Bio-physical determinants of sediment accumulation on an offshore coral reef: A snapshot study

Tebbett, Sterling B., Schlaefer, Jodie A., Bowden, Casey L., Collins, William P., Hemingson, Christopher R., Ling, Scott D., Morais, Juliano, Morais, Renato A., Siqueira, Alexandre C., Streit, Robert P., Swan, Sam, and Bellwood, David R. (2023) Bio-physical determinants of sediment accumulation on an offshore coral reef: A snapshot study. Science of the Total Environment, 895. 165188.

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Abstract

Sediments are found on all coral reefs around the globe. However, the amount of sediment in different reservoirs, and the rates at which sediments move between reservoirs, can shape the biological functioning of coral reefs. Unfortunately, relatively few studies have examined reef sediment dynamics, and associated bio-physical drivers, simultaneously over matching spatial and temporal scales. This has led to a partial understanding of how sediments and living reef systems are connected, especially on clear-water offshore reefs. To address this problem, four sediment reservoirs/sedimentary processes and three bio-physical drivers were quantified across seven different reef habitats/depths at Lizard Island, an exposed mid-shelf reef on the Great Barrier Reef. Even in this clear-water reef location a substantial load of suspended sediment passed over the reef; a load theoretically capable of replacing the entire standing stock of on-reef turf sediments in just 8 h. However, quantification of actual sediment deposition suggested that just 2 % of this passing sediment settled on the reef. The data also revealed marked spatial incongruence in sediment deposition (sediment trap data) and accumulation (TurfPod data) across the reef profile, with the flat and back reef emerging as key areas of both deposition and accumulation. By contrast, the shallow windward reef crest was an area of deposition but had a limited capacity for sediment accumulation. These cross-reef patterns related to wave energy and reef geomorphology, with low sediment accumulation on the ecologically important reef crest aligning with substantial wave energy. These findings reveal a disconnect between patterns of sediment deposition and accumulation on the benthos, with the ‘post-settlement’ fate of sediments dependent on local hydrodynamic conditions. From an ecological perspective, the data suggests key contextual constraints (wave energy and reef geomorphology) may predispose some reefs or reef areas to high-load turf sediment regimes.

Item ID: 79462
Item Type: Article (Research - C1)
ISSN: 1879-1026
Keywords: Algal turf, Geo-ecological function, Parrotfish sediment reworking, Sediment trap, Sedimentation, Turbidity
Copyright Information: © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Funders: Australian Research Council (ARC), Lizard Island Research Station Ian potter Doctorial Fellowship
Projects and Grants: ARC FL190100062, ARC CE140100020, ARC FT200100949
Date Deposited: 03 Aug 2023 03:43
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 40%
37 EARTH SCIENCES > 3708 Oceanography > 370803 Physical oceanography @ 30%
37 EARTH SCIENCES > 3705 Geology > 370509 Sedimentology @ 30%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180501 Assessment and management of benthic marine ecosystems @ 50%
18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180506 Oceanic processes (excl. in the Antarctic and Southern Ocean) @ 50%
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