Climate change as an unexpected co-factor promoting coral eating seastar (Acanthaster planci) outbreaks

Uthicke, Sven; Logan, Murray; Liddy, Michelle; Francis, David S.; Hardy, Natasha; Lamare, Miles D.

doi:10.1038/srep08402

Cited by 98 publications

(107 citation statements)

References 56 publications

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“…Because of the ecological and economic importance of coral reefs, interest in the crown-of-thorns starfish has been increasing in an effort to discover potential mitigation avenues against them. The vast majority of research has focused on the ecology of the crown-of-thorns starfish, the dynamics of population outbreaks, life history (Henderson and Lucas 1971;Zann et al 1987;Keesing and Lucas 1992;Lamare et al 2014;Uthicke et al 2015), larval dispersal and survival (Fabricius et al 2010;Wooldridge and Brodie 2015), effective culling methods Rivera-Posada et al 2014) and, to a lesser extent, investigations into their toxicity (Lee et al 2014). However, the sensory biology of the crown-of-thorns starfish remains mostly unstudied.…”

Section: Introductionmentioning

confidence: 99%

Visual orientation by the crown-of-thorns starfish (Acanthaster planci)

et al. 2016

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Photoreception in echinoderms has been known for over 200 years, but their visual capabilities remain poorly understood. As has been reported for some asteroids, the crown-of-thorns starfish (Acanthaster planci) possess a seemingly advanced eye at the tip of each of its 7-23 arms. With such an array of eyes, the starfish can integrate a wide field of view of its surroundings. We hypothesise that, at close range, orientation and directional movements of the crown-of-thorns starfish are visually guided. In this study, the eyes and vision of A. planci were examined by means of light microscopy, electron microscopy, underwater goniometry, electroretinograms and behavioural experiments in the animals' natural habitat. We found that only animals with intact vision could orient to a nearby coral reef, whereas blinded animals, with olfaction intact, walked in random directions. The eye had peak sensitivity in the blue part (470 nm) of the visual spectrum and a narrow, horizontal visual field of approximately 100°wide and 30°high. With approximately 250 ommatidia in each adult compound eye and average interommatidial angles of 8°, crown-of-thorns starfish have the highest spatial resolution of any starfish studied to date. In addition, they have the slowest vision of all animals examined thus far, with a flicker fusion frequency of only 0.6-0.7 Hz. This may be adaptive as fast vision is not required for the detection of stationary objects such as reefs. In short, the eyes seem optimised for detecting large, dark, stationary objects contrasted against an ocean blue background. Our results show that the visual sense of the crown-of-thorns starfish is much more elaborate than has been thus far appreciated and is essential for orientation and localisation of suitable habitats.

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Section: Introductionmentioning

confidence: 99%

Visual orientation by the crown-of-thorns starfish (Acanthaster planci)

et al. 2016

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“…Observations of newly settled A. cf. solaris in the field (Yokochi and Ogura 1987;Zann et al 1987;Wilmes et al 2016), have revealed a strong and consistent association with CCA, which is expected given that newly settled starfish feed almost exclusively on coralline algae (Yamaguchi 1973;Lucas 1984;Zann et al 1987).Settlement experiments conducted under laboratory conditions (Yamaguchi 1973;Johnson et al 1991;Uthicke et al 2015b;Wolfe et al 2015a;Kamya et al 2016;Pratchett et al 2017b) reaffirm that CCA is important for inducing CoTS settlement. When examined microscopically, the surface of CCA is roughly textured -this finescale topographic complexity can provide a tactile stimulus for larvae to settle (Lucas 1974).…”

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confidence: 80%

30 Years of Research on Crown-of-thorns Starfish (1986-2016): Scientific Advances and Emerging Opportunities

Pratchett¹,

Caballes²,

Wilmes³

et al. 2017

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Abstract:Research on the coral-eating crown-of-thorns starfish (CoTS) has waxed and waned over the last few decades, mostly in accordance with the occurrence of population outbreaks at key locations, such as Australia's Great Barrier Reef. This review considers advances in our understanding of the biology and ecology of CoTS based on the latest resurgence of research interest, which culminated in this current special issue on the Biology, Ecology and Management of Crown-of-Thorns Starfish. More specifically, this review considers progress against 41 specific research questions posed in the seminal review by P. Moran 30 years ago, as well as exploring new directions for CoTS research. Despite the plethora of research on CoTS (> 1,200 research articles), there are persistent knowledge gaps that constrain effective management of outbreaks. Although directly addressing some of these questions will be extremely difficult, there have been considerable advances in understanding the biology of CoTS, if not the proximal and ultimate cause(s) of outbreaks. Moving forward, researchers need to embrace new technologies and opportunities to advance understanding of CoTS biology and behaviour, with focus given to key questions that will improve effectiveness of management to reduce the frequency and likelihood of future outbreaks, if not preventing them altogether.Keywords: Acanthaster; coral reefs, disturbance; management; population outbreaks; research priorities Peer-reviewed version available at Diversity 2017, 9, 41; doi:10.3390/d90400412 of 50 BackgroundCrown-of-thorns starfish (CoTS; Acanthaster spp., excluding A. brevispinus) are renowned for their capacity to devastate coral reef ecosystems . This is primarily because local densities of CoTS can increase from normally very low densities (<1 starfish.ha -1 ) to extremely high densities (>1,000 starfish.ha -1 ) during periodic population outbreaks (e.g. Chesher 1969). Moreover, CoTS are one of the largest and most efficient predators on scleractinian corals (Birkeland 1989). Whereas most other individual coral-feeding organisms (e.g., Chaetodon butterflyfishes, and Drupella snails) cause only localised injuries or tissue-loss (Cole et al. 2008;Rotjan and Lewis 2008), adult CoTS can kill entire corals, including relatively large colonies. High densities of CoTS will therefore, cause rapid and extensive coral depletion. In French Polynesia, for example, high densities of CoTS caused systematic coral loss around the entire circumference of the island of Moorea, killing >96% of coral between 2005(Kayal et al. 2012). More broadly, outbreaks of Acanthaster spp. are a major contributor to sustained declines in coral cover and degradation of coral reefs at many locations throughout the Indo west-Pacific (Osborne et al. 2011;Trapon et al. 2011;De'ath et al. 2012).While there has been considerable research, and a larger number of scientific articles (>940) focused on Acanthaster spp., extending back to the 1960s (Goreau 1964;Pearson and Endean 1969), research interest (and fundin...

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“…The eggs and sperm of COTS are neutrally buoyant (sperm) or nearly so (eggs), and thus their dispersion is largely dependent on hydrodynamic conditions at the time of spawning [61]. The vertical distribution of COTS larvae is unknown, but larvae are widely distributed horizontally on the GBR, and recently have been shown to be dispersed across most of the GBR during the spawning season, even at sites distant from known outbreaks [62]. This wide geographic coverage suggests that at least some embryos and larvae are likely to encounter low salinity waters from either river plumes or intense rain events, both of which have been demonstrated to reduce salinity over the GBR during the wet season [23,63,64].…”

Section: Discussionmentioning

confidence: 99%

The Effects of Salinity and pH on Fertilization, Early Development, and Hatching in the Crown-of-Thorns Seastar

et al. 2017

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Understanding the influence of environmental factors on the development and dispersal of crown-of-thorns seastars is critical to predicting when and where outbreaks of these coral-eating seastars will occur. Outbreaks of crown-of-thorns seastars are hypothesized to be driven by terrestrial runoff events that increase nutrients and the phytoplankton food for the larvae. In addition to increasing larval food supply, terrestrial runoff may also reduce salinity in the waters where seastars develop. We investigated the effects of reduced salinity on the fertilization and early development of seastars. We also tested the interactive effects of reduced salinity and reduced pH on the hatching of crown-of-thorns seastars. Overall, we found that reduced salinity has strong negative effects on fertilization and early development, as shown in other echinoderm species. We also found that reduced salinity delays hatching, but that reduced pH, in isolation or in combination with lower salinity, had no detectable effects on this developmental milestone. Models that assess the positive effects of terrestrial runoff on the development of crown-of-thorns seastars should also consider the strong negative effects of lower salinity on early development including lower levels of fertilization, increased frequency of abnormal development, and delayed time to hatching.

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Climate change as an unexpected co-factor promoting coral eating seastar (Acanthaster planci) outbreaks

Cited by 98 publications

References 56 publications

Visual orientation by the crown-of-thorns starfish (Acanthaster planci)

Visual orientation by the crown-of-thorns starfish (Acanthaster planci)

30 Years of Research on Crown-of-thorns Starfish (1986-2016): Scientific Advances and Emerging Opportunities

The Effects of Salinity and pH on Fertilization, Early Development, and Hatching in the Crown-of-Thorns Seastar

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