Résumé
Theoretical studies suggest that connectivity plays a fundamental role in the dynamics, community structure, genetic diversity, and resiliency to human exploitation of coral reef fishes. Modeling efforts have been hindered, however, by the paucity of empirical estimates of, and processes controlling, population connectivity in coral reef ecosystems. While progress has been made with older life stages, connectivity as a function of larval dispersal remains unresolved for most marine populations. We have developed a new technique, based on transgenerational marking of embryonic otoliths with enriched barium isotopes, to quantify population connectivity in coral reef fishes. Gravid females are injected with an enriched stable Ba isotope solution that generates a unique isotope signature in the otoliths of all larvae subsequently spawned by the individual for up to 3 months after the injection. Otoliths of juvenile fish are then scanned for the tag using laser ablation inductively coupled plasma mass spectrometry. Validated in benthic and pelagic spawning fishes, the first field study using transgenerational marking has recently being completed in Kimbe Bay, on the northern coast of New Britain, Papua New Guinea. Results suggest that natal homing of larvae may be a common life history strategy in reef fishes, and thus appropriate spatial scales for management and conservation of coral reefs are likely much smaller than previously realized