Socotra

Benefits of Terapon jarbua life history strategy and consequences on its population connectivity, inferred from otolith microchemistry and microsatellite DNA

In marine fish species, dispersal or migrations are known to be the principal forces responsible to minimise population structure. Anadromous species show distinct genetical patterns linked to their specific reproductive behaviour, however little is known about catadromous species that use estuaries and freshwater as nurseries and which are thought to form panmictic population at a larger geographical scale. Nevertheless patterns of estuarine or freshwater habitat use, larval homing behaviour and site fidelity are thought to have the potential to separate populations or subpopulations. The goal of the present research project is to gain an insight into and deeper understanding of Terapon jarbua ecology and life history strategy and to test the hypothesis that its life history strategy promotes genetic separation at a smaller scale that what can be expected from a catadromous species. In island populations of Terapon jarbua specific patterns of connectivity between hyposaline and marine stages during its life cycle will be used to establish “strains” that are linked to distinct nursery habitats, as inferred from otolith microchemistry. Genetically significant differentiation between strains from different nursery habitats, tested by microsatellite DNA variability, will corroborate the identity of the strains determined by otolith microchemistry, and thus be conclusive towards the verification of the research hypothesis. The simultaneous and complementary use on the same individuals of otolith microchemistry and microsatellite DNA constitutes a new approach that has neither been utilised in this combination nor in the region to date. It will provide unique corroborative information on fish population in a complex biogeographic context.

Keywords: connectivity, life history strategy, microsatellite, otolith microchemistry, Socotra, Terapon jarbua