Combinaison de la modélisation biophysique et de marquages isotopiques pour estimer la connectivité démographique des populations marines : application à Dascyllus aruanus dans le lagon sud-ouest de Nouvelle-Calédonie

摘要

Understanding marine populations dynamics is critical to their effective management,and requires information on patterns of dispersal and connectivity that are still poorlyknown. Many marine organisms have a bipartite life history with a pelagic larvalstage that often represents the only opportunity for dispersal. In the last decade,new empirical and simulation approaches to measuring larval dispersal have beendeveloped, but results from these two different approaches have rarely been comparedin the context of a single marine system, impeding the use of larval dispersal modelsin metapopulation models supporting decision making. In this doctoral research, weused both approaches to investigate larval connectivity for a coral reef fish, Dascyllusaruanus, in the South-West Lagoon of New Caledonia. Our biophysical dispersalmodel shows that larval retention exhibits considerable temporal variability at bothlagoon and patch reef scales and periodically reaches large values despite low averagewater residence time. Artificial transgenerational marking of embryonic otoliths inthe wild also showed relatively low self-recruitment rates indicating high populationopenness at the reproductive season scale, with considerable monthly variability ofself-recruitment. Large quantitative discrepancies between simulations and empiricalresults emphasize the need to better understand processes that facilitate local retention,such as homing behavior and very small scale circulation patterns.