Setting Conservation Priorities – A Key Biodiversity Areas Analysis for the Seychelles Islands

Key Biodiversity Areas (KBAs) are areas identified as being important for the conservation of biodiversity due to the presence of threatened species or habitats, or particularly high levels of biodiversity. They are a useful concept for setting site conservation priorities, combining other categories such as biodiversity hotspots, Important Bird Areas and ‘ecoregions’. An analysis of the terrestrial KBAs of the Seychelles islands based on comprehensive biodiversity assessments identifies 48 sites of conservation importance. A high proportion of the land area of Seychelles is designated as protected areas, however, the KBA analysis indicates that this needs to be expanded by a further 47km 2 . The KBAs are threatened by development (6 sites), sea-level rise (13 sites) and unpredictable climate change (16 sites). Habitat degradation caused by invasive species is the most significant threat to the largest number of KBAs, affecting all 48 sites with invasive species dominating the plant communities in 15 sites. There is an urgent requirement for future conservation in Seychelles to combine effective legal protection of KBAs with large-scale habitat restoration. INTRODUCTION Setting conservation priorities has been the subject of intense discussion over the past 30 years. It is widely accepted that priorities for site selection must be established to maximise the effectiveness of limited conservation resources and to minimise biodiversity loss. However, there has been little agreement over how to undertake such prioritisation [1]. The main methods have included biodiversity hotspots [1, 2], specific areas of biological richness such as Important Bird Areas (IBA) [3] and Important Plant Areas (IPA), areas with threatened species [5] and representative ecosystems (‘ecoregions’) [6]. The concept of Key Biodiversity Areas combines all these priority setting measures, forming a single useful framework [7]. A recent analysis of the current state of biodiversity of the Seychelles islands allows KBAs to be identified for the islands using taxonomic diversity, threat ranking and the more subjective measures of IBAs and IPAs. This analysis enables comparisons between the effectiveness of the component measures in determining priorities for protection. The 115 Seychelles islands cover over a million square kilometres in the western Indian Ocean (Fig. 1), lying within the Madagascar region biodiversity hotspot. 7,200 species of animal, plant and fungi have been recorded from the islands, including several famous species such as the Aldabra giant tortoise Dipsochelys dussumieri (Gray) and the coco-de-mer palm Lodoicea maldivica (Gmel.)Pers. Endemism is comparatively high at between 50-88% for different animal groups [8-11] in general and approximately 45% for plants [12]. A large proportion of genera are endemic and there is one endemic family of tree, represented by the critically endan*Address correspondence to this author at the Nature Protection Trust of Seychelles, 133 Cherry Hinton Road, Cambridge CB1 7BX, UK; E-mail: [email protected] gered jellyfish tree Medusagyne oppositifolia Baker (Medusagynaceae) and an ancient endemic family of frogs (Sooglossidae). The great significance of the biodiversity of the Seychelles islands was first recognised by Professor John Stanley Gardiner of Cambridge University who organised and led the Percy Sladen Memorial Expedition to the Indian Ocean in 1905. The remarkable number of new species found in 1905 inspired Gardiner to organise a second expedition specifically to the Seychelles islands. The combined effort of these two expeditions remains the largest research effort to concentrate on the region. The Indian Ocean Biodiversity Assessment 2000-2005 (IOBA) marked the centenary of the Gardiner expeditions by surveying the biodiversity of the Seychelles islands [13]. This covered all 32 of the granitic islands, a range of the coral islands in the Amirantes, and Aldabra and the southern atolls. This programme assessed the diversity of all multicellular terrestrial and freshwater organisms, rather than relying on indicators. The results of this assessment are presented here as the first Key Biodiversity Areas analysis for an entire archipelago in the Western Indian Ocean region. METHODS Biodiversity Assessment The collecting methods used in the Indian Ocean Biodiversity Assessment and evaluation of the effectiveness of collecting are described elsewhere [13]. For most taxa collections are considered to provide an accurate assessment of the biodiversity of the islands. Fungi, tardigrades, nematodes and mites remain inadequately sampled, current data providing a comparative assessment rather than a full evaluation of diversity. KBA Measures KBAs have been defined on the basis of containing globally threatened species, restricted range species with small global ranges, congregatory species or biome restricted Setting Conservation Priorities The Open Conservation Biology Journal, 2008, Volume 2 45