Models and frameworks that enhance systematic planning for coral reef biodiversity conservation
Keywords300803 Natural Resource Management
270702 Marine and Estuarine Ecology (incl. Marine Ichthyology)
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AbstractThe global decline of coral reef biodiversity requires rapid, efficient and practical solutions. No-take marine reserves and reserve systems and other managed marine conservation areas are currently considered one of the most effective management methods to deal with this ongoing decline. Although the effects, design, and establishment of coral reef reserves have been widely debated in the literature, few examples of systematic approaches to the design of reserve systems exist. Systematic conservation planning is a procedure to prioritise sites for their inclusion in reserve systems based on data and a set of conservation principles. For coral reefs the systematic design of reserve systems has been hampered by the lack of spatially explicit data, and the lack of practical recommendations to resource managers of how to apply new scientific findings. This thesis fills critical gaps at the interface between theory, planning, and implementation of coral reef reserve systems, and provides practical guidance to reef managers. In the first chapter, literature on marine reserves is discussed and the implications for coral reef reserves are considered. Chapter 2 discusses the lessons learned in the design and implementation of a community-based marine reserve in the Philippines. Reviewing relevant literature, a framework of ‘lessons learnt’ during the establishment of local protected areas is presented, highlighting the importance of a number of factors that are vital to the success of these reserves: (a) an island location; (b) small community population size; (c) minimal effect of land-based development; (d) application of a bottom-up approach; (e) an external facilitating institution; (f) acquisition of title; (g) use of a scientific information database; (h) stakeholder involvement; (i) the establishment of legislation; (j) community empowerment; (k) alternative livelihood schemes; (l) surveillance; (m) tangible management results; (n) continued involvement of external groups after reserve establishment, and (o) small-scale project expansion. To manage coral reef species it is important to understand the processes that influence their distribution. Chapter 3 identifies the environmental factors most influential in determining coral reef fish species distributions on a regional scale. Logistic regression models for 227 fish species related presence-absence data to four remotely determined environmental predictor variables: depth 500 m away from a reef, presence of a land-sea interface, exposure, and the distance to the nearest estuary. A novel method of evaluating model significance identified suitable models for 134 species. All four predictor variables were important for the distributions of the chosen suite of fishes. Depth was the most frequently significant variable in single variable models, and the proximity of a reef to an island was the least frequently important variable. For combinations of two predictor variables, depth and exposure as well as depth and distance from the nearest estuary were the prevalent predictors of fish distributions. Several fish species responded to the combination of the distance from an estuary and the presence of the terrestrial-marine interface, indicating that these species depend on intact coastal reef habitat, which is in decline near the main sediment-laden rivers. Significant models were predominantly developed for habitat specific species. These habitat specific species are of greater conservation concern than widespread species because of their restricted range, or because threats affect them more severely if they are selectively affecting their habitat. For this reason, species distribution modelling may be an efficient method to inform reserve design. The relevance of cross-taxon congruence to the suitability of taxa as conservation representation surrogates of coral reef biodiversity across the Indo-Pacific is tested in Chapter 4, using species lists of fishes, corals, and molluscs. Congruence is identified with a linear regression analysis of dissimilarity values. The utility of a surrogate was determined by the degree to which each taxon can represent the others in a marine reserve network using a greedy reserve selection algorithm. None of the taxonomic groups examined was capable of acting as a general conservation representation surrogate. Even a data-rich taxon like fishes could be severely under-represented in reserve systems designed based on a surrogate taxon such as corals, implying that data-deficient taxa are unlikely to be represented adequately where surrogate taxa are used for planning. Despite the high cross-taxon congruence between fishes and corals, and between corals and molluscs for some regions, cross-taxon congruence was not always a reliable indicator of conservation representation surrogacy. Consequently, in Indo-Pacific coral reef ecosystems one can only be sure that a target taxon is represented fully in a marine reserve network when data on this taxon are used to select reserve sites. The fifth chapter provides a theoretical and practical framework for incorporating ecological processes that span terrestrial, marine, and freshwater environmental realms into systematic conservation planning. Firstly the types of processes are classified as interactions that exist: a) on narrow interfaces such as inter-tidal zones; b) on broad interfaces such as mangrove swamps; c) along constrained connections such as corridors used by amphibian movements between natal ponds and adult habitat; and d) through diffuse connections like bird migrations. A framework of conservation planning approaches to promote the persistence of these types of processes and examples of how they might be implemented is developed. The framework focuses both on problem formulations consistent with existing decision support tools, such as the conservation planning software MARXAN, and on new methods. The review is aimed at a broad audience of scientists, planners, and managers and takes a practical and illustrative approach, providing examples of existing work and pointing readers to tools that are available to enhance conservation planning across realms. In the concluding chapter ideas from all chapters are synthesised. This chapter discusses how the approaches and frameworks presented here could be extended, and profitable areas for future research are suggested. Overall this thesis provides new insights, concepts, and tools that can assist reef managers and scientists struggling to minimise the loss of coral reefs.