Temporal variability in gametogenesis and spawning patterns of crown-of-thorns starfish within the outbreak initiation zone in the northern Great Barrier Reef

Caballes, Ciemon Frank, Byrne, Maria, Messmer, Vanessa, and Pratchett, Morgan S. (2021) Temporal variability in gametogenesis and spawning patterns of crown-of-thorns starfish within the outbreak initiation zone in the northern Great Barrier Reef. Marine Biology, 168 (1). 13.

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Abstract

Population outbreaks of the coral-eating crown-of-thorns starfish (CoTS) have resulted in extensive coral mortality on reefs in the Indo-Pacific region and is considered one of the major contributors of significant declines in coral cover in Australia's Great Barrier Reef (GBR). Effective management of CoTS outbreaks rely on improved understanding of the drivers of individual and population-level differences in reproductive patterns, particularly those factors that may contribute to step-changes in reproductive success, such as the timing and synchronicity of spawning. This study investigated gametogenesis and spawning patterns in a persistent population of CoTS at one reef within the putative initiation zone where outbreaks appear to start in the GBR. We examined variation in the progression of gametogenesis and spawning patterns over two distinct spawning seasons (2013-2014, 2014-2015), using a variety of methods: macroscopic examination of gonads, assessment of monthly changes in the gonadosomatic index, analysis of histological sections of ovaries and testes, and comparison of the size-frequency distribution of oocytes. These methods yielded consistent results, which revealed striking variation in the timing of maturation and gamete release between two summer spawning seasons, possibly depending on local environmental conditions. The optimal temperature for gametogenesis and spawning occurred when seawater temperature exceeded 28 celcius. Gradual increases in temperature (to > 28 celcius) over spawning months in 2013-2014 caused 'batch/dribble' spawning, while abrupt increases in temperature in 2014-2015 caused synchronous 'all-at-once' spawning. During more rapid warming events in the typical summer spawning period, CoTS may exhibit greater synchronicity in their reproductive capacity, which may help seed outbreaks. This work advances our understanding of the mechanisms surrounding periodic fluctuations in CoTS densities and improves predictions on how this corallivorous predator will respond to environmental perturbations due to climate change.

Item ID: 66130
Item Type: Article (Research - C1)
ISSN: 1432-1793
Keywords: gametogenesis, Spawning patterns, coral, crown-of-thorns starfish, CoTS
Copyright Information: © The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature 2021.
Funders: Ian Potter Foundation (IPF), ARC Centre of Excellence for Coral Reef Studies, James Cook University (JCU), Australian Government’s National Environmental Science Program (NESP)
Date Deposited: 17 Feb 2021 18:26
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 20%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310903 Animal developmental and reproductive biology @ 50%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310913 Invertebrate biology @ 30%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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