C onnectivity o f the coral A cro p o ra tenuis in the Spermonde Archipelago Demierbe Thibaud, Rosa Maria van der Ven, Puspitaningasih S utrisnoand Mare Kochzius D epartm ent o f Marine Biology Vrije U niversiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium E-mail: tdem ierb@ vub.ac.be Coral reefs are the marine ecosystem w ith the highest bio dive rsity o f marine species. Herm atypic corals are im p o rta n t ecosystem engineers, providing the three-dim ensional structure o f the habitat. The d istrib u tio n o f coral reefs is patchy at local scale (among islands) and large scale (across oceans). Since the adults o f coral reef taxa are sedentary, co nn ectivity among populations is only possible by dispersal o f planktonic early life h istory stages. Due to anthropogenic im pacts coral reefs are declining on a global scale and marine protected areas (MPAs) are an im p o rta n t to o l fo r th e ir conservation. However, due to the patchy nature o f the habitat MPAs should be arranged in netw orks th a t ensure connectivity among them . This w ill safeguard resilience o f these m etapopulations by providing new recruits fo r re-colonisation o f disturbed areas. Insight in the ecology and population dynamics can be used to develop m anagem ent and restoration strategies. This study w ill investigate connectivity o f the broadcasting herm atypic coral A cro po ra tenuis on tw o d iffe re n t spatial scales. C onnectivity on a local scale w ill be investigated in Spermonde Archipelago (Indonesia) w ith a m axim um distance among populations o f about 80km . A large scale analysis across the Indian Ocean w ill be conducted between populations fro m Indonesia and populations fro m East Africa. The genetic population structure w ill be investigated by utilising m icrosatellites. Analysis is based on length polym orphism in Single Sequence Repeats (SSR) o f n on ­ coding DNA regions th a t show a high m utation rate. Sixteen m icrosatellite markers were selected from literature and are tested fo r polym orphism . The selected m arkers w ill be used in a m u ltip le x PCR and the length o f the am plicons w ill be measured by capillary electrophoresis. DNA frag m en t length data w ill be scored w ith the software Genemarker and analysed w ith the program m es Genealex, FSTAT and STRUCTURE (cluster analysis). The statistical analysis o f the length data w ill allow us to measure gene flo w and to estim ate connectivity. - 47 -