Effectiveness and length of life of trans-generation marking using Barium 137

 This project has been undertaken in collaboration with IRD (Institut de Recherche pour le Développement), and aims at studying the cross-habitat connectivity of Dascyllus aruanus a reef-dwelling damselfish, through micro-chemical study of the otholiths, to be able to derive a model of population distribution.






The technique consists of injecting the parent Dascyllus with minute doses of Barium 137, which leaves a permanent chemical signature in the nucleus of the otoliths of future embryos. Once the eggs have been laid, the larvae go through a pelagic plankton stage of approximately 2 to 3 weeks before settling on the reef. An analysis of the presence of Barium 137 in the nuclei of the otoliths of juveniles collected at different distances from the reef should provide sufficient data for connectivity modelisation. However, this is a completely novel technique, never tested in the field. The role of the Aquarium is to test its efficacy and the duration of its usefulness under controlled conditions. To this end, premises have been set aside for the experiments, and 15 families of Dascyllus were raised, then marked. The first spawning was observed early in 2012. The initial assays will be done in France by the IRD teams around mid-2012.