An adult crown-of-thorns starfish. Photo: David Clode // Unsplash
The crown-of-thorns starfish is a coral-eating predator that new research shows is uniquely adapted to not only survive, but benefit from coral bleaching events. The critter is a native to the Great Barrier Reef in the Indo-Pacific region, and has been deemed a species of concern, due to the significant damage it can do to coral, as Phys.org reports.
New information about the crown-of-thorns starfish has come from research led by Professor Maria Byrne from the School of Life and Environmental Sciences at the University of Sydney and published in the journal Global Change Biology. Byrne and colleagues found that juvenile crown-of-thorns starfish had a higher heat tolerance than not only coral, but also adults of the same species.
“We found juvenile crown-of-thorns starfish can tolerate almost three times the heat intensity that causes coral bleaching, using a model that measures temperature over time,” Professor Byrne told Phys.org. “This is an important finding that has implications for understanding the impacts of climate change on marine ecosystems, especially the influence of understudied small cryptic species. Juveniles might well benefit from warming waters.”
This heat tolerance, combined with the life cycle of the crown-of-thorns starfish makes it uniquely able to prey on vulnerable coral. The juvenile starfish are herbivorous and can therefore survive not only the temperatures that cause a bleaching event, but also the resulting lack in coral to feed on. In fact, the deteriorating coral gives the juvenile starfish a “rubble habitat,” that allows their numbers to build over time, according to Byrne. When the reef finally begins to regrow, the juveniles emerge fully grown and eat the new coral.
Previous research from Byrne suggests that the juveniles can wait for up to six years to grow into coral-eating adults. The resiliency, life cycle, and adaptability of the crown-of-thorns starfish add up to an organism that is uniquely suited to destroying coral reefs.
True to form, humans are also doing their part to exacerbate the problem. “Loss of natural predators due to overfishing and the buildup of nutrients in the water have been suspected to contribute to outbreaks of crown-of-thorns starfish. Now we have evidence that bleaching induced coral mortality could aid the sea floor-dwelling juveniles, leading to subsequent large waves of adults in reefs which exacerbate the ravages of climate change,” said Matt Clements, Ph.D. student and co-author of the study.
