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Understanding age-specific dispersal in fishes through hydrodynamic modelling, genetic simulations and microsatellite DNA analysis

Authors

  • OLIVER BERRY,

    1. CSIRO Wealth From Oceans National Research Flagship, and CSIRO Marine and Atmospheric Research, Private Mail Bag 5, Wembley, WA 6913, Australia
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  • PHILLIP ENGLAND,

    1. CSIRO Wealth From Oceans National Research Flagship, and CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tas. 7001, Australia
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  • ROSS J. MARRIOTT,

    1. Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Government of Western Australia, PO Box 20, North Beach, WA 6920, Australia
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  • CHRISTOPHER P. BURRIDGE,

    1. CSIRO Wealth From Oceans National Research Flagship, and CSIRO Marine and Atmospheric Research, Private Mail Bag 5, Wembley, WA 6913, Australia
    2. School of Zoology, University of Tasmania, Private Bag 5, Hobart, Tas. 7001, Australia
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  • STEPHEN J. NEWMAN

    1. Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Government of Western Australia, PO Box 20, North Beach, WA 6920, Australia
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Oliver Berry, Fax: +61 8 9333 6555; E-mail: oliver.berry@csiro.au

Abstract

Many marine species have vastly different capacities for dispersal during larval, juvenile and adult life stages, and this has the potential to complicate the identification of population boundaries and the implementation of effective management strategies such as marine protected areas. Genetic studies of population structure and dispersal rarely disentangle these differences and usually provide only lifetime-averaged information that can be considered by managers. We address this limitation by combining age-specific autocorrelation analysis of microsatellite genotypes, hydrodynamic modelling and genetic simulations to reveal changes in the extent of dispersal during the lifetime of a marine fish. We focus on an exploited coral reef species, Lethrinus nebulosus, which has a circum-tropical distribution and is a key component of a multispecies fishery in northwestern Australia. Conventional population genetic analyses revealed extensive gene flow in this species over vast distances (up to 1500 km). Yet, when realistic adult dispersal behaviours were modelled, they could not account for these observations, implying adult dispersal does not dominate gene flow. Instead, hydrodynamic modelling showed that larval L. nebulosus are likely to be transported hundreds of kilometres, easily accounting for the observed gene flow. Despite the vast scale of larval transport, juvenile L. nebulosus exhibited fine-scale genetic autocorrelation, which declined with age. This implies both larval cohesion and extremely limited juvenile dispersal prior to maturity. The multidisciplinary approach adopted in this study provides a uniquely comprehensive insight into spatial processes in this marine fish.

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