Tebbett, Sterling B., Faul, Sasha I., and Bellwood, David R. (2024) Quantum of fear: Herbivore grazing rates not affected by reef shark presence. Marine Environmental Research, 196. 106442.

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Abstract

Grazing by nominally herbivorous fishes is widely recognised as a critical ecosystem function on coral reefs. However, several studies have suggested that herbivory is reduced in the presence of predators, especially sharks. Nevertheless, the effects of shark presence on grazing, under natural settings, remains poorly resolved. Using ∼200 h of video footage, we quantify the extent of direct disturbance by reef sharks on grazing fishes. Contrary to expectations, grazing rate was not significantly suppressed due to sharks, with fishes resuming feeding in as little as 4 s after sharks passed. Based on our observations, we estimate that an average m2 area of reef at our study locations would be subjected to ∼5 s of acute shark disturbance during daylight hours. It appears the short-term impact of reef shark presence has a negligible effect on herbivore grazing rates, with the variable nature of grazing under natural conditions overwhelming any fear effects.

Item ID:	86017
Item Type:	Article (Research - C1)
ISSN:	1879-0291
Copyright Information:	© 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Date Deposited:	01 Jul 2025 04:32
FoR Codes:	31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 100%
SEO Codes:	28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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