A 3D perspective on sediment accumulation in algal turfs: implications of coral reef flattening

Tebbett, Sterling B., Streit, Robert P., and Bellwood, David R. (2020) A 3D perspective on sediment accumulation in algal turfs: implications of coral reef flattening. Journal of Ecology, 108 (1). pp. 70-80.

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Abstract

Globally, coral reefs are being transformed by a suite of stressors, the foremost being climate change. Increasingly, it is expected that these reconfigured reef systems will emerge with lower-complexity and will be dominated by algal turfs. Understanding this new operating space is vital if we are to maintain the services, such as fishable biomass production, that reefs provide. However, the functionality of these systems appears to depend on the nature of the algal turfs themselves, which is in-turn, intimately linked to the sediments they contain. As reefs are losing complexity, we need to understand if, and to what extent, algal turf condition and complex reef structure are connected. To address this issue we took advantage of recent developments in 3D structure-from-motion technology to examine how complexity metrics (elevation and surface angle) related to the nature of algal turfs on a heavily climate-impacted coral reef. This represents a novel application of this technology in the context of coral reef ecosystems. We found that as both elevation and surface angle decreased, the nutritional value of the epilithic algal matrix also decreased while sediment accumulation increased. Furthermore, we showed that elevated surfaces were characterized by far shorter algal turfs, and are potentially herbivory hotspots, offering fertile grounds for further exploration of herbivory dynamics at sub-metre spatial scales. Synthesis. This study yields new insights into the operating-space of future reefs, and suggests that as reefs flatten, sediment accumulation is likely to increase even if sediment inputs remain unchanged, altering algal turfs fundamentally. Maintaining key services provided by climate-transformed, low-complexity algal turf-dominated reefs of the future, will depend on managing the complex interactions between herbivory, sediments, algal turfs and reef structural complexity.

Item ID: 59359
Item Type: Article (Research - C1)
ISSN: 1365-2745
Keywords: climate change, coral reef, cumulative stressors, epilithic algal matrix, herbivory, photogrammetry, sediment, structural complexity
Copyright Information: © 2019 The Authors. © 2019 British Ecological Society.
Additional Information:

This article is available Open Access via the publisher's website.

Funders: Lizard Island Reef Research Foundation (LIRRF), Australian Research Council (ARC), Australian Government Research Training Program Scholarship
Projects and Grants: LIRRF Doctoral Fellowship, ARC Grant/ Award Number: CE140100020
Research Data: http://doi.org/10.25903/5d0ada7f84903
Date Deposited: 21 Jun 2020 19:53
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 50%
05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change @ 50%
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