna vom Obermiozän bis Pliozän durchgeführt. Obwohl diese Analyse noch vorlaüfig ist, zeigt sich eine Angleichung des aktuellen Altersmodells um mehr als 1 My. Diese Studie zeigt auch 94 neue, sichere Ereignisse, die für die stratigraphische Einordnung der Antarktischen Sedimente genutzt werden können.
The Southern Ocean is the key to understand the Neogene climate evolution. Unfortunately the lack of a robust geochronological framework has hindered precise studies. Equally of interest is understanding how planktonic communities changed in relation with the evolution of these environments. Radiolarians are abundant in Antarctic Neogene sediments, diversified and consistently well-preserved. They should constitute not only an ideal testing ground for paleobiological studies but also a major resource for improved biostratigraphy. In this study, a quantitative, taxonomically-complete dataset have been collected in various sites of the Southern Ocean, using 98 samples and ca. 7000 specimens per sample. Ca. 500 species were uncovered in this fauna, including 120 new to science. The study of the macroevolutionary history of this fauna reveals that a significant, extinctionless ecological turnover, linked to a decrease in the evenness of the species'' abundances and the rise of genus Antarctissa to dominance, occured at ca. 8 Ma, followed 3 My later by a significant diversity loss. Although the ecological event can be tentatively associated with a regional change in the composition of primary producers, the triggering event of the diversity loss is yet to be found. The whole-fauna diversity history was compared to paleodiversity reconstructions computed using subsampling methodologies from the occurrences gathered in the Neptune database. The comparison shows that the main trends are retrieved by the subsampling procedures but also that substantial distortions make them poorly suited for detailed studies. Finally a biostratigraphical analysis was conducted on this whole-fauna dataset for the late Miocene - Pliocene sequence. Although this analysis is still very much preliminary, it shows a coherent readjustement of the current age models by more than 1 My. This study also shows that 94 events seem reliable enough to be used to correlate Southern Ocean sites together.

The population structure and feeding dynamics of the hyperiid amphipod, Themisto gaudichaudii, was investigated during two cruises of the South African National Antarctic Programme conducted in the Indian sector of the Polar Frontal Zone during austral autumn (April) 2004 and 2005. During the 2004 cruise the frontal features that delimit the PFZ converged to form a single distinctive feature. In 2005, the research cruise was conducted in the vicinity of a cold-core eddy which was spawned from the Antarctic Polar Front. Total mesozooplankton abundance and biomass during the 2004 study ranged from 55.19 to 860.57 ind. m⁻³, and from 2.60 to 38.42 mg dwt m⁻³, respectively. In 2005 the abundance and biomass ranged from 23.1 to 2160.64 ind. m⁻³, and from 0.76 to 35.16 mg dwt m⁻³, respectively. The mesozooplankton community was numerically dominated by copepods, pteropods, and ostracods during both surveys. The abundance and biomass of Themisto gaudichaudii in the region of investigation was < 0.2 ind. m⁻³ (range 0.01 to 0.15 ind. m⁻³) and < 0.06 mg dwt m⁻³ (range 0.02 to 0.06 mg dwt m⁻³) during 2004, while in 2005 the abundance and biomass of the amphipod ranged from < 0.01 to 0.2 ind. m⁻³ and < 0.01 to 0.04 mg dwt m⁻³, respectively. These values correspond to < 1% of the total mesozooplankton abundance and biomass during both surveys. T. gaudichaudii exhibited no significant spatial patterns in abundance, biomass and total length during both 2004 and 2005 (p > 0.05 in all cases). A key feature of the two investigations was the virtual absence of juveniles (total length < 15 mm) among the amphipod population, supporting the suggestion that they exhibit strong seasonal patterns in reproduction. Gut content analysis during both years indicated that for both the male and female amphipods’, copepods were the most prevalent prey species found in stomachs, followed by chaetognaths and pteropods. Results of electivity studies indicate that T. gaudichaudii is an opportunistic predator, generally feeding on the most abundant mesozooplankton prey. Results of in vitro incubations indicated that the total daily feeding rate of T. gaudichaudii during 2004 ranged from 11.45 to 20.90 ind. m⁻³ d⁻¹, which corresponds to between 0.12 and 1.64% of the total mesozooplankton standing stock. In 2005, the feeding rate ranged between 0.1 and 1.73% of the total mesozooplankton standing stock. The low predation impact of T. gaudichaudii during this study can be related to their low abundances and high interannual variability throughout the region of investigation.

Thesis (MA)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: This thesis deals with the nature and historical development of tourism and leisure activities that have been conducted within the Antarctic and sub-Antarctic regions from 1895 to present. First, it traces the brief history of human involvement with the Antarctic continent, which culminated in a surge of ostensibly scientific exploration with jingoistic overtones which has become widely known as the ‘Heroic Age’ of Antarctic exploration. These explorers’ adventures, taken up by the popular press and promoted by jingoistic governments, popularised a particular conception of the continent to the point where people imagined going to see it for themselves, vicariously reliving their heroes’ adventures in the form of tourism. The rise of formal governance on the Antarctic is then traced and used to explain how this provided for regular tourist activities to commence since the mid-1960s. The changing nature of tourism to the region is surveyed, as well as its impact on the environment. Finally, Marion Island, South Africa’s Sub-Antarctic Island, is discussed through the lens of tourism and leisure. Tourism has not been permitted on the island, so it offers a useful comparison with other sub-Antarctic islands that do allow tourists to visit. The thesis also deals with masculinity, as the Antarctic and sub-Antarctic were male dominated environments for the majority of human interaction with these regions. The thesis argues that the accumulation of knowledge in these areas by scientists has (perhaps counter-intuitively) led to the creation of the tourism industry, which would not have been able to flourish without the constant human presence secured by the scientific bases scattered around the Antarctic. Finally, this thesis offers a form of autoethnographic historical investigation, as an insider/outsider dichotomy (between “scientist” and “tourist”) was explored through embedded research, where scientists and support personnel are viewed as insiders on the one hand, and tourists are regarded as outsiders on the other.
AFRIKAANSE OPSOMMING: Hierdie tesis handel oor die aard en historiese ontwikkeling van toerisme en ontspannings aktiwiteite wat binne die Antarktiese en sub-Antarktiese gebiede onderneem is vanaf 1895 tot die hede. Dit behandel eerstens die kort geskiedenis van menslike betrokkenheid op die Antarktiese vasteland, wat uitgeloop het op 'n oplewing van oënskynlik wetenskaplike eksplorasie met nasionalistiese konnotasies wat wyd bekend geword het as die ‘Helde Era’ van Antarktiese verkenning. Hierdie ontdekkingsreisigers se avonture, soos weerspieël in die populêre pers en bevorder deur nasionalistiese regerings, het 'n bepaalde opvatting van die vasteland gewild gemaak. Soveel so dat dit mense beweeg het om as toeriste die gebied te besoek en op die wyse hul helde se avonture te herleef in die vorm van toerisme. Die opkoms van die formele beheer van die Antarktiese vasteland word dan nagespeur en gebruik om aan te dui hoe dit teen die middel 1960’s tot aktiewe toerisme in die gebied aanleiding gegee het. Die veranderende aard van toerisme na die streek, sowel as die impak daarvan op die omgewing word ondersoek. Ten slotte, word Marion Island, Suid-Afrika se Sub-Antarktiese eiland bespreek deur die lens van toerisme en ontspanning. Toerisme word nie op die eiland toegelaat nie, wat hom leun tot 'n nuttige vergelyking met ander sub-Antarktiese eilande wat wel toerisme toelaat. Aangesien die meerderheid van die menslike interaksie met Antarktieka en die sub- Antarktiese eilande deur mans gedomineer is, handel die tesis ook oor manlikheid. Die tesis argumenteer dat die opbou van kennis in hierdie gebiede deur wetenskaplikes (miskien teenintuïtief) gelei het tot die skepping van die toerisme-bedryf, wat nie in staat sou gewees het om te floreer sonder die konstante menslike teenwoordigheid, wat deur die wetenskaplike basisse versprei oor die Antarktieka verskaf is nie. Ten slotte, bied hierdie tesis 'n vorm van ń etnografiese historiese ondersoek in die vorm van ń binnestaander / buitestaander teenstelling (tussen "wetenskaplike" en "toeris"), waar wetenskaplikes en ondersteunings personeel as binnestaanders, en toeriste, as buitestaanders beskou word.

The trophodynamics of the numerically dominant mesozooplankton (200-2000 m) in the vicinity of the Subtropical Convergence (STC) in the Indian sector of the Southern Ocean during austral autumn (April / May) 2007 were investigated as part of the Southern Ocean Ecosystem Variability Study. The survey consisted of six north-south transects each bisecting the STC between 38º to 43ºS and 38º to 41º45’E. In total, 48 stations situated at 30 nautical mile intervals were occupied over a period of ten days. Hydrographic data revealed a well defined surface and sub-surface expression of the STC, which appeared to meander considerably between 41ºS and 41º15’S. Surface chlorophyll-a (chla) concentrations were low, ranging between 0.08 and 0.68 mg chl-a.m-3 and were generally dominated by the picophytoplankton (<2 m) which made up 66.6% (SD±17.6) of the total pigment. Chl-a concentrations integrated over the top 150m of the water column ranged between 11.97 and 40.07 mg chl-a.m-2 and showed no significant spatial patterns (p>0.05). Total integrated mesozooplankton abundance and biomass during the study ranged between 3934.9 and 308521.4 ind.m-2 (mean = 47198.19; SD±62411.4 ind.m-2) and between 239.8 and 4614.3 mg Dwt.m-2 (mean = 1338.58; SD ±1060.5), respectively. Again, there were no significant spatial patterns in the total mesozooplankton abundance or biomass within the region of study (p>0.05). No significant correlations were found between biological (chlorophyll-a concentrations and zooplankton abundance) and physico-chemical variables (temperature and salinity) (p>0.05). The total mesozooplankton community was numerically dominated by copepods of the genera Pleuromamma, Calanus, Oncaea and Oithona. Other important representatives of the mesozooplankton community included the tunicate, Salpa thompsoni, and the pteropod, Limacina retroversa. At the 40% similarity level, numerical analysis identified five distinct mesozooplankton groupings within the survey area. Differences between the groupings were associated with changes in the relative contribution of numerically dominant species rather than the presence or absence of individual species. No groupings were associated with any specific feature of the front within the survey area. The feeding rates of the six most numerically abundant mesozooplankton species (Calanus simillimus, Limacina retroversa, Pleuromamma abdominalis, Clausocalanus breviceps, Oncaea conifera, Salpa thompsoni) accounting for on average 39% of the total mesozooplankton counts, were investigated using the gut fluorescence technique. For all species, the total gut pigment contents during the night time were significantly higher than the daytime values (p<0.05 for all species). The gut evacuation rates (k) for selected mesozooplankton ranged between 0.14 and 0.81 h-1. The ingestion rates ranged between 147.8 and 5495.4 ng(pigm)ind-1.day-1 which corresponded to a daily ration of between 2.4 and 10.9% body carbon. The combined grazing impact of the selected species on the daily phytoplankton standing stock was highly variable and ranged between 1.2 and 174.1% with an average of 27.3% (SD±38.78%) within the survey area. The highest grazing impact (>60%) was typically associated with those stations where the pteropod, L. retroversa, and the tunicate, S. thompsoni, contributed more than 5% of the total mesozooplankton counts. No significant differences were found in the grazing impact of any or all selected species situated either north, south or in the immediate vicinity of the front (p>0.05 in all cases). The lack of defined spatial patterns in the mesozooplankton abundance and community structure suggests that the STC did not act as a significant biogeographic barrier to the distribution of mesozooplankton during the study. It is presumed that the large scale mixing event caused by a storm prior to this study was responsible for the observed lack of elevated biological activity within the region of the STC.

Thesis (M.S.)--University of North Carolina at Chapel Hill, 2009.
Title from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Masters of Science in the Department of Geological Sciences." Discipline: Geology; Department/School: Geological Sciences.

Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed November 17, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 126-136).

The schooling Euphausiid, Antarctic krill (Euphausia superba) is considered a keystone species in the Southern Ocean due to its abundance, prominent role in nutrient cycling, and dependency of almost all Antarctic predatory species on this single species. It has often been postulated that polar species may be more sensitive to anthropogenic contaminants on account of their evolutionary isolation from exposure. Despite geographical isolation, anthropogenic contaminants have frequently been detected in the Southern Ocean and Antarctica biota, including, heavy metals, petroleum products, persistent organics pollutants (POPs) as well as microplastic (plastics <5 mm diameter) marine debris. This thesis examined the response of Antarctic krill exposed to two common pollutants; the POP compound para, para-Dichlorodiphenyldichloroethylene (p,p’-DDE), a metabolic by-product of the pesticide Dichlorodiphenyltrichloroethane (DDT); and polyethylene (PE) microplastics. To investigate the fate of microplastics ingested by a grazing crustacean of high dietary plasticity, commercial microplastic PE beads were offered to Antarctic krill as a proportion of their diet. Krill were exposed to either a low (20%) or high (80%) dose plastic diet for four days, after which the faecal pellets and internal body burdens were examined. Antarctic krill were found to mechanically alter ingested microplastic beads into irregular fragments and nanoplastics. The capacity for fragmentation was found to be dependent on the concentration ingested. Further, the krill displayed size dependant depuration of the altered beads. This is the first time pristine microbeads have been noted to be physically altered by ingestion. With regards to the fate of commercial PE beads ingested by Antarctic krill, it appears that larger microplastics are fragmented into pieces that are small enough to cross biological barriers after ingestion, or are egested as a mixture of irregular triturated particles. These findings suggest that the current literature, based on observations from laboratory-based feeding studies, may be oversimplifying the way in which zooplankton interact with microplastics. To investigate the uptake and depuration kinetics, bioaccumulation potential and detrimental health effects of irregular triturated microplastics Antarctic krill were exposed to commercial microplastic PE beads in a range of concentrations (10, 20, 40 and 80% plastic mixed diet). Toxicological endpoints of mortality and weight loss were both found to be non-sensitive for acute exposure in Antarctic krill. The depuration of particles large enough to be detected was found to be extremely fast, with krill eliminating 80% of their accumulated body burden in a matter of hours. Effective depuration was proposed to be the primary mechanism for mitigation of bioaccumulation and toxicity in krill, with bioaccumulation over 10 days of exposure found to be negligible. However, as uptake rates were similarly fast, and organisms in the marine environment are unlikely to experience microplastic free conditions to depurate their accumulated burden, chronic exposure over the lifetime of the organism with a continuous, yet variable, uptake and egestion is suggested to be a more likely scenario. Further, particles small enough to cross biological barriers were not quantified in this study, and the bioaccumulation potential of these particles remains to be evaluated. To investigate sublethal p,p’-DDE exposure and identify potential biomarkers of sub cellular damage Antarctic krill were aqueously exposed to five treatments (1, 5, 10, 15 and 20 μg L-1) of p,p’-DDE. The response of enzymes with known roles in exogenous compound metabolism (glutathione S-transferase, GST and cytochrome P450 2B, CYP2B), neurotoxicity (acetylcholinesterase, AChE) and oxidative stress (glutathione peroxidase GPx) were quantified. CYP2B was not detectable in Antarctic krill. None of the enzymes detected induced linear concentration-dependant responses. GST was elevated at all exposure concentrations compared to the control, however no treatments were significantly different. GPx and GST followed similar trends throughout the treatment responses suggesting that an underlying biological factor may be influencing both enzymes. AChE activity was not correlated with p,p’-DDE exposure concentration, but all concentrations displayed lower activity than the solvent control however no treatment was significantly inhibited by p,p’-DDE in Antarctic krill. These findings did not provide evidence for an activated detoxification response to p,p’-DDE via the targeted biochemical pathways in Antarctic krill. These findings provide an important baseline for future work to establish the mechanisms of organochlorine toxicity and further our understanding of Antarctic krill detoxification capabilities. Overall, the results of the work described in this thesis characterise several key interactions between anthropogenic pollutants and Antarctic krill. This work provides a comprehensive foundation for further investigation on the combined effect of p,p’-DDE and polyethylene microplastic stressors, as well as other microplastics and POPs in isolation and as mixtures, which may better reflect environmental conditions.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

The metagenomic approach to gene discovery circumvents conventional gene and gene product acquisition by exploiting the uncultured majority of microorganisms in the environment. It was demonstrated in this study that metagenomic methods are suitable for gene mining in extreme environments that harbor very high levels of unculturable microorganisms. DNA was extracted from Antarctic mineral soil samples taken from the Miers Valley, Antarctica. The metagenomic DNA was also used to construct a fosmid library comprising over 7900 clones with an average insert size of 29 kb. PCR amplification using bacterial and archaeal 16S rRNA gene specific primers and subsequent denaturing gradient gel electrophoresis (DGGE) of bacterial 16S rDNA amplicons showed that a small percentage of bacterial diversity (>
1%) was captured in the metagenomic fosmid library. Activity-based screening for lipase and esterase genes using a tributyrin plate assay yielded twelve positive clones. LD1, a putative, novel cold-active GDSL lipase/esterase was identified and sequenced. The C-terminal domain of the ORF was found to be an autotransporter similar to those associated with type V secretion systems in Gram negative bacteria. Sub-cloning of the gene resulted in lipolytic activity in E. coli. Preliminary enzyme assays have determined that LD1 hydrolyses p-nitrophenyl esters with chain lengths shorter than C10, an indication that the enzyme is an esterase. Complete purification and characterisation of this enzyme is subject to further study.

Abstract Methods for tephrochronology are evaluated, in the following way: Lake sediments <500 years old from three small Antarctic lakes were analysed for identification of tephras. Subsamples were analysed for a) grain size, and identification and concentration of volcanogenic grains, b) identification of tephra horizons, c) element abundance by EPMA WDS/EDS and LA-ICP-MS, and d) possible correlations between lakes and volcanoes. Volcanogenic minerals and shards were found all through the sediment cores in all three lakes, in different abundances. A high background population of volcanogenic mineral grains, in all samples, made the identification of tephra horizons difficult, and shards could only be distinguished by certainty after chemical analysis of elements. The tephra layers commonly could not be seen by the naked eye, and, hence they are regarded as cryptotephras. Because of the small size of recent eruptions in the research area, and the travel distance of ash, most shards are small and difficult to analyse. Nine possible tephra horizons have been recorded in the three lakes, and preliminary correlations have been made. But because of analytical problems, the proposed correlations between the lakes and possible volcanic sources are preliminary.

Experience of Antarctica is unique and overwhelming and the phenomenon of the landscape and knowledge of its history continues to inspire artists and writers. Since Antarctica's discovery and exploration both before and during the Heroic Age; explorers, expeditioners, artists and writers have attempted to record and visualise Antarctica. In1982 international Antarctic programmes started to assist artists to travel to Antarctica with the intention of providing perceptive interpretations no longer attached to science or exploration. This practice-led research is the first project where a jeweller has explored and interpreted a personal experience of Antarctica to produce souvenir and jewellery objects. These objects reveal new interpretations of Antarctica that engage with the viewer through the recognisable personal jewellery and souvenir object. This research has produced new contemporary souvenir and jewellery objects by interpreting both personal photographs and re-examining the historic stories, photographs and representations of Antarctica. The bibliographic investigations of historical jewellery and souvenirs provided specific examples of historical personal mementos that are now displayed in museums. This research analyses the meaning of historical examples of souvenirs and jewellery and examines the way in which photography has been manipulated and used on hard media. Through this analysis and examination of historical examples the research focuses on studio-based experimentation with enamelling and contemporary technologies to establish the links enamelling has had with micromosaics and miniature painting. This practice-led research investigates new and innovative ways to interpret these historical techniques and draw on the notion of the souvenir. Thinking through the processes used in this research and retelling the personal experience of Antarctica, contemporary technologies are used to reimagine historical examples of tourist jewellery and personal souvenirs presenting a further understanding of Antarctica's significance both culturally and environmentally. The research not only provides an addition to the diverse range of interpretations of Antarctica it also explores the area of enamelling in contemporary jewellery and object making by contributing to the current revival of the tradition both locally and internationally. This research offers new experiences and knowledge through the investigation, experimentation, manufacture and installation of enamelled objects.

Antarctic fish from the suborder Notothenioidei inhabit what is perhaps the most thermally stable ocean environment on Earth. Evolutionary theory suggests that by specialising for this environment, Antarctic fish have traded-off their ability to respond to variations in temperature, and like their environment, have become extremely stenothermal. However, previous research has revealed that the Antarctic notothenioid fish Pagothenia borchgrevinki is not as thermally limited as evolutionary theory might predict, and is capable of acclimation to 4 ℃ during a one month period. The purpose of the current research was to investigate the physiological mechanisms that underpin this remarkable acclimatory ability. P. borchgrevinki were acclimated for one month to 4 ℃ and changes in oxygen consumption, prolonged swimming ability, cardiovascular function, enzyme activity and haematology were measured. Significant changes in resting oxygen consumption rate and prolonged swimming ability occurred during the acclimation period, and these changes were mediated by adjustments of enzyme activity and specific aspects of the haematology. By monitoring resting oxygen consumption and prolonged swimming ability over a much longer, six month, acclimation period it was confirmed that the adjustments evident during one month at 4 ℃ were sustainable in the long-term, and were not short-term compensatory mechanisms. Interestingly, fish infected with x-cell gill disease did not possess the same ability to acclimate as was demonstrated by healthy P. borchgrevinki. P. borchgrevinki are unusual among the notothenioids, possessing an active, pelagic lifestyle which differs from the sedentary, benthic lifestyle of most other species within the suborder. Therefore, it was hypothesised that the acclimatory ability demonstrated by this species may also be unusual among the notothenioids. To test this hypothesis, the acclimation ability of three sedentary, benthic notothenioids (Trematomus bernacchii, T. hansoni and T. pennellii) was investigated. Results confirmed the hypothesis, with all three species demonstrating very poor survival at 4 ℃ and absolutely no capacity for acclimation. Such results present a disturbing scenario for the future of Antarctic notothenioid fish in Earth?s rapidly warming climate, and highlights the need for continued research combined with immediate action to combat the warming which currently threatens Antarctic marine biodiversity.