Evidence of Resilience in Reef Islands in Response to Rising Sea Level on Huvadhoo Atoll, Maldives

Yiqing Liang, Paul S. Kench, Murray R. Ford, Holly East

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Reef islands are at the forefront of concern for future accelerating sea-level rise since their low-lying and isolated nature puts them at higher risk of marine inundation compared to continental coastlines. However, the perceived threat of complete submersion as implied by projected future sea-level rise and current island elevations do not consider the morphologically resilient nature of reef island systems. In particular, the role of sediment supply in the resilience of these islands is still relatively poorly studied. This study presents detailed descriptions of the sedimentary characteristics and stratigraphy of two lagoonal platform islands in Huvadhoo Atoll, Maldives, that formed during periods of Holocene sea-level rise. Island subsurface stratigraphy was reconstructed by analysing the skeletal composition and textural properties of 306 sediment samples from 37 cores extracted across the islands. Island sediments were dominated by coral sands with varied proportions of secondary constituents (molluscs, Halimeda, foraminifera, and crustose coralline algae). Downcore variations in composition show that the proportion of coral sands decrease with depth and the proportion of molluscs and Halimeda increase with depth (with the exception of cores that terminated on lagoon infill). The increased proportion of Halimeda and molluscs in these early island deposits may have resulted from the catch-up growth strategy of the reef during the mid-Holocene highstand as both organisms have high turnover rates and directly contribute to sediment production after death. The sedimentological response of increased Halimeda and molluscs highlights the resilient and dynamic nature of reef islands and the ability of reefs to adjust ecologically to changing sea levels.
Original languageEnglish
Title of host publicationProceedings of Virtual Conference on Coastal Engineering, 2020
EditorsPatrick Lynett
PublisherCoastal Engineering Research Council
Number of pages8
Volume36v
ISBN (Electronic)9780989661157
DOIs
Publication statusPublished - 31 Dec 2020
EventInternational Conference on Coastal Engineering - Online
Duration: 6 Oct 20209 Oct 2020

Publication series

NameCoastal Engineering Proceedings

Conference

ConferenceInternational Conference on Coastal Engineering
Abbreviated titleICCE
Period6/10/209/10/20

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