Dissertations / Theses on the topic 'Tasman Sea'

The relatively understudied intermediate waters of the world have been implicated as an important part of the global ocean circulation. This thesis discusses the intermediate waters of the Pacific over space and time. Initially, by using geochemical tracers to look at the present distribution, sources and mixing of the water masses. Secondly, by using oxygen and carbon isotopes from sediment cores to study changes in Antarctic Intermediate Waters (AAIW) over the late Quaternary in the north Tasman Sea. The sediment cores also provide sedimentological data on the hemipelagic sedimentation in the Capricorn Channel in the southern Great Barrier Reef as well information on changes in the East Australian surface current (EAC) over the last glacial-interglacial transition. [A more extended Abstract can be found in the files]

An advective box—model based on mass and salt conservation arguments and volume of Tasman Sea Central Water for different temperatures and salinities has been used to determine the influence of the seasonal outflow from Bass Strait on the Tasman Sea thermocline as well as to identify the regions where previously observed strong positive salinity anomalies occur. Of the total salt flux into the layer bounded by the 25.73 and 26.96 at isopycnal surface s, about 8% is supplied by the prescribed Bass Strait transport of 0.45 Sv while 34% is accounted for by downwelling from the overlying high salinity water. The highest vertical salt flux occurs in the Southern Tasman Sea somewhere between 37° and 43° S. This corresponds to the region where positive salinity anomalies were found to occur, characterized by large salinity gradients and the existence of offshore salinity maxima along isothermal and isopycnal surfaces. The distribution of the Bass Strait Water volume in the Tasman Sea displays a similar pattern suggesting that the seasonal intrusion of BSW may act as a trigger to entrain high salinity water from the upper layers by double diffusive convection. Double —diffusive arguments are also presented to explain some of the features of the intrusion of Bass Strait Water in the Tasman Sea.

Fish larvae in Australian waters have been studied progressively in the last 2-3 decades including the distribution and abundance of taxa, growth and age, their prey and predators. However, the effect of nutrient limitation on ichthyoplankton is unstudied, particularly in the oligotrophic Australian waters. My study was aimed to examine the effect of natural or anthropogenic nutrients on the abundance, distribution, growth and condition of fish larvae along-shore of the NSW coast (latitude 30-34S), where the East Australian Current departs the NSW coast and generates local upwelling of cool nutrient-rich water. This study shows no significant difference in the total abundance or diversity of either larval fishes amongst the 112 taxa (111 families and 1 order), among regions within or upstream of the upwelling. However in both months, there were distinctive ichthyoplankton assemblages at the family level. The Carangidae, Labridae, Lutjanidae, Microcanthidae, Myctophidae and Scombridae were more abundant in the EAC or oceanic water masses, while the Callionymidae, Clupeidae, Platycephalidae, Sillaginidae and Terapontidae were mostly found in the surface or deep upwelled/uplifted water masses. This pattern is observed in other ichthyoplankton studies and may be a general and useful method to determine mixing of water masses. Larvae of silver trevally (Pseudocaranx dentex) and yellowtail scad (Trachurus novaezelandiae) were generally larger and less abundant in the topographically induced upwelling region, than north of the region in pre-upwelled conditions of the East Australian Current. Both species were mostly at the preflexion stage (less than 4.3 mm in body length and less than 10 days old) in the pre-upwelled conditions, particularly during November, and proportionally more larger and older larvae in the upwelled waters (mostly post-flexion, greater than 4.3 mm in body length and greater than 10 days old). Ages from sagittal otoliths ranged from 2-25 increments (~days) and exhibited linear growth for both species and months over the size range (3-15 mm standard length). The otolith radius-length relationship and the growth rates were similar between species and months, despite the 3-4C difference between months. Overall growth rates of the younger larvae were uniform throughout the entire sampling area (0.5-0.6 mm.d-1), while older larvae grew significantly faster in the upwelled water (0.41 mm.d-1) compared to the non-upwelled conditions (0.34 mm.d-1). Both species tended to be depleted in 13C in the upwelling region (from ???18.5 to ???19.0), consistent with expected ratios from deeper water, whereas the 15N composition tended to increase in Pseudocaranx, but decrease in Trachurus indicating different diets and possibly trophic level. The early life history of both species indicates spawning in pre-upwelled waters, but larval transport into upwelled waters is necessary for faster growth in the post-flexion stage. The assemblage of larval fishes did differ between the upwelled region and a region south of Sydney???s deepwater outfalls, but the difference was ascribed to a latitudinal effect and the EAC. Both larval carangids were enriched in 15N, possibly due to the enriched dissolved organic matter of primary treated sewage. In summary, this study found that the larval fish community can provide a biological means to trace water masses, and estimate their degree of mixing. Remarkably there was no significant effect of upwelling or sewage addition to the abundance or diversity of larval fish, in the nutrient poor waters of the East Australian Current. Larval carangids and pilchards were abundant in late spring off northern NSW, and their early life histories were inferred. Both larval carangid species seem to be spawned in the EAC waters, but as post-flexion larvae grew faster in the upwelled zone. Pre-flexion (less than 10 day old) larval carangids of both genera indicated spawning in the EAC, and the rarer post-flexion (greater than 10 days old) carangids grew faster in the upwelled waters. Here, both genera had stable isotope signatures characteristic of upwelled waters for carbon, but had different nitrogen signatures, indicative of different diets and trophic level status. Larval pilchards actually grew more slowly in the upwelling region, as observed in coastal waters off Japan, and their nursery grounds may be further offshore in the Tasman Front, analogous to their early life history in the Kuroshio Extension.

Comparative phylogeography seeks to compare phylogeographic patterns of multiple co-distributed species in order to examine levels of temporal and spatial congruence. Comparative assessments can lead to reconstructions of major trends in the recent histories of dispersal of a region and can provide significant advances in understanding how behaviour, demography and natural histories of species and populations can influence phylogeographic patterns. When common spatial patterns of evolutionary sub-division are found between co-distributed species they are thought to share a biogeographic history. Although concordant phylogeographic patterns have been found across multiple taxa, not all comparative phylogeographic studies have found evidence of congruence. The influence of dispersal potential on the phylogeographic structuring of multiple co-distributed species was the main focus of this thesis. The main goal was to explore how dispersal potential, based on life history characteristics, influenced phylogeographic structure on a large-scale in multiple co-distributed species, and in particular how this influenced oceanic island populations. Whilst there are disagreements in the biogeographic literature as to whether vicariant or dispersal processes best explain the geographic distribution of a species, the colonisation and accumulation of biotic assemblages on oceanic islands is unequivocally the result of transoceanic dispersal. The biotic communities present on oceanic islands therefore inevitably consist of species that are able to disperse well. Genetic variation within island populations is directly influenced by the dispersal potential of the species in question. Species that disperse frequently will be more closely related to the source population due to continual migration to the islands from mainland (or other island) sources; whereas species that do not disperse as often will be more genetically distinct and divergent from the source population.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Marine phytoplankton account for more than 40% of global primary production and hence play an important role in moderating global climate through ocean-atmosphere CO2 exchange. Zinc (Zn) is an essential micronutrient and plays an important role in the carbon acquisition system within marine phytoplankton, thus, it has the potential to influence marine primary production. In seawater, Zn bioavailability is dependent on its concentration and its chemical speciation. The free Zn2+ ion concentration of the surface ocean is usually in the low picomolar range with the potential to be growth limiting for some phytoplankton species. The aim of this research is to better understand Zn cycling in the ocean and the relationship between primary production and Zn bioavailability by exploiting variations in the Zn isotope composition of phytoplankton and seawater samples. To realise this aim, a procedure was developed to measure the Zn isotope composition of marine samples. This procedure utilises the double spike (DS) technique in conjunction with the pre-concentration of Zn from seawater to determine processes that influence the Zn biogeochemical cycling in the ocean. Seawater samples, collected as part of a 2010 GEOTRACES process study, contrasting oligotrophic waters of north Tasman Sea and the mesotrophic waters of south Tasman Sea, were analysed using this technique. In this study, variability in δ66Zn of dissolved Zn is observed in the upper ocean (0-200 m) for the mesotrophic waters and is attributed to biological activity of eukaryotic phytoplankton. At stations where eukaryotic phytoplankton dominated, heavier δ66Zn values coincided with the chlorophyll maxima suggesting preferential uptake of lighter Zn isotopes by phytoplankton. To complement the field work, a Tasman Sea isolate of the coccolithophore Emiliania huxleyi was cultured across a range of free Zn2+ ion concentrations to determine the extent of Zn isotope fractionation during Zn uptake. The laboratory results support the field observation that the resident phytoplankton community controls δ66Zn composition of the upper water column in the south Tasman Sea. The intermediate and deep waters of the south Tasman Sea have Southern Ocean origin. The Southern Ocean plays a significant role in the global carbon cycle influencing both ocean circulation and biogeochemistry. Much of the surface waters of the Southern Ocean have low iron (Fe) bioavailability. I investigated the role Fe limitation plays in Zn accumulation and Zn isotope fractionation by the Southern Ocean haptophyte Phaeocystis antarctica, a major component of the Southern Ocean phytoplankton assemblage. Under Fe-limiting condition an increased cellular quota for Zn (expressed as Zn:P) and heavier δ66Zn values within the cells is observed; Whereas, cells grown under Fe-replete conditions have a lower Zn quota and a lighter δ66Zn composition. Thus, Fe bioavailability could regulate the dissolved Zn isotope composition of the Southern Ocean, which in turn would be reflected in other parts of the world ocean. This study highlights the importance of carefully analysing phytoplankton community structure and the trace metal composition while interpreting δ66Zn composition of the biologically active upper water column of the ocean.

The increasing threat of C02 to the global warming has prompted many governments to implement strategies to reduce the emission of C02 and other greenhouse gases into the atmosphere. The sequestering of C02 collected from power stations into the ocean is one of the promising strategies which can be used to achieve this goal. The east coast of Australia is identified as a favourable location for the C02 dumping scheme. The location of power stations along the east coast, with its narrow continental shelf, has provided favourable conditions for both the economical construction and running costs, of the ocean C02 disposal scheme. Compared to other oceans in the world, the Tasman Sea, and South Pacific Ocean in general, because of its high concentration of carbonate ions in the water column and sedimentary CaCO3, provides one of the best regions in which neutralisation of C02 can take place. The uncertainties of the fate of C02 after it has been released into the ocean and of its environmental impact are investigated. The current knowledge of C02 dumping schemes are reviewed to identify the most suitable scheme that can be adopted for Australia. It is proposed that an injection of liquid C02 at a depth of 1,000 m would be sufficient to ensure the long-term aim of sequestering the C02 produced in Australia into the ocean as well as minimising the environmental impact to the marine environment. A special release nozzle is needed to allow maximum mixing between the liquid C02 and seawater. The creation of denser COz-enriched plume will allow the anthropogenic C02 collected to sink to greater depths. The aims of creating the sinking current are two. One is to ensure the C02 reaches a greater depth and thus increases the resident time of C02 in the ocean. The other is to allow the C02 to react with sediment CaCO3, which in general is in abundance in the Tasman Sea and the South Pacific Ocean. This neutralisation process will not only reduce the impact of C02 on the environment but also provide a permanent sequestration of C02.

Dissertação para obtenção do Grau de Mestre em Conservação e Restauro, Especialização em Ciências da Conservação
Com o surgimento do piano a par de uma alteração dos gostos musicais da época, após o século XVIII o cravo caiu em desuso. Apenas oito cravos atribuídos a Pascal Taskin (1723-1793)sobreviveram até aos nossos dias, sendo o que pertence ao Museu da Música de Lisboa alvo de grande especulação. Embora este instrumento se encontre catalogado como um grand ravalement de um prestigiado cravo flamengo de Andreas Ruckers, foi apontado como falso Ruckers por Grant O’Brien. Devido à sua história e importância, desde 2006 este instrumento encontra-se classificado como tesouro nacional. Este estudo pretende compreender a autenticidade do ravalement através da caracterização material da policromia exterior do cravo, recorrendo a análises não destrutivas, não invasivas e in situ como reflectografia de infravermelho e espectrometria de fluorescência de raios X dispersiva de energias; e análises micro-destrutivas como microscopia óptica, microscopia electrónica de varrimento com espectrometria de raios X por energias dispersivas, micro-difracção de raios X, micro-espectroscopia de infravermelho com transformada de Fourier, pirólise seguida de cromatografia gasosa acoplada à espectrometria de massa e identificação de madeiras. Através do desenvolvimento de uma metodologia de trabalho adaptada, pode afirmar-se que o cravo em estudo tem pelo menos cinco intervenções. Estas intervenções não se encontram sistematicamente em todos os motivos, pelo que se podem entender como refrescamentos de alguns motivos decorativos de acordo com os gostos da época (diferentes figuras podem ter diferentes números de policromias e policromias de diferentes períodos de tempo). No que diz respeito à autenticidade do ravalement, pode concluir-se que embora se trate de um falso Ruckers, estamos perante um cravo sujeito a um autêntico ravalement.

This thesis is an exploration of ancestral narratives in the fiction of Thomas Keneally and Christopher Koch. Initially, ancestry in literature creates an historical relationship which articulates the link between the past and the present. In this sense ancestry functions as a type of cultural memory where various issues of inheritance can be negotiated. However, the real value of ancestral narratives lies in their power to aid in the construction of both personal and communal identities. They have the potential to transform these identities, to transgress “natural” boundaries and to reshape conventional identities in the light of historical experience. For Keneally, ancestral narratives depict national forbears who “narrate the nation” into being. His earlier fictions present ancestors of the nation within a mythic and symbolic framework to outline Australian national identity. This identity is static, oppositional, and characterized by the delineation of boundaries which set nations apart from one another. However, Keneally’s more recent work transforms this conventional construction of national identity. It depicts an Irish-Australian diasporic identity which is hyphenated and transgressive: it transcends the conventional notion of nations as separate entities pitted against one another. In this way Keneally’s ancestral narratives enact the potential for transforming identity through ancestral narrative. On the other hand, Koch’s work is primarily concerned with the intergenerational trauma causes by losing or forgetting one’s ancestral narrative. His novels are concerned with male gender identity and the fragmentation which characterizes a self-destructive idea of maleness. While Keneally’s characters recover their lost ancestries in an effort to reshape their idea of what it is to be Australian, Koch’s main protagonist lives in ignorance of his ancestor’s life. He is thus unable to take the opportunity to transform his masculinity due to the pervasive cultural amnesia surrounding his family history and its role in Tasmania’s past. While Keneally and Koch depict different outcomes in their fictional ancestral narratives they are both deeply concerned with the potential to transform national and gender identities through ancestry.

Sustainable fishing is required to protect and maintain marine biodiversity and to ensure fisheries that are both economically viable and productive. Effective management of living marine resources requires well-informed decisions through an appreciation of past, present and future pressures. Understanding “why fish are caught where they are?” is the oldest question in fisheries research and is a central issue for the sustainable catch, management and conservation of marine resources. Here we look at the Australian longline fishery to better understand where yellowfin tuna (Thunnus albacares) are caught on the hooks set by the eastern tuna and billfish fishery (ETBF) in the Tasman Sea. We view the catch of this species in the context of the recent oceanography of the Tasman Sea, sixty years of fishermen‟s knowledge and experience, a future climate scenario, declining stocks of other large pelagic predatory fish and an increasing demand in products derived from these species. The physical environment directly influences the distribution, abundance, physiology and phenology of marine species. Relating species presence to physical ocean characteristics to determine habitat associations is fundamental to the management of marine species, however, direct observation of highly mobile animals in the open ocean, such as tunas and billfish, is challenging and expensive. As a result detailed data on habitat preferences using electronic tags has only been collected for the large iconic, valuable or endangered species. An alternative is to use commercial fishery catch data matched with historical ocean data to infer habitat associations. Using catch information from an Australian longline fishery and Bayesian hierarchical models we investigate the influence of environmental variables on the catch distribution of yellowfin tuna (Chapter 2). The focus was to understand the relative importance of space, time and ocean conditions on the catch of this pelagic predator. We found that pelagic regions with elevated eddy kinetic energy, a shallow surface mixed layer and relatively high concentrations of chlorophyll a are all associated with high yellowfin tuna catch in the Tasman Sea. Time and space information, while important, were less informative than oceanic variables in explaining catch. An inspection of model prediction errors identified clumping of errors at margins of ocean features, such as eddies and frontal features, which indicate that these models could be improved by including representations of dynamic ocean processes which affect the catch of yellowfin tuna. We use the same catch prediction model to consider where yellow fin tuna catches may occur in the context of a future climate scenario (Chapter 3). We used output from a global climate model (GCM) from the IPCC 2007 AR4 summit to produce predictions of surface ocean characteristics for the Tasman Sea in the 2060s. These data were used to initialize a biogeochemical model to create an ocean productivity product for the surface ocean that was equivalent to the chlorophyll a concentration as estimated by the ocean color SeaWiFS product. We use these products as inputs for the YFT catch prediction model to determine where YFT may be caught in the Tasman Sea in 2060s. We compare these predictions to those from the 1990s and the 2000s to show how the pattern of modelled YFT catches differ from those estimated by the model for the earlier time periods. Identifying possible shifts in the availability of YFT to commercial longlining over such long time period inform the construction of long-term goals upon which strategies for resource management; coastal infrastructure development and fleet management can be considered. This approach can also be applied at shorter time scales if biogeochemical downscaling is available. Successful sustainable management of living marine resources can occur when the enhanced details of the resource, industry and market are thoughtfully integrated into the planning and implementation of management strategies. Engaging the fishing community in the management process is a proven approach to the successful implementation of management strategies with sustainable outcomes. We report on a 2006 survey of the ETBF which recorded the perspectives of the resource users and cooperative managers regarding the location and catch of YFT in the Tasman Sea (Chapter 4). We show that the fishing community hold varied perspectives on the most influential ocean characteristics with respect to YFT catch and show how perspectives relate to the fishing region. Further work collecting, analysing and incorporating the opinions and knowledge of the fishermen of the ETBF into habitat and catch models is recommended as a direction for future work. Utilizing the qualitative information from fishers would minimise biases in the catch information, associated with the multispecies targeting and markets prices, and encourage better collaboration between fishermen, scientists and management for the sustainable future of the resource and fishing community of the east coast of Australia. Overall, the work presented here show that YFT catches in the Tasman Sea can be partially explained by variation in the surface ocean environment. To achieve this goal, we used machine learning techniques to identify the most informative variables from the available ocean data and used a generalized linear model based on a hierarchical Bayesian framework to characterise the relationship between these variables and YFT catch. These techniques have not previously been used for this purpose in the Tasman Sea. The algorithms and model structures employed here provide a valid alternative to conventional habitat modelling techniques.

Zinc (Zn) plays an essential role in metabolic and structural functions for marine phytoplankton, being required in nearly 300 enzymes and proteins including carbonic anhydrase and alkaline phosphatase. The concentration of total dissolved Zn in the open-ocean is typically in the nanomolar (0.1-10 nmol L\(^{-1}\)) range, 98 % of which is complexed by natural strong organic ligands. In January and February 2010, the Primary productivity Induced by Iron and Nitrogen in the Tasman Sea (PINTS) cruise covered a north to south transect from the oligotropic Tasman Sea to the productive waters of the subantarctic Southern Ocean. For this thesis, samples for chemical analyses and laboratory- based cultures were collected to assess the relationship between phytoplankton growth and zinc bioavailability and speciation in this region. The pennate diatom \(Nitzschia\) \(closterium\) and the coccolithophorid \(Emiliania\) \(huxleyi\) were cultured at low free Zn concentrations ([Zn\(^{2+}\)] = 1.5 x 10\(^{-12}\) M and [Zn2+] = 1.5 x 10\(^{-14}\) M) to mimic the range of free Zn encountered in marine systems. Both species were able to maintain their photosynthetic activity and growth at the low [Zn\(^{2+}\)] applied. However, while E. huxleyi grew at these low concentrations, \(N. closterium\) seemed to accelerate its uptake with specific and efficient transporters and access complexed Zn. In the Tasman Sea, total dissolved Zn was observed at 0.02 to 0.19 nmol L\(^{-1}\) (at 15 m depth) and 0.02 to 0.11 nmol L\(^{-1}\) (at 150 m) along the north-south transect studied, below the range reported for other open-ocean regions. Measurements with Anodic Stripping Voltammetry (ASV) on four selected profiles from the Tasman Sea established the concentrations of labile Zn (0.6 to 500 pmol L\(^{-1}\)) and Zn-complexing ligands (0.23 to 4.19 nmol L\(^{-1}\)) for the first time in the Tasman Sea. Zn speciation was dominated by complexation to organic ligands (59 to 98%) with the highest percentages in surface. These ligands were closely related to the phytoplankton assemblages found in the studied region (Chlorophytes ~ Haptophytes > Diatoms). The links between chemistry and biology were studied with a simple conceptual ZnPPZZD model. It was parameterised with information gained in the experimental phases of this work, such as the difference of uptake response observed for the two species and range of concentrations measured. The model showed the concentration of ligands and zinc speciation played an important role in the structure of the conceptual phytoplankton assemblages. Further work is required to assess if ligands are produced by the organisms to enhance their uptake or if the chemistry of Zn strongly influences the community for a specific region.

The relatively understudied intermediate waters of the world have been implicated as an important part of the global ocean circulation. This thesis discusses the intermediate waters of the Pacific over space and time. Initially, by using geochemical tracers to look at the present distribution, sources and mixing of the water masses. Secondly, by using oxygen and carbon isotopes from sediment cores to study changes in Antarctic Intermediate Waters (AAIW) over the late Quaternary in the north Tasman Sea. ¶ The geochemical tracers highlight the presence of three separate intermediate water masses in the Pacific: North Pacific Intermediate Water (NPIW), AAIW and Equatorial Intermediate Water (EqIW). The EqIW has previously been considered an extension of intermediate water masses to the north or south. The unique geochemical characteristics of EqIW indicate, however, that it cannot be formed by direct mixing of the NPIW and AAIW. Geochemical tracers suggest instead that EqIW must also include mixing with nutrient rich, oxygen deficient, old Pacific Deep Water (PDW). ...

Eddies play a critical role in the distribution of heat and other properties in the oceans. They are most intense in regions of western boundary currents, where the kinetic energy associated with eddies is one order of magnitude greater than the kinetic energy associated with the mean flow. The East Australian Current (EAC) is the western boundary current of the South Pacific Ocean. Its flow and related mesoscale variability extend through the Tasman Sea - a region characterised by high variability associated with a complex field of eddies. Here, the path of long-lived anticyclonic eddies originating in the EAC is explored. In addition, the evolution of their properties and dynamics over time is also investigated, with a focus on their vertical velocity. These eddies are studied in fields from a free-running ocean model, from a data-assimilating ocean model, and from gridded satellite altimetry. In this thesis, I choose to examine case studies of eddies. This approach contrasts to most recent studies of eddies that tend to undertake statistical analyses of a large number of eddies. Moreover, the eddies are manually tracked - again, in contrast to a large portion of the community who have embraced datasets generated by automatic eddy-tracking algorithms. The improved accuracy and reliability of a manual approach warrants the additional time and effort to carefully track each eddy. Analysis of anticyclonic eddies that form from the EAC indicates that such eddies can “live” for over 5 years. I find that some of these eddies leave the Tasman Sea, propagate around Tasmania, and move towards the Indian Ocean. As they propagate, their amplitude is often impacted by interactions with other eddies and with the continental slope. Additionally, the speed at which eddies propagate varies considerably - with some eddies stalling in the same latitude for up to six months. As eddies propagate out of the Tasman Sea, their circulation becomes systematically more barotropic - with deeper penetrating velocities. One of the most interesting findings of this thesis is that the vertical velocity in eddies often shows alternating upward and downward cells. Such cells have been previously reported - but were not fully explained, in terms of their dynamics. Here, a dynamical explanation for these cells is provided. Specifically, the alternating cells are shown to relate to a process referred to in this thesis as “eddy distortion”. Eddy distortion refers to the change of shape of an eddy - that is, when an eddy becomes more, or less, isotropic. This distortion can be quantified by the change of sea level anomaly (SLA) associated with the eddy in time - also seen as alternating positive and negative cells. This quantity can be linked to the eddy interior dynamics and, ultimately, vertical velocity. In a region of inward distortion of an anticyclonic eddy, the SLA decreases and the water column below the permanent pycnocline vertically stretches, generating cyclonic relative vorticity and inducing upward motion. Conversely, in a region of outward distortion, the SLA increases and the water column below the permanent pycnocline vertically squeezes, generating anticyclonic relative vorticity and inducing downward motion. I find that the alternating cells are remarkably long-lived and spatially coherent. These cells typically extend from 2000 m depth to the base of the thermocline and their magnitude are often 20-50 m/d. The alternating upward and downward cells explain 30-60% of the variance of the vertical velocity within each eddy. The vertical circulation within eddies, described here, is expected to significantly impact the distribution of ocean properties, including heat, freshwater, and marine biota. Recognition of the link between eddy distortion - quantified by the temporal change of SLA - and the vertical circulation within eddies opens the door for the development of algorithms that link sea level to ocean productivity, and other oceanographic metrics.This has not been explored here - but is an exciting topic for future work.

A small dot of land in the middle of the Tasman Sea, Lord Howe Island presents an interesting and unique opportunity to examine several archaeological and historical questions relating to the colonization of islands, settlement landscapes, and the development of isolated communities. Through a combination of historical research and archaeological investigation, this project seeks to investigate the processes of development and change that were operating in the LHI settlement landscape and to arrive at an understanding of how these processes may or may not have significance for the understanding of other island colonization events, particularly prehistoric ones. Extensive background historic research utilizing various published and unpublished sources; community consultation and gathering of local knowledge; surveys of six historically known sites and excavation of four; and the synthesis of the historic and archaeological data in the creation of settlement landscape maps and identifications of resource use over time were employed as mechanisms of understanding the processes of colonization on a Pacific island, and allowed an assessment of its usefulness as an analogue for similar historic and prehistoric scenarios. The consequential thesis that is presented here outlines these research tasks and results and culminates in the general conclusion that Lord Howe Island is both a useful example and comparative case for other studies while paradoxically being subject to its own unique historic context, and is therefore limited to useful generalities rather than specifics.

A small dot of land in the middle of the Tasman Sea, Lord Howe Island presents an interesting and unique opportunity to examine several archaeological and historical questions relating to the colonization of islands, settlement landscapes, and the development of isolated communities. Through a combination of historical research and archaeological investigation, this project seeks to investigate the processes of development and change that were operating in the LHI settlement landscape and to arrive at an understanding of how these processes may or may not have significance for the understanding of other island colonization events, particularly prehistoric ones. Extensive background historic research utilizing various published and unpublished sources; community consultation and gathering of local knowledge; surveys of six historically known sites and excavation of four; and the synthesis of the historic and archaeological data in the creation of settlement landscape maps and identifications of resource use over time were employed as mechanisms of understanding the processes of colonization on a Pacific island, and allowed an assessment of its usefulness as an analogue for similar historic and prehistoric scenarios. The consequential thesis that is presented here outlines these research tasks and results and culminates in the general conclusion that Lord Howe Island is both a useful example and comparative case for other studies while paradoxically being subject to its own unique historic context, and is therefore limited to useful generalities rather than specifics.

The interconnected nature of the oceans, the small size and passive nature of larvae has resulted in the presumption that marine populations are large and open. However, this paradigm has been challenged in the last few of decades, where genetic studies have found significant structure at very fine-scales (of the order of 10 km). Given that many sedentary marine organisms can only disperse via a larval phase, it is intuitive that the duration of this phase (pelagic larval duration, PLD) should correspond with a species dispersal capacity and hence predict population genetic structure. Furthermore, if PLD predicts dispersal capacity then PLD should correlate with a species distribution. In this thesis, the population genetic structure of three sedentary marine organisms, endemic to the south-east Australia Pacific region, was examined to explore the relationships between dispersal capacity, life-history and geographical distribution. In chapter 2 the influence of an oceanic frontal system, the Subtropical Front (STF), on the genetic structure (mitochondrial region cytochrome c oxidase subunit I), trophic status (stable isotopes δ15N and δ13C) and condition (RNA:DNA, protein:DNA, DNA:dry weight) of the benthic gastropod Fusitriton magellanicus was examined across the Chatham Rise, New Zealand. The front acted as barrier to the transport of material between flanks, such that populations of F. magellanicus from the northern flank were in poorer condition than those from the southern flank. In addition, δ15N signatures were different between flanks, the northern flank being more enriched than the southern flank, indicating that F. magellanicus on the north flank where either starving or occupying a higher trophic level. Despite the STF shaping the trophic ecology of F. magellanicus, no differences in genetic structure were found. This indicates that there is larval exchange between or around the STF and hence larval biology may override environmental factors. To explore if a limited dispersal capacity, in contrast to its PLD (~30 days), was responsible for driving the unusual and abbreviated distribution of the sea urchin Heliocidaris tuberculata, its population genetic structure was characterised in chapter 3. Examination of the genetic structure using three different genetic markers (COI, 16S and 12 microsatellites) across the geographical distribution of the species (New South Wales coast and across the Tasman Sea to Lord Howe, Norfolk and the Kermadec Islands) was made, revealing a complete absence of structure (microsatellites FST = 0.003, COI PhiPT = 0.0021, and 16S PhiPT = 0.029). To elucidate the role of other important environmental factors in shaping genetic patterns, correlations between genetic measures and key environmental variables were explored, but no significant relationships were found. Therefore, H. tuberculata is panmictic across its range and its unusual restricted latitudinal distribution, despite it wide longitudinal distribution, is not explained by a limited dispersal capacity. The population genetics of H. erythrogramma was examined across south-eastern Australia, to explore the influence of historical versus contemporary forces on the structure of a species with a short PLD (3-5 days), in chapter 4. Using two different markers (cytochrome c oxidase subunit 1 (COI) and microsatellites), the population genetic structure of H. erythrogramma was examined from New South Wales to South Australia inclusive of Victoria and Tasmania. Analysis of the COI data revealed two strong eastern and southern genetic groups, diverging across a known phylogeographical barrier, the Bassian Isthmus. Within the two genetic groups, the signature of contemporary processes was evident with the direction of migration consistent with the influence of the ocean currents on larval dispersal. A combination of contemporary oceanography, and habitat restrictions appear to maintain these signatures in the present day. Whilst PLD places some restrictions on dispersal capacity, it does not prevent an extensive geographical range and/or high levels of gene flow at extensive spatial scales. In chapter 5, it was postulated that temperature may restrict the southern range limit of H. tuberculata. Examination of the thermal tolerance of the two species revealed that the upper temperature tolerance for both species was the same, however, H. erythrogramma had a lower cold thermal tolerance than H. tuberculata. Furthermore, the temperature tolerances of both species matched sea surface temperatures that their larvae would normally encounter. Hence, an inability to tolerate cold temperatures explains why H. tuberculata has a restricted southern range limit, whereas the wider thermal envelope of H. erythrogramma ensures its distribution around temperate Australia. In summary, the thesis reveals that whilst life history considerations can shape the genetic structure of a species, oceanography and environmental considerations (e.g. temperature) can play a more important role in determining how populations are connected and species range limits.

Thesis (M.S.)--University of Wisconsin--Madison, 2003.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 37-44).

Formation of sea urchin 'barrens' has been documented widely in temperate regions of both northern and southern hemispheres. While the phenomenon has been reported worldwide, the mechanism(s) underpinning barren ground formation are poorly understood. Elucidating the mechanism(s) of barrens formation is important, not the least reason being because it may provide options for management to minimise the establishment and or spread of urchin barrens. One potential mechanism is through increases in urchin population density as a result of reduced predation mortality because of exploitation of predators. We examined whether fishing of rock lobster (Jasus edwardsii) and fish predators on rocky reefs in Tasmania could account for population increases of the sea urchin Heliocidaris erythrogramma to the point where overgrazing of macroalgae may lead to urchin barrens. Large-scale surveys (over > 100 km of coastline) of abundances of urchins and putative predators revealed a significant negative relationship between urchins and lobster abundances, but not between urchins and demersal fishes. At smaller scales, both large lobsters and demersal fish are significantly more abundant inside no-take marine reserves than in equivalent adjacent habitat subject to fishing. These observations are consistent with results of small-scale experiments in which the rate of urchin mortality was ea. 23 times greater inside two marine reserves than in adjacent exploited habitats. Caging experiments also showed that predation by rock lobsters on sea urchins is highly size-specific. Juvenile lobsters are not capable of predating urchins with test diameter (TD) > 60 mm, while medium-sized lobsters preyed on urchins up to 80 mm TD, and large urchins >81 mm TD were only at significant risk of predation mortality from large lobsters. Demersal fish were notably less important predators of urchins between 40-100 mm TD than were rock lobsters. Inside reserves, if urchins were tethered so that they could not seek shelter, then juvenile urchins were predated more frequently than larger ones. However, when tagged urchins were free to move, mortality of adult urchins was significantly higher than that of juveniles, because juveniles were able to shelter in small crevices. I also examined the possibility that higher urchin population densities on barrens could be the result of sporadic large recruitment events. In mark-recapture experiments, three distinct urchin populations were used to construct individual-based growth models to generate size-at-age relationships. Age frequency distributions of urchin populations in algal beds and adjacent barrens habitat were estimated using this relationship and examined for the presence of dominant cohorts which may indicate prominent recruitment events. Significant differences were found in the age frequency distributions of urchin populations in barren and algal bed habitats at two separate locations, with dominant peaks in the age structures of urchins in barrens populations unmatched by those in adjacent algal beds. Estimates of age-specific mortality rates and age frequency distributions derived for several distinct urchin populations enabled construction of matrix models of population growth. Using the empirical estimates of size-specific per capita rates of predation by lobsters on urchins, I estimate the effect of exploitation of lobsters in regulating urchin population density by comparing model projections for urchins based on lobster populations inside and outside marine reserves. The modelling suggests clearly that the reduction in biomass of legal-sized lobsters on the east coast of Tasmania due to fishing is sufficient to account for increases in populations of H. erythrogramma to the point where barrens formation may occur.

An understanding of past sea level change in Tasmania is essential to understanding the contribution of Antarctic ice melt to the global oceans. Research into Holocene sea level history in Tasmania has been sporadic and conflicting. The primary goal of this research was to develop precise Holocene sea level index points (SLIPs) for Tasmania, south eastern Australia, achieved by: establishing the relationship between Tasmanian coastal salt marsh biogeomorphology and mean sea level; and locating and documenting palaeo-environments that contain a Holocene sea level signal of substantial duration. The northern hemisphere quantitative, base of basal salt marsh approach was combined with the Australian coastal geomorphic landform evolution approach to reconstruct Holocene sea level history. Pleistocene transgressive surfaces in micro tidal drowned river valleys in south eastern Tasmania provided a set of depth sequenced base of basal sea level index points. A full intertidal foraminifera based transfer function was calibrated with a sediment core to fill gaps in this sea level record. A contrasting coastal evolution sedimentary record in a meso tidal, open coast intertidal setting in north western Tasmania was examined by targeting an organically enriched sedimentary deposit underlying the modern salt marsh, that was inferred to be a drowned Holocene salt marsh facies. Tasmanian salt marshes are constrained to elevations relative to MSL within sites, but inundation period is a better predictor of marsh zonation than elevation. The greatest between site variation in inundation period occurs at marsh seaward edges that are limited to no more than 33% tidal inundation period per year. This regional variation in inundation period of the seaward edge limits the suitability of regional modern analogues for transfer function based sea level reconstructions. Sea levels were below present throughout the Holocene, with a mid-Holocene highstand absent. The slow rates of sea level rise after 6000 yr BP indicate continued melt water contribution from Antarctica after 6000 yr BP to the present. The open coast site in north western Tasmania did not yield a longer Holocene sea level history. The age of the putative marsh was from ~ 37 000 yr BP to ~ 26 000 yr BP. It was a preserved, semi indurated Pleistocene swamp deposit that occupied the swales between sand dune ridges through the latter stages of glacial advance, and just prior to the last glacial maximum, when aeolian processes dominated the landscape. Integrating the sea level reconstruction for Tasmania with the accepted geochronological framework for estuarine evolution added further detail on the geomorphic evolution of coastal landforms in south eastern Australia, particularly the prevalence of the transgressive sand sheet, now shown to be present in shallow marine environments outside of estuaries. Further research to better populate the early and late Holocene sea level curve for Tasmania should focus on locating the transgressive surface in shallow subtidal, and upper intertidal locations.

Isolation and structure elucidation of secondary metabolites from two red algae, Plocamium cartilagineum and Laurencia filiformis, together with the sea hare Aplysia parvula are discussed. In addition, chemical relationships between the sea hare Aplysia parvula and the red alga Laurencia filiformis were also investigated. Some details of studies from an ascidian Polyandrocarpa lapidosa, a bryozoan Watersipora lapidosa, a bryozoan Bugula dentata and its associated nudibranch Tambje verconis, as well as a bryozoan Cribricellina ruin and its associated pycnogonid Pseudopallene ambigua were included. More over, a study of brown algae, Bellotia eriophorum, Sporochnus species and Perithalia caudata was described. Two new acyclic polyhalogenated monoterpenes, (3E,7E)-8-bromo-(2E)- chloromethylene-(5R*,6R*)-dichloro-6-methyloctadien- 1-al ( 1) and (1Z,3E,7E)-8,9- dibromo-(1Z,5R*,6R*,9)-tetrachloro-6-methyoctatriene (2), as well as two known acyclic polyhalogenated monoterpenes (3-4), were isolated and identified from the red alga Plocamium cartilagineum. The structures were established by spectroscopic techniques (\(^1\)H, \(^{13}\)C NMR, DEPT, HMQC, HMBC, COSY, NOESY experiments, and mass spectrometry). [Structural formulas not included in this metadata but are included in the PDF] One new chamigrene, 5-acetoxy-2,10-dibromo-3-chloro-7,8-epoxy-α-chamigrene (5), the known chamigrene, 2,10-dibromo-3-chloro-7-chamigrene (6), deoxyprepacifenol (7), and pacifenol (8) were isolated from both the red alga Laurencia filiformis and the sea hare Aplysia parvula. On the other hand the known purple pigment, aplysioviolin (9) and the known fimbrolide (10) were isolated only from the sea hare Aplysia parvula. The fimbrolide was previously isolated from Delisea elegans and Delisea pulchra (a synonym for Delisea fimbriata). Pentadecanal (11) and its aldol product, namely (E)-2-tridecy1-2-heptadec-2-enal (12), were only separated from the red alga Laurencia filiformis. The structure of aplysioviolin has been revised in this study and pentadecanal was separated from the red seaweed Laurencia sp. for the first time. [Structural formulas not included] Homarine (13) was isolated from the ascidian Polyandrocarpa lapidosa. The structure of homarine was confirmed by synthesis. [Structural formulas not included] Two known metabolites, 1,8-dihydroxyanthraquinone (14) and 5,7-dihydroxy- I-methoxycarbony1-6-oxo-6H-anthra[1,9-bc]thiophene (15) were separated from the bryozoan Watersipora subtorquata. [Structural formulas not included] An investigation of the bryozoan Bugula dentata and its associated nudibranch Tambje verconis showed that eight known compounds, tamjamines A (16), B (17), C (18), D (19), E (20), G (21), H (22), and J (23) were found from both the bryozoan and the nudibranch. [Structural formulas not included] 16 R=R'=R"=H 17 R=Br, R'=R"=H 18 R=H, R'=CH\(_2\)CH(CH\(_3\))\(_2\), R"=H 19 R=H, R'=CH\(_2\)CH(CH\(_3\))\(_{2'}\) R"=Br 20 R=H, R'=CH\(_2\)CH\(_{3'}\), R"=Br 21 R=Br, R'=CH\(_2\)CH\(_{3'}\), R"=H 22 R=Br, R'=CH\(_2\)CH\(_2\)CH\(_{3'}\), R"=H 23 R=Br, R'=CH\(_2\)CH(CH\(_3\))CH\(_2\)CH\(_{3'}\), R"=H A study of brown algae, Bellotia eriophorum, Sporochnus comosus, Sporochnus species and Perithalia caudata showed a variable percentage content of two known compounds (24-25), which were previously isolated from Perithalia caudata. [Structural formulas not included] A preliminary study of secondary metabolites from the bryozoan Cribricellina rufa and its associated pycnogonid Pseudopallene ambigua revealed that 13—carboline metabolites were presented in the bryozoan Cribricellina rufa and the pycnogonid Pseudopallene ambigua by gas chromatography mass spectrometry.

Amoebic gill disease (AGD) is the most significant disease of farmed sea-caged salmonids in Tasmania. The research reported here provides the first substantiated evidence for a Paramoeba species as the cause of this economically important disease. A total of 680 cultures of amoebae were prepared during an extensive sampling programme of diseased Atlantic salmon, resulting in 61 successfully purified and subcultured amoeba isolates. This library of amoebae comprised the protozoan genera Platyamoeba, Vannella, Flabellula, Heteroamoeba, Vexillifera, Acanthamoeba and Paramoeba. Fixed and frozen sections of gills from fish with AGD were immunostained with polyclonal antisera against the predominant genera associated with gills. Only Paramoeba was detected in large numbers on gill tissue and always in close association with gill hyperplasia, a characteristic pathognomonic of AGD. Antisera to Paramoeba were highly specific and did not cross react with other genera of gill-associated amoebae. Specificity of the antisera has enabled the development of a rapid and highly accurate immunofluorescent antibody test for the identification of clinical cases of AGD in farmed fish and is now the major screening tool of farmed Atlantic salmon in Tasmania. Despite evidence that Paramoeba is the cause of AGD, fulfillment of Koch's postulates could not be achieved when naive rainbow trout or Atlantic salmon were exposed to freshly isolated cultures of Paramoeba with limited laboratory passage. Infection could be established however in cohabitation trials when naive fish were exposed to fish with AGD. A sensitive enzyme linked immunosorbent assay was developed using Paramoeba isolated from fish with AGD. In a preliminary survey of several Atlantic salmon populations naturally exposed to Paramoeba, between 50-100% of fish had circulating serum antibody to Paramoeba; no antibody could be detected in gill mucus. The presence of anti-Paramoeba antibodies in the serum of fish exposed to Paramoeba and/or infected with AGD provided additional evidence for the role of Paramoeba in AGD. AGD is controlled by bathing fish in freshwater. The standard treatment regime for fish was validated by determining the rate of inactivation of Paramoeba in freshwater. In addition, 37 potential anti-amoebic compounds were screened for their amoebistatic and amoebicidal activity against Paramoeba using assays developed in this study to determine contact and growth inhibition effects. From these in vitro trials it was established that Paramoeba were totally inactivated by exposure to freshwater within 120 minutes. Hydrogen peroxide at 100ppm inactivated Paramoeba within 30 minutes as did exposure to 0.lppm ozone for four hours. Of the remaining compounds tested, 8-hydroxyquinoline, chloro-iodo-hydroxyquinoline and pyrimethamine at 30µg/ml for four hours' exposure were able to inactivate Paramoeba effectively and may have potential as medicated bath treatments for AGD. These trials also identified several chemicals able to inhibit the growth of Paramoeba at concentrations of <30µg/ml and may have potential as in-feed treatments for AGD.

Changing climate has always been a fundamental driver of sea-level change. Changes in climate over the nineteenth and twentieth centuries have produced increased global sea-level rise which is expected to lead to increased erosion and progressive recession of many soft erodible coasts. However most swell-exposed sandy beaches have not yet shown such a response because other confounding processes such as beach erosion and recovery cycles are still commonly of larger scale and prevent the emergence of a detectable sea-level rise signal in beach behaviour. This thesis tests the hypothesis that there may nonetheless be some susceptible coastal landform types that are already responding to contemporary climate change-driven sea-level rise with an observable change in behaviour, for example a switch from shoreline stability to progressive recession, or an increase of previous shoreline retreat. This study analyzed air photo and beach profile records for 35 coastal sites around Tasmania (Australia) over an approximately 70-year period to compile shoreline behaviour histories. Sites were selected from a range of geomorphic types hypothesised to be susceptible to early responses to sealevel rise. Twelve distinctive sites from four different coastal environments were analysed in some detail, with these results informing analysis of 23 other sites. For all 35 sites, a shoreline behaviour history was compiled using all suitable air photos to map shoreline position changes over time using the seaward vegetation line as a shoreline proxy. The sites include some that were known from previous work to have changed their behaviour during the air-photo period, and others whose histories were unknown at the outset. Sites influenced by local anthropogenic influences were mostly avoided, but in a few cases were used if the extent of artificial interference was clearly defined. Photogrammetric error margins were quantified for arguably the most important source of uncertainty, albeit more sophisticated uncertainty analyses are possible. Some confounding factors which might prevent an early sea-level rise signal being detectable in shoreline behaviour are minimal on the Tasmanian coast, including vertical land movement and interannual sea-level variability associated with the El Nino Southern Oscillation. Present day relative sealevel rise around Tasmania is commensurate with the global average, implying that contemporary climate change-induced sea-level rise is the dominant component of local relative sea level rise. Variability in swell wave direction is another potentially confounding factor that is also minimal on Tasmania’s western and southern coasts. Study sites included 18 swell-exposed sandy beaches such as Ocean, Hope and Roches Beaches. However in order to explore shoreline responses in the absence of the swell-driven sand transport and shoreline recovery processes that may prevent detectable early sea-level rise signals, study sites were also selected at 11 sandy and sandy-saltmarsh shorelines in swell-sheltered tidal re-entrants such as Duck Bay and Cloudy Lagoon, and at 6 sites on soft-rock (cohesive clay) shorelines at Rokeby Beach and the Barilla shore in Pittwater estuary. All the sites are readily erodible and are expected to eventually recede in response to climate change-induced sea-level rise. Of the 35 study sites, 10 exhibited a change of long-term shoreline behaviour over the air photo period. Sites showing a change from stability to long-term progressive recession include swellexposed Ocean and Roches Beaches, with Nebraska and Prion Beaches showing similar but more recently emerging changes. A significant long-term increase of prior recession was found at several swell-sheltered sites at West Duck Bay and a swell-sheltered soft-rock shoreline at Barilla (Pittwater). The geomorphic and oceanographic conditions at each site were identified to frame multiple hypotheses allowing assessment of whether an early response to rising sea-levels provides the best explanation for the observed changes, or whether other plausible explanations were available. Sea-level rise and increasing onshore wind speeds emerged as the only identified drivers able to account for the observed changes at 8 of the 10 sites showing significant change. Both drivers are expected to result in storm waves more frequently running further landwards over deeper water and impacting higher on the shore profile, leading to increased shoreline erosion and recession. Both processes could drive such change at six of these sites, whereas sea-level rise is the only plausible driver identified at two sites (Roches Beach and South Barilla). At the other two sites (Stephens Bay South and Gordon), variability in sand supply and artificial interference are more likely to have driven the observed changes. The 8 study sites exhibiting long term shoreline behaviour changes consistent with sea-level rise and/or increases in onshore wind speeds were in all cases characterised by (1) the presence of an active sediment sink capable of permanently sequestering increasing quantities of eroded sediment as shoreline erosion increases in response to more frequent higher wave attack, and (2) by a persistent (commonly unidirectional) sediment transport pathway capable of efficiently delivering eroded sediment to the sink with little or no return to the eroded shore. These two inter-related conditions exist for some but not all sandy swell-exposed beaches but are common (via differing mechanisms) for soft-rock coasts and for sandy shores within tidal swell-sheltered coastal re-entrants such as estuaries and lagoons. For swell-exposed sandy beaches where these critical conditions are present, the rapid permanent loss of eroded and mobile sand minimizes the effect of cross-shore and alongshore sediment exchanges that might otherwise prevent an early sea-level rise signal in shoreline behaviour, and instead allow a “tipping-point” style of switch from stability to recession to occur. A range of other site conditions may also contribute to changing shoreline behaviour in certain process environments but are not always associated with long-term changes. However, a relatively high degree of local wind-wave exposure and fetch were found to also be critical conditions for changing shoreline behaviour within swell-sheltered tidal re-entrants such as Duck Bay, Cloudy Lagoon and Pittwater. Of the 25 (out of 35) studied shorelines which have not yet shown any detectable long-term change of behaviour over the study period, 21 do not exhibit the critical conditions of having persistent sediment transport to sufficiently large active sediment sinks (e.g., Hope Beach, Cloudy Bay Beaches East and West), or in the case of swell-sheltered re-entrants these sites have only relatively limited wind-wave exposure and fetch. However, another four swell-exposed sandy beach sites did not exhibit any longterm behaviour change despite having the critical conditions of significant active sand sinks and persistent active sand transport pathways from the study shore to active sand sinks. In each of these cases, an actively gaining sand supply equal to or larger than the amount being permanently lost from increased erosion is inferred to be the key factor preventing an early change of behaviour by compensating for increasing sand losses attributable to climate change-induced drivers of shoreline change (e.g., at Mulcahy Bay Beach and Adventure Bay South Beach). The range of differing site conditions and differing historic shoreline behaviours investigated in this study support the expectation that some coastal landform types will respond earlier than others to climate change-induced drivers including contemporary sea-level rise and increasing onshore winds. This study identifies some critical conditions differentiating early from late responders to coastal climate change-driven processes. This will improve capacity to plan adaptation to coastal climate change impacts by identifying shores susceptible to earlier changes under a continuing warming climate.

Environmental issues are increasingly a global concern and have expanded in scale, scope and complexity. Informed policy decisions can mitigate or avoid environmental problems, but this requires effective integration of science into policy. This thesis examines factors which affect the integration of science into policy and ways to improve this process. The methodology included an extensive consideration of the literature, three case studies (sea level rise managed by Clarence City Council, the Derwent Estuary Program and the Shack Sites Project), an internet survey and key informant interviews. The results indicate that the factors identified in the literature as affecting the integration of science into policy can be divided into two categories according to their influence in practice. Some of the factors (communication, recognition of constraints and respect for scientific information) were perceived to affect the integration of science into policy. However, other factors (role of scientists, timeframes and presentation of relevant information) were not perceived to affect the incorporation of science into policy in practice. The results also indicated that the most effective way to improve the process would be to increase face-to-face interactions between scientists and policymakers. Intermediaries were also shown to improve the integration of science into policy in many cases.

In Tasmania, arrival of the long-spined sea urchin (Centrostephanus rodgersii) has presented economic opportunity along with ecological change where they occur. Over the last half century, C. rodgersii has undergone climate driven range-extension and is now distributed along the entire east coast of Tasmania. The highest densities of C. rodgersii occur in northern Tasmania around the St Helens region and become less abundant along latitudinal gradients. This pattern of distribution has resulted in a developing fishery for C. rodgersii being mostly focused between ‘The Gardens’ and ‘St Helens Island’ in the north east of Tasmania where catch rates are greatest. However, a lack of definitive information on the specific drivers of roe quality has been a significant hurdle to progress of the fishery in Tasmania and mainland Australia as a whole. This species is frequently implicated with high proportions of poor quality roe in commercial catches which has deterred interest from prospective entrants to the fishery. Identifying key parameters around high quality roe will help commercial fishers and processors target individual sea urchins with a greater probability of harvesting high quality roe hereby increasing economic return with the ultimate aim of maximising the potential of this new resource. This thesis explores the biological and environmental drivers of roe quality to determine factors that indicate high quality roe. Samples of Centrostephanus rodgersii were collected monthly from St Helens kelp and barrens habitats over an 18 month period spanning May 2014 to October 2015 and assessed for roe quality. Seasonal changes in reproductive biology were determined and assessed for effect on roe quality which comprised; colour, texture, granularity and quality index (possible score of 1-5 where 1 is the lowest score attainable and 5 is the highest, quality index was the sum of all individual criteria and ranged from 3-15). Examination of gonad histology showed a distinct annual pattern in reproduction and the highest levels of roe quality were recorded in the months prior to peak gametogenesis and spawning (i.e. during March, April, May and June of 2014 and 2015). Logistic regression showed high roe quality to be significantly affected by the proportion of nutritive phagocytes (NP’s) within the gonad lumen (G21 = 47.864, P < 0.001) being 4.3 times more likely (95% CI = 1.647, 8.412) to encounter ‘A’ grade roe when NP’s were in high proportions. Furthermore, gender was also found to significantly affect likelihood of harvesting ‘A’ grade roe, but it was the interaction between proportions of NP’s and gender that increased the odds ratio to a highly probable 9.67 to 1 (95% CI = 1.976, 58.316) when individuals were male and contained a high proportion of NP’s. Histological samples collected over an 18 month period in St Helens from 2003-05 (before commercial harvesting began in Tasmania) was made available for comparative analysis and showed remarkable gametogenic synchrony with samples collected during 2014-15. Both study periods demonstrated clear winter/spring spawning (August/September) with a small number of individuals persisting through to October/November. Spawning assays (response to KCl injection) were also conducted on separate sea urchins and indicated that the magnitude of spawning response was proportional to the density of NP’s. This methodological procedure may be useful as a proxy measure of roe quality for industry (i.e. signal the end of the annual high quality period) considering high quality roe is significantly affected by the presence of NP’s. To this end, the decadal consistency in the seasonal gametogenic cycle and the relationship between ‘A’ grade roe and NP’s clearly demonstrates a temporally consistent harvest window which is critical knowledge for further development of this fishery. In addition, a suite of independent variables (exogenous and endogenous) were assessed for their effect on roe quality criteria using an ordinal logistic regression approach. Models were developed based on variables that could be; used in planning harvest operations, directly observed during harvest operations, manipulated post harvest or optimised through repeated harvesting. It was found that the independent variables; habitat, seasonality, age and test diameter (shell width) had the most influence on roe quality. Odds ratios (OR) for high quality roe were highest between April and June (OR 7.85 95% CI 4.97, 10.36) for seasonality and for sea urchins aged between 7-20yrs (OR 14.34 95%CI 9.67, 28.46). Odds ratios for sea urchins harvested from kelp habitats were also significantly increased (OR 4.78 95% CI 1.99, 4.87). The magnitude of odds ratios (particularly age) indicate that large improvements in roe quality are possible by tailoring harvest operations to accommodate these specific parameters.

The order Alcyonacea Lamouroux, 1816 (Octocorallia: Anthozoa: Cnidaria) is a species-rich group comprising soft corals and sea fans, also known as gorgonians. Alcyonaceans are perennial, long-lived and can inhabit up to 70% of coastal reef habitats. Despite this, alcyonacean taxonomy is poorly resolved, and substantial knowledge gaps remain in regards to the biology, ecology and responses to environmental change of species within this taxon. Alcyonaceans occur in all oceans of the world; however, few studies have examined temperate assemblages. Although alcyonaceans have been observed and collected from the Tamar River estuary, northern Tasmania, virtually nothing is known about these species. This study examined colony and sclerite morphology, and variation in the mitochondrial marker, mtMutS, to describe the alcyonaceans of the Tamar River estuary and their relationships with previously described species. In addition, variation in the distribution and abundance of alcyonaceans and the wider rocky reef community structure was determined among six depth categories and five sites in the lower Tamar River estuary, using photoquadrats. In total, nine alcyonacean species were described from the Tamar River estuary, including two novel genera and six novel species, along with one species (Drifa gaboensis) which represents a first record for Tasmanian waters. Although exhibiting a large range of morphological variation, these novel genera and species can be distinguished from previously described taxa on the basis of colony and sclerite morphology, and, in some cases, mtMutS sequences. The benthic survey revealed the highest abundance and diversity of alcyonaceans at Fish Beacon, the most marine site closest to the estuary mouth, where alcyonaceans comprised up to 14% cover of the benthic assemblage. Moreover, rocky reef community structure varied with depth and longitudinal distance from the mouth of the estuary. This study has established detailed baseline knowledge of the Tamar River estuary alcyonacean assemblage and rocky reef communities that is important for ongoing monitoring and informing future management of this unique estuary.

Qualitative and observational techniques and a hermeneutic methodology were employed in this project. The primary focus was to explore the institutional culture surrounding the development of the Seal Relocation programme and attendant techniques for the mitigation of seal interactions with salmon farms in south-eastern Tasmania. The methodology relied on an inductive, inquiring logic, and produced a broad picture of bureaucratic and political culture in Tasmania that reflected currents of thinking surrounding the nature of late modernity. Foucault and Pusey proved useful in understanding power and resistance and Bauman was valuable for his insight into the fractured identity of the modern organisational actor. Four sub-themes emerged: history, efficacy, ethics and politics, providing four vantage points from which to view the multiple rationalities of the actors involved. It was found that the dominant ideology of development colours environmental management in a disciplined Public Service and polity captured by the technologies of governmentality. There are, however, pockets of resistance.