Since the first reserve selection algorithm was developed in the early 1980s, systematic approaches to reserve design have attracted widespread support due to their ability to identify repeatable and efficient solutions to conservation planning problems. Yet there has been limited application of these methods to the problem of designing reserve systems for biodiversity conservation in the marine environment. In my dissertation research, I apply systematic methods to examine four fundamental issues in marine reserve system design. These issues consider how conservation planning outcomes are influenced when design constraints such as spatial compactness, efficiency, economic costs and incremental reserve establishment are formulated as part of the reserve design problem. First, I consider the trade-offs between spatial design and cost efficiency. In particular, I examine how well marine reserve systems can satisfy the design requirement to minimise the degree of fragmentation whilst minimising reserve system cost. In this case cost refers to the number of sites required to achieve biodiversity conservation objectives. The second issue is the inefficiency of ad hoc marine reserve system design. In terrestrial systems, ad hoc reserve design has been shown to produce inefficient reserve systems, limiting opportunities to achieve conservation targets. I examine how efficiently South Australias existing marine reserves contribute to quantitative conservation targets and introduce a new measure of irreplaceability. This metric reflects the potential value of a sites contribution to reservation goals, by assessing whether a site is selected more than could be expected from chance alone. Sites selected as often as would be expected by chance, fail to contribute to the design of efficient marine reserve systems and represent an opportunity cost. The third issue addresses the demands on reserve systems to achieve both conservation and socio-economic objectives. Options for the design of marine reserve systems, which achieve better economic outcomes for commercial users without compromising conservation targets, are examined using a cost function that serves to make tradeoffs early in the design process. The fourth issue is one of shifting targets and incremental reserve design. The problem was most recently highlighted with the rezoning of the Great Barrier Reef Marine Park, where the amount of no-take areas increased from 5% to over 30% but the original zoning arrangements were left in place. The consequence this has on the efficiency of the final marine reserve system is examined when different starting targets are used as the base. Each issue is examined by formulating planning scenarios using data for South Australias state waters as a case study. The marine reserve systems are configured using the mathematical optimisation program MARXAN to examine the complex trade-offs of conservation planning problems. The program offers the flexibility to incorporate new approaches and developing theory in marine conservation into the formal statement of the reserve design problem. The results offer some important insights for the future of marine reserve system design. These include 1) efficient representation of biodiversity is only part of the reserve design problem, with small increases in reserve system cost reported as a trade-off for more spatially compact marine reserve systems, 2) despite spanning less than 4% of South Australian state waters, the existing ad hoc marine reserves presented considerable opportunity costs that did not improve even when conservation targets were increased. Hence ad hoc reserve selection is likely to constrain effective conservation of marine biodiversity by compromising the ability to select more suitable sites, 3) integrating conservation and socio-economic objectives presents opportunities to design representative, efficient and practical marine reserve systems that minimise potential loss to commercial users with only small increases to the areal extent of the reserve system and 4) incrementally changing target levels of reservation has a minor affect on the efficiency of the final reserve system, though is likely to influence which planning units are in the final reserve system.
| Identifer | oai:union.ndltd.org:ADTP/253668 |
| Creators | Stewart, Romola Russell |
| Source Sets | Australiasian Digital Theses Program |
| Detected Language | English |
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