Annick cros

Information on connectivity is becoming increasingly in demand as marine protected areas are being designed as an integral part of a network to protect marine resources at the ecosystem level. Larval dispersal and population structure, however, remain very difficult to assess. Here, we tested the predictions of a detailed oceanographic connectivity model of larval dispersal and coral recruitment within Palau and between Palau and Yap, which was developed to support the review of the existing network of marine protected areas in Palau. We used high throughput microsatellite genotyping of the coral Acropora hyacinthus to characterize population genetic structure. Pairwise F ST values between Palau and Yap (0.10), Palau and Ngulu (0.09) and Yap and Ngulu (0.09) were all significant and similar to pairwise F ST values of sites within Palau (0.02– 0.12) and within Yap (0.02–0.09) highlighting structure at island scale and indicating that recruitment may be even more localized than previously anticipated. A bottleneck test did not reveal any signs of a founder effect between Yap and Palau. Overall, the data supports the idea that recovery of A. hyacinthus in Palau did not come exclusively from a single source but most likely came from a combination of areas, including sites within Palau. In light of these results there seems to be very little connectivity around the barrier reef and management recommendation would be to increase the number or the size of MPAs within Palau.

The ongoing loss of biodiversity calls for assessing the performance of conservation strategies. In the case of marine protected areas (MPAs), a common indicator of success is the amount of biodiversity protected within them. However, there are many cases where the information for the official MPA boundary is not available, making it difficult to precisely measure the indicator. A solution to this problem is to create circular buffers around the centre location of MPAs for which boundaries are missing, equivalent in area to that reported officially for the MPA. The Coral Triangle Atlas provides the opportunity to quantify more precisely the validity of using buffers as proxies for MPA boundaries both at national and regional scales in the Coral Triangle. We used 612 existing MPA boundaries, converted them into point data at their centroids and then created circular buffers of area equal to that of the MPAs' original polygons. Errors in estimated area of protected coral reefs were used to measure the bias created by the centroid buffers. We obtained an underestimation of protected coral reef area, both at the scale of the Coral Triangle region and at a national scale when using centroid buffers, with a larger underestimation as more MPA boundary proxies were used. We found that the size of MPA does not have a significant effect on the percentage of bias when MPAs are smaller than 100 km 2 at a national level, and smaller than 1000 km 2 at a regional level. With less than 15% of the total MPAs in the CT region larger than 100 km 2 , these results suggest that using buffers at a national scale for small MPAs may be a good solution to missing boundaries and cheaper than trying to collect exact information if working at a national or multinational scale. However, for countries with large MPAs such as Indonesia, using this proxy system will tend to create a larger error. At a regional scale, such as the Coral Triangle region, an estimation of total protected coral reef using buffers as MPA boundaries proxies will produce a small underestimation, thus, producing conservative results of protected coral reef area. This study shows the importance of assessing the bias introduced by using proxies for MPA boundaries when measuring indicators of conservation target achievement for coastal and marine areas.