Spatial patterns of seagrass dispersal and settlement

Alana Grech*, Jolan Wolter, Rob Coles, Len McKenzie, Michael Rasheed, Christopher Thomas, Michelle Waycott, Emmanuel Hanert

*Corresponding author for this work

    Research output: Contribution to journalArticle

    22 Citations (Scopus)

    Abstract

    Aim: The movement of propagules among plant populations affects their ability to replenish and recover after a disturbance. Quantitative data on recovery strategies, including the effectiveness of population connectivity, are often lacking at broad spatial and temporal scales. We use numerical modelling to predict seagrass propagule dispersal and settlement to provide an approach for circumstances where direct, or even indirect, measures of population dynamics are difficult to establish. Location: Great Barrier Reef, Australia. Methods: We used the finite-element Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM) to resolve the hydrodynamics of the central Great Barrier Reef and to simulate the dispersal of seagrass. We predicted dispersal and settlement patterns by releasing 10.6 million passive particles representing seagrass propagules at known sites of seagrass presence. We considered two fractions when modelling seagrass dispersal: floating and suspended propagules. Both fractions were modelled using 34 simulations run for a maximum of 8 weeks during the peak seagrass reproductive period, capturing variability in winds, tides and currents. Results: The ‘virtual’ seagrass propagules moved on average between 30 and 60 km, but distances of over 900 km also occurred. Most particle movement was to the north-west. The season (month) of release and source locations of the particles correlated with their dispersal distance, particularly for particles released offshore, with the complex coastal topography impeding movements close to the coast. The replenishment and recovery potential of the northernmost meadows was influenced by southern meadows. Protected north-facing bays were less likely to receive particles. Main conclusions: Our approach advances the conservation and management of marine biodiversity by predicting a key component of ecosystem resilience at a spatial scale that informs marine planning. We show a complex interaction among time, wind, water movement and topography that can guide a management response to improving replenishment and recovery after disturbance events.

    Original languageEnglish
    Pages (from-to)1150-1162
    Number of pages13
    JournalDiversity and Distributions
    Volume22
    Issue number11
    DOIs
    Publication statusPublished - 1 Nov 2016

    Keywords

    • dispersal
    • Great Barrier Reef
    • hydrodynamics
    • recovery
    • resilience
    • seagrass

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