Interspecific variation in potential importance of planktivorous damselfishes as predators of Acanthaster sp. eggs

Cowan, Zara-Louise, Ling, Scott D., Dworjanyn, Symon A., Caballes, Ciemon F., and Pratchett, Morgan S. (2017) Interspecific variation in potential importance of planktivorous damselfishes as predators of Acanthaster sp. eggs. Coral Reefs, 36 (2). pp. 653-661.

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Abstract

Coral-eating crown-of-thorns starfish (Acanthaster sp.) often exhibit dramatic population outbreaks, suggesting that their local abundance may be relatively unchecked by predators. This may be due to high concentrations of anti-predator chemicals (saponins and plancitoxins), but the effectiveness of chemical deterrents in protecting Acanthaster sp., especially spawned eggs, from predation remains controversial. We show that planktivorous damselfishes will readily consume food pellets with low proportions (ae<currency>80%) of eggs of crown-of-thorns starfish. However, all fishes exhibited increasing rejection of food pellets with higher proportions of starfish eggs, suggesting that chemicals in eggs of crown-of-thorns starfish do deter potential predators. Interestingly, palatability thresholds varied greatly among the nine species of planktivorous fish tested. Most notably, Amblyglyphidodon curacao consumed food pellets comprising 100% starfish eggs 1.5 times more than any other fish species, and appeared largely insensitive to increases in the concentration of starfish eggs. After standardising for size, smaller fish species consumed a disproportionate amount of pellets comprising high proportions of starfish eggs, indicating that abundant small-bodied fishes could be particularly important in regulating larval abundance and settlement success of crown-of-thorns starfish. Collectively, this study shows that reef fishes vary in their tolerance to anti-predator chemicals in crown-of-thorns starfish and may represent important predators on early life-history stages.

Item ID: 50574
Item Type: Article (Refereed Research - C1)
Keywords: Acanthaster, chemical defence, coral reefs, predation, saponins
Additional Information:

A version of this publication was included as Chapter 3 of the following PhD thesis: Cowan, Zara-Louise (2017) Predation on the early life stages of the crown-of-thorns starfish (Acanthaster cf. solaris). PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

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ISSN: 1432-0975
Funders: Ian Potter Foundation (IPF), Australian Museum Lizard Island Research Station (AMLIRS), ARC Centre of Excellence for Coral Reef Studies (CECRS)
Projects and Grants: IPF/AMLIRS 50th Anniversary Commemorative Grant
Research Data: http://dx.doi.org/10.4225/28/5938bd208c120
Date Deposited: 20 Sep 2017 10:09
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 80%
96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960402 Control of Animal Pests, Diseases and Exotic Species in Coastal and Estuarine Environments @ 20%
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