Spatial patterns of seagrass dispersal and settlement

Grech, Alana, Wolter, Jolan, Coles, Rob, McKenzie, Len, Rasheed, Michael, Thomas, Christopher, Waycott, Michelle, and Hanert, Emmanuel (2016) Spatial patterns of seagrass dispersal and settlement. Diversity and Distributions, 22 (11). pp. 1150-1162.

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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.

Item ID: 46326
Item Type: Article (Refereed Research - C1)
Keywords: Great Barrier Reef, hydrodynamics, recovery, resilience, seagrass
Additional Information:

Supporting material includes 32 animations showing the dispersal of 'virtual' seagrass propagules for discrete habitat units 3,16,24 and 29 (Figure 2) at four start dates. Word document included in archive lists file names and details.

ISSN: 1472-4642
Funders: Macquarie University, James Cook University, Ian Potter Foundation, Sea World Research and Rescue Foundation (SWR), Wallonie-Bruxelles International
Projects and Grants: SWR/6/15
Date Deposited: 14 Nov 2016 04:03
FoR Codes: 06 BIOLOGICAL SCIENCES > 0607 Plant Biology > 060799 Plant Biology not elsewhere classified @ 50%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050102 Ecosystem Function @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 100%
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