DNA-based identification of predators of the corallivorous Crown-of-Thorns Starfish (Acanthaster cf. solaris) from fish faeces and gut contents

Kroon, Frederieke J.; Lefévre, Carine D.; Doyle, Jason; Patel, Frances; Milton, Grant; Severati, Andrea; Kenway, Matthew; Johansson, Charlotte; Schnebert, Simon; Thomas-Hall, Peter; Bonin, Mary C.; Cameron, Darren S.; Westcott, David A.

doi:10.1038/s41598-020-65136-4

Cited by 12 publications

(31 citation statements)

References 49 publications

(117 reference statements)

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“…These results, and those of previous studies, suggest that current zoning arrangements act a means of moderating the impact of an active COTS outbreak, and that its role in a COTS Control Program will be as a complementary action used to support manual control or where manual control cannot be employed. The management utility of observed zoning effects on COTS populations is also compromised by the current lack of a mechanistic understanding of how such effects actually occur; whether directly through predation by targeted fish species 46 or indirectly through cascading trophic or behavioural effects, and whether the main effects are on the pelagic or settled phase or both 34 , 47 . Determining the role of MPAs, and, in particular, the level of take of various fisheries on the GBR, on COTS densities and population outbreaks is a focus of current work.…”

Section: Resultsmentioning

confidence: 99%

Relative efficacy of three approaches to mitigate Crown-of-Thorns Starfish outbreaks on Australia’s Great Barrier Reef

Westcott

Fletcher

Kroon

et al. 2020

Sci Rep

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100

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Population outbreaks of Crown-of-Thorns Starfish (COTS; Acanthaster spp.) are a major contributor to loss of hard coral throughout the Indo-Pacific. On Australia's Great Barrier Reef (GBR), management interventions have evolved over four COTS outbreaks to include: (1) manual COTS control, (2) Marine Protected Area (MPA) zoning, and, (3) water quality improvement. Here we evaluate the contribution of these three approaches to managing population outbreaks of COTS to minimize coral loss. Strategic manual control at sites reduced COTS numbers, including larger, more fecund and damaging individuals. Sustained reduction in COTS densities and improvements in hard coral cover at a site were achieved through repeated control visits. MPAs influenced initial COTS densities but only marginally influenced final hard coral cover following COTS control. Water quality improvement programs have achieved only marginal reductions in river nutrient loads delivered to the GBR and the study region. This, a subsequent COTS outbreak, and declining coral cover across the region suggest their contributions are negligible. These findings support manual control as the most direct, and only effective, means of reducing COTS densities and improving hard coral cover currently available at a site. We provide recommendations for improving control program effectiveness with application to supporting reef resilience across the Indo-Pacific. Crown-of-Thorns Starfish (COTS; Acanthaster spp.) are among the largest and most efficient coral predators, and COTS population irruptions (often termed 'outbreaks') are a major contributor to coral loss throughout the Indo-Pacific region 1. To address increasing and elevated densities of COTS, manual control programs, mainly involving lethal injections in situ 2 or hand collections and disposal on shore 3 , have been implemented since the 1960s. By 2014 some 84 manual control programs had been conducted across the Indo-Pacific, killing or removing at least 17 million starfish at an estimated cost of US$15-44 million 1. Such programs have generally had limited success in either suppressing COTS densities or preventing coral loss 3-5. Several authors have suggested that successful manual control is unlikely with large scale or severe COTS population outbreaks 6-9. Given that single-injection methods for culling individual COTS are now close to 100% effective 10 , significant improvements in manual control programs are likely to be found in the strategic and effective deployment of in-water resources to manage COTS impacts on coral reefs 11,12. Despite this, there is little information available on the efficacy of manual COTS control programs nor on their performance relative to other measures implemented to manage population outbreaks of COTS to minimize coral loss. The Great Barrier Reef Marine Park (GBR) is one of the world's largest coral reef ecosystems and a globally recognized world heritage area. Despite its iconic status, the GBR is subject to a range of anthropogenic threats, and, like tropical coral r...

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Section: Resultsmentioning

confidence: 99%

Relative efficacy of three approaches to mitigate Crown-of-Thorns Starfish outbreaks on Australia’s Great Barrier Reef

Westcott

Fletcher

Kroon

et al. 2020

Sci Rep

Self Cite

100

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“…Cheilinus undulatus shapes benthic communities via predation on mollusks, crustaceans, and echinoids, including the crown of thorns starfish (Cowan et al, 2017;Kayal et al, 2012;Kroon et al, 2020;Randall et al, 1978), while B. muricatum is the most important bioeroder and the largest coral predator (Bellwood & Choat, 2011), holding a keystone role in the maintenance of coral community structure and stability of coral reefs (Bellwood et al, 2012). Consistent with previous studies that used underwater visual census techniques in shallow water, our study using BRUVS identified high abundances of these large iconic labrids at the Rowley Shoals and relatively low abundances at other atolls and islands (Bellwood et al, 2012;Edgar et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Isolated reefs support stable fish communities with high abundances of regionally fished species

Birt

Cure

Wilson

et al. 2021

Ecology and Evolution

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“…The predatorremoval hypothesis proposes that overfishing has released COTS from top-down control [14]. This is supported by findings that a suite of target (fished) and non-target species prey on COTS gametes, larvae, juveniles, and adults [15][16][17], and that marine protected areas which would be expected to have a more intact fish guild are less prone to outbreaks [18][19][20]. Finally, as periodic outbreaks appear to be an inherent feature of COTS, it has been hypothesised that these are also a natural phenomenon [21] and, as the larvae evolved in oligotrophic tropical waters, the larval-resilience hypothesis posits that they are naturally resilient to food limitation [22,23].…”

Section: Introductionmentioning

confidence: 96%

Diet flexibility and growth of the early herbivorous juvenile crown-of-thorns sea star, implications for its boom-bust population dynamics

et al. 2020

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The ecology of the early herbivorous juvenile stage of the crown-of-thorns sea star (COTS, Acanthaster spp.) is poorly understood, yet the success of this life stage is key to generating population outbreaks that devastate coral reefs. Crustose coralline algae (CCA) has been considered to be the main diet of herbivorous juveniles. In this study, we show that COTS can avail of a range of algal food. Juveniles were reared on CCA, Amphiroa sp., and biofilm, and survived for 10 months on all three diets. The juveniles fed CCA and Amphiroa sp. reached 15-16.5 mm diameter at~6 months and maintained this size for the rest the experiment (an additional~4 months). Juveniles fed biofilm grew more slowly and to a smaller maximum size (~3 mm diameter). However, when juveniles were switched from biofilm to CCA they resumed growth to a new asymptotic size (~13.5 mm, 13-20 months). In diet choice experiments, juveniles did not show a preference between Amphiroa sp. and CCA, but generally avoided biofilm. Our results show that juvenile COTS grew equally well on CCA and Amphiroa sp. and can subsist on biofilm for months. Some juveniles, mostly from the biofilm diet treatment, decreased in size for a time and this was followed by recovery. Flexibility in diet, growth, and prolonged maintenance of asymptotic size indicates capacity for growth plasticity in herbivorous juvenile COTS. There is potential for juvenile COTS to persist for longer than anticipated and increase in number as they wait for the opportunity to avail of coral prey. These findings complicate our ability to predict recruitment to the corallivorous stage and population outbreaks following larval settlement and the ability to understand the age structure of COTS populations.

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DNA-based identification of predators of the corallivorous Crown-of-Thorns Starfish (Acanthaster cf. solaris) from fish faeces and gut contents

Cited by 12 publications

References 49 publications

Relative efficacy of three approaches to mitigate Crown-of-Thorns Starfish outbreaks on Australia’s Great Barrier Reef

Relative efficacy of three approaches to mitigate Crown-of-Thorns Starfish outbreaks on Australia’s Great Barrier Reef

Isolated reefs support stable fish communities with high abundances of regionally fished species

Diet flexibility and growth of the early herbivorous juvenile crown-of-thorns sea star, implications for its boom-bust population dynamics

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