Kim Friedman

Use of Habitats as Surrogates of Biodiversity for Efficient Coral Reef Conservation Planning in Pacific Ocean Islands

Marine protected areas (MPAs) have been highlighted as a means toward effective conservation of coral reefs. New strategies are required to more effectively select MPA locations and increase the pace of their implementation. Many criteria exist to design MPA networks, but generally, it is recommended that networks conserve a diversity of species selected for, among other attributes, their representativeness, rarity, or endemicity. Because knowledge of species spatial distribution remains scarce, efficient surrogates are urgently needed. We used five different levels of habitat maps and six spatial scales of analysis to identify under which circumstances habitat data used to design MPA networks for Wallis Island provided better representation of species than random choice alone. Protected-area site selections were derived from a rarity-complementarity algorithm. Habitat surrogacy was tested for commercial fish species, all fish species, commercially harvested invertebrates, corals, and algae species. Efficiency of habitat surrogacy varied by species group, type of habitat map, and spatial scale of analysis. Maps with the highest habitat thematic complexity provided better surrogates than simpler maps and were more robust to changes in spatial scales. Surrogates were most efficient for commercial fishes, corals, and algae but not for commercial invertebrates. Conversely, other measurements of species-habitat associations, such as richness congruence and composition similarities provided weak results. We provide, in part, a habitat-mapping methodology for designation of MPAs for Pacific Ocean islands that are characterized by habitat zonations similar to Wallis. Given the increasing availability and affordability of space-borne imagery to map habitats, our approach could appreciably facilitate and improve current approaches to coral reef conservation and enhance MPA implementation.

First observation of the giant clam Tridacna squamosa in French Polynesia : a species range extension

The most widespread species of giant clam, Tridacna maxima, was believed to be the only giant clam species occurring in French Polynesia (Laurent et al. 2002). In mid 2006, while surveying T. maxima in Tubuai Island (Australes archipelago, French Polynesia, 23 20¢S, 145 20¢W, Gilbert et al. 2006), the larger fluted giant clam, Tridacna squamosa was identified (Fig. 1b). The specimen pictured, and several others, were found on the outer slope of the barrier reef at depths of approximately 20 m. Further genetic analysis, based on the sequencing 431 bp of 16S mtDNA confirmed the morphological identification after comparison with samples in Genebank. This result enlarges the geographical range of T. squamosa to between Polynesia (145 W) and East Africa (Rosewater 1965). Other recent observations made on high latitude islands of French Polynesia (Galzin et al. 2006) have changed the previous biogeographic patterns described for different taxa. This new occurrence confirms the potential importance of anti-tropical zones in the dispersal of species throughout the Pacific Ocean (Randall 1995). We suggest that several species may have colonised the remote eastern islands in the Pacific though high latitude islands like the Australes, before colonizing more tropical areas.