Predicting the cumulative effect of multiple disturbances on seagrass connectivity

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

*Corresponding author for this work

    Research output: Contribution to journalArticle

    9 Citations (Scopus)

    Abstract

    The rate of exchange, or connectivity, among populations effects their ability to recover after disturbance events. However, there is limited information on the extent to which populations are connected or how multiple disturbances affect connectivity, especially in coastal and marine ecosystems. We used network analysis and the outputs of a biophysical model to measure potential functional connectivity and predict the impact of multiple disturbances on seagrasses in the central Great Barrier Reef World Heritage Area (GBRWHA), Australia. The seagrass networks were densely connected, indicating that seagrasses are resilient to the random loss of meadows. Our analysis identified discrete meadows that are important sources of seagrass propagules and that serve as stepping stones connecting various different parts of the network. Several of these meadows were close to urban areas or ports and likely to be at risk from coastal development. Deep water meadows were highly connected to coastal meadows and may function as a refuge, but only for non-foundation species. We evaluated changes to the structure and functioning of the seagrass networks when one or more discrete meadows were removed due to multiple disturbance events. The scale of disturbance required to disconnect the seagrass networks into two or more components was on average >245 km, about half the length of the metapopulation. The densely connected seagrass meadows of the central GBRWHA are not limited by the supply of propagules; therefore, management should focus on improving environmental conditions that support natural seagrass recruitment and recovery processes. Our study provides a new framework for assessing the impact of global change on the connectivity and persistence of coastal and marine ecosystems. Without this knowledge, management actions, including coastal restoration, may prove unnecessary and be unsuccessful.

    Original languageEnglish
    Pages (from-to)3093-3104
    Number of pages12
    JournalGlobal Change Biology
    Volume24
    Issue number7
    DOIs
    Publication statusPublished - Jul 2018

    Keywords

    • connectivity
    • cumulative effects
    • graph theory
    • Great Barrier Reef
    • networks
    • seagrass

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