The hidden army: corallivorous crown-of-thorns seastars can spend years as herbivorous juveniles

• Published in: Biology letters (2005) Vol. 16; no. 4; p. 20190849
• Main Authors: Deaker, Dione J, Agüera, Antonio, Lin, Huang-An, Lawson, Corinne, Budden, Claire, Dworjanyn, Symon A, Mos, Benjamin, Byrne, Maria
• Format: Journal Article
• Language: English
• Published: England The Royal Society 01.04.2020
• Subjects: Animals; Anthozoa; Conservation Biology; Coral Reefs; Diet; Herbivory; Starfish; crown-of-thorns starfish; Acanthaster sp; juvenile; herbivores
• ISSN: 1744-9561; 1744-957X
• DOI: 10.1098/rsbl.2019.0849

Crown-of-thorns seastar (COTS) outbreaks are a major threat to coral reefs. Although the herbivorous juveniles and their switch to corallivory are key to seeding outbreaks, they remain a black box in our understanding of COTS. We investigated the impact of a delay in diet transition due to coral scarcity in cohorts reared on crustose coralline algae for 10 months and 6.5 years before being offered coral. Both cohorts achieved an asymptotic size (16-18 mm diameter) on algae and had similar exponential growth on coral. After 6.5 years of herbivory, COTS were competent coral predators. This trophic and growth plasticity results in a marked age-size disconnect adding unappreciated complexity to COTS boom-bust dynamics. The potential that herbivorous juveniles accumulate in the reef infrastructure to seed outbreaks when favourable conditions arise has implications for management of COTS populations.