The role of the reef flat in coral reef trophodynamics: past, present, and future

Bellwood, David R., Tebbett, Sterling B., Bellwood, Orpha, Mihalitsis, Michalis, Morais, Renato A., Streit, Robert P., and Fulton, Christopher J. (2018) The role of the reef flat in coral reef trophodynamics: past, present, and future. Ecology and Evolution, 8 (8). pp. 4108-4119.

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Abstract

The reef flat is one of the largest and most distinctive habitats on coral reefs, yet its role in reef trophodynamics is poorly understood. Evolutionary evidence suggests that reef flat colonization by grazing fishes was a major innovation that permitted the exploitation of new space and trophic resources. However, the reef flat is hydrodynamically challenging, subject to high predation risks and covered with sediments that inhibit feeding by grazers. To explore these opposing influences, we examine the Great Barrier Reef (GBR) as a model system. We focus on grazing herbivores that directly access algal primary productivity in the epilithic algal matrix (EAM). By assessing abundance, biomass, and potential fish productivity, we explore the potential of the reef flat to support key ecosystem processes and its ability to maintain fisheries yields. On the GBR, the reef flat is, by far, the most important habitat for turf‐grazing fishes, supporting an estimated 79% of individuals and 58% of the total biomass of grazing surgeonfishes, parrotfishes, and rabbitfishes. Approximately 59% of all (reef‐wide) turf algal productivity is removed by reef flat grazers. The flat also supports approximately 75% of all grazer biomass growth. Our results highlight the evolutionary and ecological benefits of occupying shallow‐water habitats (permitting a ninefold population increase). The acquisition of key locomotor and feeding traits has enabled fishes to access the trophic benefits of the reef flat, outweighing the costs imposed by water movement, predation, and sediments. Benthic assemblages on reefs in the future may increasingly resemble those seen on reef flats today, with low coral cover, limited topographic complexity, and extensive EAM. Reef flat grazing fishes may therefore play an increasingly important role in key ecosystem processes and in sustaining future fisheries yields.

Item ID: 53663
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: evolution, herbivory, hydrodynamics, productivity, reef fish, sediment
Copyright Information: © 2018 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC Grant CE140100020, ARC Grant DP140100122
Research Data: https://doi.org/10.4225/28/5a827b8b73b03
Date Deposited: 16 May 2018 07:44
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 100%
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