Daily feeding rates of Pacific crown-of-thorns starfish (Acanthaster cf. solaris) vary with body size and coral cover across the Great Barrier Reef

Abstract

The ecological effects of high densities of crown-of-thorns starfish (CoTS, Acanthaster spp.) are driven by their cumulative feeding pressure on coral assemblages, making accurate predictions of feeding impacts essential for management. Despite this, a limited understanding of the spatiotemporal dynamics of feeding behaviour, and the environmental and biological drivers underlying them constrains our capacity to predict feeding impacts. We quantified daily feeding rates for 565 individual Western Pacific CoTS ( Acanthaster cf. solaris ) across a broad gradient of environmental conditions and population densities on Australia’s Great Barrier Reef (GBR). CoTS body size and local coral cover emerged as the strongest predictors of daily feeding rates, whilst population density, season, and water temperature had no significant effect. Notably, large CoTS (> 40 cm) at high coral cover sites consumed over ten times more coral tissue compared to smaller individuals (15–25 cm) at low coral cover sites, with mean daily consumption rates of 221.99 and 18.86 cm 2 (planar area), respectively. These estimates of daily feeding are aggregated across all different coral genera consumed. We present estimates of daily feeding rates for different size classes and coral cover that are directly compatible with existing monitoring methodologies used on the GBR, providing ecologically relevant parameters to improve outbreak impact modelling and enable more accurate forecasting of coral loss for targeted CoTS control on the GBR.

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