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Effect of sea cucumber density on the health of reef-flat sediments

Lee, Steven and Ferse, Sebastian C. A. and Ford, Amanda K. and Wild, Christian and Mangubhai, Sangeeta (2017) Effect of sea cucumber density on the health of reef-flat sediments. In: Fiji’s Sea Cucumber Fishery: Advances in Science for Improved Management. Wildlife Conservation Society, Suva, Fiji, pp. 54-61. ISBN 978-0-9820263-0-4

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Sea cucumbers are thought to play an important role in the recycling and remineralization of organic matter in reef sands through feeding and bioturbation. However, growing demand and high prices from Asian markets are driving the overexploitation of sea cucumbers globally,with little understanding of the consequences of local-scale removal from inshore coral reef ecosystems. Densities of Holothuria scabra were manipulated in enclosures in situ on a reef flat adjacent to Natuvu village, on the island of Vanua Levu, Fiji, between August 2015 and February 2016 to simulate an unfished and an overfished stock density. Two treatments were used: (i) high sea cucumber stocking density (350 g m-2); and (ii) exclusion of sea cucumbers (0g m-2). Two controls accounted for cage effects: (i) cage controls (no cage walls); and (ii) natural density (60 g m-2). Sedimentary oxygen consumption (SOC), grain size distribution, sediment porosity, and O2 penetration depth were recorded. SOC rates were consistently lower in high-density enclosures than when sea cucumbers were exclude, indicative of ‘healthy’ sediments. O2 penetration depth decreased significantly when sea cucumber removal coincided with elevated sea surface temperatures which are indicative of sediment health decline. Thus the removal of sea cucumbers reduces the efficiency of reef sediment to function as a filter system to buffer organic matter pulses, and negatively affects the function and productivity of inshore reef ecosystems

Item Type: Book Chapter
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science, Technology and Environment (FSTE) > School of Marine Studies
Depositing User: Amanda Ford
Date Deposited: 24 Feb 2021 03:53
Last Modified: 24 Feb 2021 03:53

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