Variation in the strength of continental boundary currents determines continent-wide connectivity in kelp

Authors

  • Melinda A. Coleman,

    Corresponding author
    1. Center for Marine BioInnovation and School of Biological, Earth and Environmental Science, 501B Biological Sciences Bldg., University of New South Wales, NSW 2052, Australia
    2. Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia
    3. NSW Department of Environment, Climate Change and Water, Batemans Marine Park, Burrawang St, Narooma, NSW 2546, Australia
      Correspondence author. E-mail: melinda.coleman@environment.nsw.gov.au
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  • Moninya Roughan,

    1. Coastal and Regional Oceanography Laboratory, School of Mathematics and Statistics, University of New South Wales, NSW 2052, Australia
    2. Sydney Institute of Marine Science, 22 Chowder Bay Road, Mosman, NSW 2088, Australia
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  • Helen S. Macdonald,

    1. Coastal and Regional Oceanography Laboratory, School of Mathematics and Statistics, University of New South Wales, NSW 2052, Australia
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  • Sean D. Connell,

    1. Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia
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  • Bronwyn M. Gillanders,

    1. Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia
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  • Brendan P. Kelaher,

    1. NSW Department of Environment, Climate Change and Water, Batemans Marine Park, Burrawang St, Narooma, NSW 2546, Australia
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  • Peter D. Steinberg

    1. Center for Marine BioInnovation and School of Biological, Earth and Environmental Science, 501B Biological Sciences Bldg., University of New South Wales, NSW 2052, Australia
    2. Sydney Institute of Marine Science, 22 Chowder Bay Road, Mosman, NSW 2088, Australia
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Correspondence author. E-mail: melinda.coleman@environment.nsw.gov.au

Summary

1. Determining the extent to which coastal oceanographic processes facilitate connectivity of marine organisms underpins our understanding of the ecology and evolution of marine communities. Continental boundary currents are a dominant physical influence on marine connectivity, but determining their effect has proved elusive because of difficulties in achieving replication of currents within the distribution of a single species.

2. Australia provides an unparalleled opportunity to address such questions because it has three replicate boundary currents within narrow latitudinal ranges that share continentally distributed species. We tested whether the strength of continental boundary currents influences coastal connectivity of a dominant foundation species (the kelp Ecklonia radiata).

3. Variation in the strength of different boundary currents produced entirely different patterns of connectivity in kelp with high connectivity in strong currents and low connectivity in weak currents. Spatial patterns of genetic structuring were also correlated with the nature and strength of currents.

4.Synthesis. This result has global implications; continental boundary currents are key drivers of marine connectivity and give predictive ability with which to understand variable ecologies of temperate coastlines world-wide.

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