82 resultados para Estuaries - Victoria, Western

em Deakin Research Online - Australia


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Various physical, biological and chemical attributes were investigated for the Fitzroy and Merri River estuaries. This research found algal communities were most influenced by high nitrogen concentrations at times of low flow. Mangement of nutrients within each catchment is therefore of high importance to reduce the possibility of future blooms.

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Fish communities in the shallow flooded margins of an intermittently open estuary were examined over an 18 month period. A distinct shift in the fish assemblage occurred when the mouth of the estuary closed and was associated with changes in the hydro-period, food availability and physico-chemical changes in the main channel.

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This thesis addresses the physical aspects of farming on soldier settlement blocks in south west Victoria. The undeveloped land, high establishment costs, stock losses through animal diseases and lack of managerial skills all contributed to the settlers' inability to meet their financial commitments. These factors are analysed, as are the effects of declining rural commodities prices during the 1920s and 1930s. In addition, the relationship between the settlers and the successive administrative agencies is examined. The scheme was administered by the Closer Settlement Board from its inception until 1932 and much of the discussion during this period concerns the interaction between settler and inspector. Soldier settlement after World War One represented one of the last attempts to create a large body of 'yeoman' farmers. From the early 1920s there was an increasing dichotomy between the 'yeoman' and the 'managerial' ideologies. This dichotomy placed additional pressure on soldier settlers who were expected to be 'efficient' without adequate finances. In the post C.S.B. era, the focus shifts to the attempts by the Closer Settlement Commission to salvage the scheme and its greater understanding of the problems faced by the settlers. While this part of the thesis necessarily becomes more political, the physical and financial environment in which the soldier settlers worked was still an important factor in their success or failure. Unlike the C.S.B. which tended to blame soldier settlers for their situation, the Commission acknowledged that settlers' ability to succeed was often constrained by circumstances beyond their control. Under the latter administration, instalments were written off, additional land was allocated and finally the blocks were revalued to guarantee the men at least some equity in their farms. Those settlers who had survived until these changes were instituted received a 'successful outcome of their life's work'.

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Over a three-year period, impacts of changed flow regimes in small western-Victorian estuaries with Mediterranean climates were investigated. Ecosystems with artificially increased and reduced freshwater inflows were compared using a whole-system, process-based approach. Studies on such systms are rare despite their vulnerability and ecological importance.

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The meiofauna of a mangrove forest in the River Barwon estuary was studied by means of surveys and field experiments. Distinctive assemblages of meiofauna were described from the sediment and pneumatophores of the ecosystem. Fine resolution of phytal habitats was demonstrated, and particular assemblages of meiofauna were characteristic within habitat provided by dominant epibionts. Distribution of the meiofauna within leaf litter revealed high turnover rates of nematodes, and some factors controlling detrital assemblages were assessed. The vertical profile of sedimentary meiofauna was examined, and changes in abundance were related to the tychopelagic habit of many taxa at high tide. Dispersal within the water column was confirmed by pelagic trapping, and colonisation of mimic pneumatophores was investigated. The amount of algal cover, effects of grazing by gastropods, and rugosity of the colonised surface were shown to influence meiofauna colonisation of mimic pneumatophores. Establishment and persistence of patchy distributions of meiofauna at scales of less than 10 m in an intertidal environment was demonstrated, and it was concluded that this was due to the dynamic nature of assemblages rather than their integrity.

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Southern Australia is currently divided into three marine biogeographical provinces based on faunal distributions and physical parameters. These regions indicate eastern and western distributions, with an overlap occurring in the Bass Strait in Victoria. However, studies indicate that the boundaries of these provinces vary depending on the species being examined, and in particular on the mode of development employed by that species, be they direct developers or planktonic larvae dispersers. Mitochondrial DNA sequence analysis of the surf barnacle Catomerus polymerus in southern Australia revealed an east–west phylogeographical split involving two highly divergent clades (cytochrome oxidase I 3.5 ± 0.76%, control region 6.7 ± 0.65%), with almost no geographical overlap. Spatial genetic structure was not detected within either clade, indicative of a relatively long-lived planktonic larval phase. Five microsatellite loci indicated that C. polymerus populations exhibit relatively high levels of genetic divergence, and fall into four subregions: eastern Australia, central Victoria, western Victoria and Tasmania, and South Australia. FST values between eastern Australia (from the eastern mitochondrial DNA clade) and the remaining three subregions ranged from 0.038 to 0.159, with other analyses indicating isolation by distance between the subregions of western mitochondrial origin. We suggest that the east–west division is indicative of allopatric divergence resulting from the emergence of the Bassian land-bridge during glacial maxima, preventing gene flow between these two lineages. Subsequently, contemporary ecological conditions, namely the East Australian, Leeuwin, and Zeehan currents and the geographical disjunctions at the Coorong and Ninety Mile Beach are most likely responsible for the four subregions indicated by the microsatellite data.

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Knowledge of the spatial arrangement of the seagrass distribution and biomass within the Hopkins Estuary is an essential step towards gaining an understanding of the functioning of the estuarine ecosystem. This study marks the first attempt to map seagrass distribution and model seagrass biomass and epiphyte biomass along depth gradients by the use of global positioning system (GPS) and geographical information system (GIS) technologies in the estuary. For mapping seagrass in small estuaries, ground-surveying the entire system is feasible. Three species of seagrasses, Heterozostera tasmanica (Martens ex Aschers), Zostera muelleri (Irmisch ex Aschers) and Ruppia megacarpa (Mason), were identified in the Hopkins Estuary. All beds investigated contained a mixed species relationship. Three harvest techniques were trialed in a pilot study, with the 25 × 25-cm quadrat statistically most appropriate. Biomass of seagrasses and epiphytes was found to vary significantly with depth, but not between sites. The average estimate of biomass for total seagrasses and their epiphytes in the estuary in January 2000 was 222.7 g m–2 (dry weight). Of the total biomass, 50.6% or 112.7 g m–2 (dry weight) was contributed by seagrasses and 49.4% of the biomass (110.0 g m–2) were epiphytes. Of the 50.6% of the total biomass represented by seagrasses, 39.3% (87.5 g m–2) were leaves and 11.3% (25.2 g m–2) were rhizomes. The total area of seagrasses present in the Hopkins Estuary was estimated to be 0.4 ± 0.005 km2, with the total area of the estuary estimated to be 1.6 ± 0.02 km2 (25% cover). The total standing crop of seagrasses and epiphytes in the Hopkins Estuary in January 2000 was estimated to be 102.3 ± 57 t in dry weight, 56% (56.9 ± 17 t, dry weight) seagrasses and 44% (45.4 ± 19 t, dry weight) epiphytes. Of the seagrass biomass, 39% (39.7 ± 13 t, dry weight) was contributed by leaves and 17% (17.3 ± 7 t, dry weight) by rhizomes.

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The experience of urban settlement in the Western District of Victoria suggests that the pattern of growth and decline in small towns is tied to the pattern of land use. This, in turn, is determined by the economic and technological factors which influence farm management and practices. At times, these factors have encouraged urban development and small towns have flourished. For the most part, however, these forces have not been conducive to sustaining long-term growth and prosperity and small towns, have been trapped in a cycle of growth and decline.

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The promotion of closer settlement in the Australian state of Victoria between 1898 and 1914 was viewed as a panacea to many of the problems that beset the state. The region known as the Western District of Victoria was seen as particularly suitable for the application of land re-settlement policy. The study of this region highlights several important features of the closer settlement experiment in Victoria. First, it illustrates how the basic principles of closer settlement were used to further the interests of particular groups. Second, it highlights the flaws in foundations of the Closer Settlement Act which impacted on the settlers chances of success. And thirdly it points to the disastrous implications of policy implementation that paid little attention to the geographical and economic parameters governing the outcome of farming enterprises.

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We examined the status of the Little Penguin Eudyptula minor at Middle Island on the west coast of Victoria during the species' 1999/2000 breeding season. The vegetated upper surface of the island had 292 occupied burrows at a density of 0.02/m2. Peak dusk arrival occurred in January with 502 penguins coming ashore during a one-hour period. Little Penguins at Middle Island displayed important differences in breeding ecology from penguins in other Australian colonies. Early breeding combined with heavier adult and chick weights resulted in high breeding success. However, as Middle Island is a popular destination for day visitors, during the 1999/2000 Little Penguin breeding season, tourism ·was found to cause detrimental effects, including deaths of some eggs and chicks. There are also concerns for the conservation of the Little Penguin colony as faxes or dogs may readily access the island.

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Attracting and retaining allied health professionals in rural areas is a recognised problem in both Australia and overseas. Predicted increases in health needs will require strategic actions to enhance the rural workforce and its ability to deliver the required services. A range of factors in different domains has been associated with recruitment and retention in the allied health workforce. For example, factors can be related to the nature of the work, the personal needs, or the way an organisation is led. Some factors cannot be changed (eg geographical location of extended family) whereas others can be influenced (eg education, support, management styles). Recruitment and retention of allied health professionals is a challenging problem that deserves attention in all domains and preparedness to actively change established work practices, both individually as well as collectively, in order to cater for current and predicted health needs. Changes to enhance workforce outcomes can be implemented and evaluated using a cyclic model. The Allied Health Workforce Enhancement Project of the Greater Green Triangle University Department of Rural Health (GGT UDRH) is working towards increasing the number of allied health professionals in the south west of Victoria. Based on themes identified in the literature, an interactive model is being developed that addresses recruitment and retention factors in three domains: (1) personal or individual; (2) organisation; and (3) community.