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Understanding of the links between coral reef ecosystems, the goods and services they provide to people, and the wellbeing of human societies.


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Examining the multi-scale dynamics of reefs, from population dynamics to macroevolution


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Coral Reef Studies

From 2005 to 2022, the main node of the ARC Centre of Excellence for Coral Reef Studies was headquartered at James Cook University in Townsville, Queensland (Australia)

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Environmental influences on the reproductive biology and early life history of the crown-of-thorns starfish


Wednesday, December 7th, 2016 - 10:00 to 11:00 hrs.

Building 19, Room 106, JCU Townsville Campus
Ciemon Caballes
Ciemon Caballes

Abstract: Population outbreaks of the coral-eating crown-of-thorns starfish (CoTS), Acanthaster spp., often result in extensive coral mortality with highly extended recovery times, thereby contributing significantly to sustained and ongoing declines in coral cover across the Indo-Pacific.  Longterm or permanent solutions depend on filling crucial gaps in our knowledge of the biology of CoTS, particularly its reproductive biology and early life history, to understand the initiation and spread of outbreaks. Populations of CoTS are typically predisposed to major fluctuations due to inherent properties of their life history such as high fecundity, high fertilization rates, and short generation times. However, densities of Acanthaster spp. vary enormously in space and time, pointing to major fluctuations in reproductive success. The overarching question therefore is: what limits recruitment success in CoTS? Small environmental perturbations that trigger life-stage-specific responses can have pronounced effects on recruitment success and hence, on the dynamics of adult populations of CoTS. My research explored the role of environmental factors on (1) gametogenesis and reproductive timing; (2) spawning induction and synchronicity; (3) fertilization and embryonic development; and on (4) larval vitality, in relation to maternal provisioning and larval nutrition.  Environmental factors influenced variability in reproductive behaviour and output, life-stage-specific responses, and larval survival, growth, and development.  Taken together, these results demonstrate that variable sensitivity of early life history stages and processes to environmental factors can have flow-on effects that disproportionately impact recruitment success and population replenishment in CoTS.

Biography: Ciemon completed his BSc in Biology at Silliman University in the Philippines.  He proceeded to work with the Coastal Conservation and Education Foundation after his undergraduate studies and was involved in several coral reef management projects throughout the Philippines.  He decided to pursue his MSc in Biology degree at the University of Guam, USA in 2006, where he studied the role of chemical cues on the feeding ecology and distribution of crown-of-thorns starfish (CoTS) populations around Guam.  After finishing his MSc, he continued to study and monitor chronic CoTS outbreaks on Guam’s reefs and collaborated with JCU on developing novel techniques to control CoTS populations. He is currently pursuing his PhD under the supervision of Prof. Morgan Pratchett, Dr. Andrew Hoey, Dr. Jairo Rivera-Posada, and Dr. Alexander Kerr. His PhD research explores the influence of environmental factors on the reproductive biology and early life history of CoTS.


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