Predicting the cumulative effect of multiple disturbances on seagrass connectivity. (16th April 2018)

• Record Type: Journal Article
• Authors: Grech, Alana; Hanert, Emmanuel; McKenzie, Len; Rasheed, Michael; Thomas, Christopher; Tol, Samantha; Wang, Mingzhu; Waycott, Michelle; Wolter, Jolan; Coles, Rob
• Is Part Of: Global change biology. Volume 24:Number 7(2018)
• Page Start: 3093
• Page End: 3104
• Publication Date: 2018-04-16
• Subjects: connectivity -- cumulative effects -- graph theory -- Great Barrier Reef -- networks -- seagrass; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.14127
• Languages: English
• ISSNs: 1354-1013

Abstract

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. Abstract : Tropical coasts are globally threatened, yet there is limited information on functional connectivity, replenishment and recovery at management relevant scales. We used network analysis and a biophysical model to measure connectivity and predict the impact of multiple disturbance events on tropical seagrasses. Our results show that seagrass networks were densely connected and resilient to the random loss of meadows by disturbance events. The scale of disturbance event required to disconnect the networks was around half the length of the seagrass metapopulation. Management actions should focus on improving environmental conditions that support natural seagrass recruitment and recovery processes.