Babcock Russell C, Dambacher Jeffrey M, Morello Elisabetta B, Plagányi Éva E, Hayes Keith R, Sweatman Hugh P A, Pratchett Morgan S
CSIRO Oceans and Atmosphere, Brisbane, Qld, Australia.
School of Plant Biology, University of Western Australia, Crawley, WA, Australia.
PLoS One. 2016 Dec 30;11(12):e0169048. doi: 10.1371/journal.pone.0169048. eCollection 2016.
The crown-of-thorns starfish Acanthaster planci (COTS) has contributed greatly to declines in coral cover on Australia's Great Barrier Reef, and remains one of the major acute disturbances on Indo-Pacific coral reefs. Despite uncertainty about the underlying causes of outbreaks and the management responses that might address them, few studies have critically and directly compared competing hypotheses. This study uses qualitative modelling to compare hypotheses relating to outbreak initiation, explicitly considering the potential role of positive feedbacks, elevated nutrients, and removal of starfish predators by fishing. When nutrients and fishing are considered in isolation, the models indicate that a range of alternative hypotheses are capable of explaining outbreak initiation with similar levels of certainty. The models also suggest that outbreaks may be caused by multiple factors operating simultaneously, rather than by single proximal causes. As the complexity and realism of the models increased, the certainty of outcomes decreased, but key areas that require further research to improve the structure of the models were identified. Nutrient additions were likely to result in outbreaks only when COTS larvae alone benefitted from nutrients. Similarly, the effects of fishing on the decline of corals depended on the complexity of interactions among several categories of fishes. Our work suggests that management approaches which seek to be robust to model structure uncertainty should allow for multiple potential causes of outbreaks. Monitoring programs can provide tests of alternative potential causes of outbreaks if they specifically monitor all key taxa at reefs that are exposed to appropriate combinations of potential causal factors.
刺冠海星（Acanthaster planci，COTS）对澳大利亚大堡礁珊瑚覆盖率的下降造成了巨大影响，并且仍然是印度 - 太平洋珊瑚礁面临的主要急性干扰之一。尽管爆发的根本原因以及可能应对这些原因的管理措施存在不确定性，但很少有研究对相互竞争的假说进行批判性和直接的比较。本研究使用定性模型来比较与爆发起始相关的假说，明确考虑正反馈、营养物质增加以及捕鱼导致海星捕食者减少的潜在作用。当单独考虑营养物质和捕鱼时，模型表明一系列替代假说能够以相似的确定性水平解释爆发的起始。模型还表明，爆发可能是由多种因素同时作用引起的，而不是由单一的近端原因导致。随着模型的复杂性和现实性增加，结果的确定性降低，但确定了需要进一步研究以改进模型结构的关键领域。只有当刺冠海星幼虫单独从营养物质中受益时，添加营养物质才可能导致爆发。同样，捕鱼对珊瑚减少的影响取决于几类鱼类之间相互作用的复杂性。我们的工作表明，旨在对模型结构不确定性具有稳健性的管理方法应考虑爆发的多种潜在原因。如果监测计划专门监测暴露于潜在因果因素适当组合的珊瑚礁上的所有关键分类群，那么这些计划可以对爆发的替代潜在原因进行检验。
