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The effects of predation on the condition of soft corals Stephanie Garra1

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April Hall1 • Michael J. Kingsford1

Received: 31 December 2019 / Accepted: 7 June 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Soft corals are well known for producing toxic and unpalatable compounds to deter predation. In spite of these antipredation defences, a suite of specialised predators has coevolved to feed on soft corals. Direct quantification of this predation, however, has been minimal and the influence of predation on soft corals is yet to be investigated. In this study, the intensity and importance of predation by fishes on soft corals were evaluated across two locations using descriptive and experimental approaches. Thirty-six percent of soft coral colonies surveyed in the Palm Islands were found to have bite marks, with up to 40 bite marks observed on a single colony. Soft coral was also the major dietary component of the two fish species studied, representing up to 90% of bites taken by Chaetodon melannotus and 87% of bites by Neoglyphidodon melas, despite constituting less than 30% of the substratum. Simulated predation in manipulative experiments was found to have no clear effects on colony condition for two soft coral genera of contrasting morphology (Litophyton: branching and upright colonies, and Lobophytum: massive and lobate colonies). Both species showed a high capacity for recovery, with bites healing over the duration of the experiments and in most instances within 31 days. In contrast to the widespread assumption that predatory Topic Editor Michael Lee Berumen

Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00338-020-01967-x) contains supplementary material, which is available to authorized users. & Stephanie Garra [email protected] 1

ARC Centre of Excellence for Coral Reef Studies and College of Science and Engineering, JCU, Townsville, QLD 4811, Australia

interactions between fishes and soft corals are minimal, the results of this study indicate that predation can be intense but is not immediately important to soft coral colonies under current climatic conditions. Keywords Corallivory  Reef fishes  Soft coral  Predation

Introduction Soft corals (Order Alcyonacea) are a key component of the coral reef benthos, ranked second in abundance only to hard corals (Alderslade and Fabricius 2019). While typically constituting 2–25% of the substratum (Dinesen 1983; Fabricius and Alderslade 2001), soft corals can represent greater than 80% of benthic cover (Fabricius 1997). Despite their abundance, soft corals have been considered of low importance to reef-associated organisms, especially fishes. Lacking a protective external skeleton, soft corals rely on the production of an array of compounds that function as a chemical defence against potential predators (La Barre et al. 1986). These compounds are widespread across the Alcyonacea and highly effective: 90% of soft coral species are estimated to deter feeding by fish