Abstract. Predatory release has long been considered a potential contributor to population outbreaks of crown-of-thorns starfish (CoTS; Acanthaster spp.), which has initiated extensive searches for potential predators that may consume large numbers of CoTS at high rates, but are also vulnerable to over-fishing. As such, most research into predation on crown-of-thorns starfish has focused on large reef fishes and invertebrates capable of capturing and consuming adult starfish. By contrast, consideration of smaller-bodied and potentially cryptic predators that could consume CoTS gametes, larvae or newly settled juveniles has received little attention. These smaller predators may be no less important in regulating the abundance of CoTS. Indeed, the collective consumption of CoTS, at different life-history stages, by a multitude of different organisms is likely to suppress the local abundance of CoTS, and thereby mediate the severity of outbreaks. My research, therefore, examines interspecific variation in the potential importance of planktivorous damselfishes as predators of CoTS eggs and larvae, as well as considering the influence of benthic predators on microhabitat preferences and settlement success of CoTS. Importantly, my research reveals that eggs and larvae of CoTS are consumed in considerable numbers by a broad range of planktivorous fishes and benthic invertebrates. Predatory species such as Amblyglyphidodon curacao and Dascyllus aruanus may be particularly important in consuming large numbers of eggs and/or larvae, whilst species such as Abudefduf sexfasciatus and Pomacentrus amboinensis that preferentially consume CoTS over alternative prey may also play a significant role in reducing larval densities. Furthermore, I reveal that CoTS are highly vulnerable to benthic predators during settlement, and variation in the abundance of benthic predators may exert a significant influence on patterns of settlement for this starfish. Unfortunately, many of the predators that consume CoTS gametes, larvae or newly settled juveniles are vulnerable to reef degradation and coral loss. It is, therefore, possible that anthropogenic degradation of reef ecosystems is contributing to the incidence and/or severity of CoTS outbreaks by mediating the abundance of these key predators.
Biography. Zara grew up in the UK and achieved her BSc (Hons) Biological Sciences at the University of Liverpool. She learnt to dive in Dahab, Egypt, returning a few years later to complete an internship with the Red Sea Environmental Centre, which confirmed her career path. Whilst diving in Thailand, Zara had her first encounter with a crown-of-thorns starfish (CoTS) outbreak and was immediately interested in the causes of these outbreaks and their effects on coral reef communities. Supervised by Prof. Morgan Pratchett and Dr. Vanessa Messmer within the ARC Centre of Excellence for Coral Reef Studies, Dr. Symon Dworjanyn at the National Marine Science Centre, and Dr. Scott Ling at the University of Tasmania, her PhD focuses on predation upon CoTS. Specifically, her research explores presumed anti-predator defences of the early life stages of this starfish, identifies new predators and determines patterns of predation upon larval starfish, and examines the influence of benthic predators on microhabitat preferences and settlement success of CoTS.