MEPS 597:179-190 (2018)  -  DOI: https://doi.org/10.3354/meps12606

Mortality rates of small juvenile crown-of-thorns starfish Acanthaster planci on the Great Barrier Reef: implications for population size and larval settlement thresholds for outbreaks

John K. Keesing1,2,*, Andrew R. Halford1,3, Karina C. Hall1,4

1Australian Institute of Marine Science, PMB 3, Townsville MC, Townsville 4810, QLD, Australia
2Present address: CSIRO Oceans and Atmosphere and University of Western Australia Oceans Institute, Indian Ocean Marine Research Centre, M097, 35 Stirling Highway, Crawley, WA 6009, Australia
3Present address: Pacific Community, BP D5, Noumea, 98848, New Caledonia
4Present address: New South Wales Department of Primary Industries and Southern Cross University, National Marine Science Centre, PO Box 4321, Coffs Harbour, NSW 2450, Australia
*Corresponding author:

ABSTRACT: Crown-of-thorns starfish Acanthaster planci are a significant predator of scleractinian corals, with outbreak populations continuing to impose large-scale mortality on coral reef communities. We measured mortality rates of small post-settlement juvenile A. planci in a caging experiment on the Great Barrier Reef. Starfish 3 mm in diameter suffered mortality rates of 2.6% d-1, of which 73.0% was attributed to mobile predators. Starfish 13 mm in diameter had a lower rate of mortality of 0.82% d-1. There were no differences in mortality rates between sites, and localised effects, such as the presence of specific predators like the shrimp Hymenocera sp., affected within-site variability in mortality rates. The coral rubble habitat where the experiments were conducted had a large suite of generalist putative predators including both fish and invertebrates. The results from this and previously published studies were used to develop a model of size- and age-dependent mortality, which, when applied with the commonly accepted destructive outbreak threshold for adult A. planci of 10 ha-1 at age 2.5 yr, would require larval settlement rates of 5 m-2. Parameterising the magnitude of likely settlement rates and rates of post-settlement mortality provides a significant advance in understanding and modelling the population dynamics of this important coral predator.


KEY WORDS: Acanthaster · Predation · Mortality · Recruitment · Thresholds · Larval settlement · Coral reefs


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Cite this article as: Keesing JK, Halford AR, Hall KC (2018) Mortality rates of small juvenile crown-of-thorns starfish Acanthaster planci on the Great Barrier Reef: implications for population size and larval settlement thresholds for outbreaks. Mar Ecol Prog Ser 597:179-190. https://doi.org/10.3354/meps12606

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