School of Geography - Theses

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End date: 2001 × Start date: 2001 × Subject: Victoria ×

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    Alternative community states in reservoirs of the Central Highlands region
    Bateson, Jane Karen ( 2001)
    The occurrence of nuisance algae within reservoirs of the Central Highlands region is a problem facing Central Highlands Water and the communities they serve. Therefore, there is a need to know how to manage this threat. Management of the causal factors contributing to the development of algal blooms within the Central Highlands region, and Victoria as a whole, has tended to focus on reducing nutrient loads into the system. However, in shallow lakes nutrient control alone is often ineffective in managing the undesirable effects of eutrophication including algal blooms. The main reason for this is thought to be due to existence of alternative clear, macrophyte-dominated and turbid, phytoplankton-dominated stable states in shallow freshwater systems. This thesis presents analyses of two field studies carried out to investigate the alternative stable states hypothesis on shallow reservoirs of the Central Highlands region. First an assessment of spatial variation in chlorophyll a, macrophyte abundance and key growth regulating variables has shown that within reservoir spatial variation that is often assumed to be insignificant, is significant. Such spatial variation can lead to different conclusions being drawn regarding the application of ecological models and processes that may have caused observed patterns. Consequently, an appreciation of the effects of scale is vital to ensure ecological models, such as the theory of alternative stable states, are applied correctly and the outcomes of field experiments are not confounded by spatial variation. Second an investigation of shallow reservoirs of the Central Highlands region revealed that the presence of macrophytes is associated with low algal biomass. Parallels were drawn between study sites and the model of phase changes of shallow lakes undergoing eutrophication (Moss et al., 1996). A majority of reservoirs were characterised as potentially being within the clear, macrophyte-dominated alternative state, either in the unique clear Phase I or transitional Phase n. However, several reservoirs of the Central Highlands region did not bear a resemblance to any of the alternative states (phases) identified in the literature. Accordingly, it can be concluded that reservoirs of the Central Highlands region may support alternative states but that phase changes used to describe communities of the Northern Hemisphere lakes need to be modified to suit Australian conditions. This study emphasises the need to adopt a holistic approach to managing the undesirable effect of eutrophication such as algal blooms. Within the Central Highlands region a holistic approach should include management of the macrophyte communities, water level manipulation and potentially biomanipulation in addition to nutrient control.
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    What is the value of a hole in the ground?: What is the value of discrete choice contingent valuation?
    Cook, Darron Manuel ( 2001)
    The inability of market price systems to reflect the social value associated with environmental conservation presents a barrier to the achievement of overall allocative efficiency. Stated preference valuation techniques such as the contingent valuation method have been found to be useful in capturing and measuring unexpressed preferences for environmental protection and enhancement. When applied correctly, these techniques can alleviate some of the most intractable market failures, such as those which involve pure public goods. This thesis explores the theoretical validity of different approaches to contingent valuation questioning through a survey of Victorian households' attitudes to the dereliction of open gold mine pits in the Victorian countryside. The methodological research involves comparison of discrete and continuous models of contingent valuation questioning, including a wide scale test of a new approach to discrete questioning, referred to as the "dissonance minimising choice" method, which seeks to correct the upward bias of yea-saying suspected in dichotomous choice studies. The results reveal a notable level of community concern about present mining practices in Victoria and a considerable willingness to pay for minesite rehabilitation. The results for the contingent valuation method indicate that survey respondents made robust and rational utility-maximimsing choices. The discrete-choice results were still significantly higher than the results for open ended study, with the performance of the dissonance mimimising choice method rather mixed in comparison with the traditional dichotomous choice approach. i