Larval dispersal and vertical migration behaviour – a simulation study for short dispersal times

Authors

  • Andreas Sundelöf,

    Corresponding author
    1.  Department of Marine Ecology, University of Gothenburg, Göteborg, Sweden
      Andreas Sundelöf, Department of Marine Ecology, University of Gothenburg, PO Box 461, SE 40530 Göteborg, Sweden; Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Box 4, 453 21 Lysekil, Sweden.
      E-mail: Andreas.Sundelof@bio.uib.no
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  • Per R. Jonsson

    1.  Department of Marine Ecology, Tjärnö Marine Biological Laboratory, Strömstad, Sweden
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  • Present address: Department of Biology, University of Bergen, PO Box 7800, N-5020 Bergen, Norway.

Andreas Sundelöf, Department of Marine Ecology, University of Gothenburg, PO Box 461, SE 40530 Göteborg, Sweden; Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Box 4, 453 21 Lysekil, Sweden.
E-mail: Andreas.Sundelof@bio.uib.no

Abstract

Current speed often varies with depth, so vertical movements of larvae are expected to have profound effects on dispersal velocity and therefore dispersal potential. Systematic behaviours are expected to have strong effects on dispersal. However, reliable information on the presence of vertical migrations in larvae is scarce, but the few well investigated empirical examples justify a detailed simulation study and an analysis of potential effects. We present a spatially explicit 3D hydrodynamic model that incorporates biological information in the form of active particles advected in a Lagrangian fashion. The set-up is designed to analyze the sensitivity of dispersal distances to variation in vertical behaviour of larvae. We simulated short (4 days) pelagic larval durations (PLDs) to determine whether behaviour might be important over short dispersal periods. We found that sinusoidal behaviours (slow vertical migration) in or out of phase with tides did not significantly change the dispersal patterns compared to those of larvae that remained at the surface. By contrast, a quadratic pattern of behaviour resulting in rapid vertical migration, in or out of phase with tides, had dramatic effects on both distance and direction of dispersal. The resulting dispersal kernels were found to be multimodal due to the interaction between tidal and meteorological components in flow. Incorporating biological information on larval migrations in Lagrangian simulation of dispersal will be important in estimates of connectivity and forecasting marine reserve networks.

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