Crown-of-thorns starfish can help reefs thrive

Crown-of-thorns starfish (COTS), known for their toxin-laden thorns and destructive reputation, may actually play a positive role in coral reef ecosystems, according to new research from the University of Sydney. Contrary to their destructive image, low-density populations of these coral-eating starfish can contribute to coral biodiversity by allowing slower-growing coral species to thrive.

This finding challenges the long-held perception of COTS as purely harmful creatures. The research, published in Ecology and Evolution, examined coral feeding scars and surviving coral tissue at One Tree Island Research Station on the Great Barrier Reef. Sites with healthy fish populations that control COTS populations showed that these starfish consume a consistent amount of coral during each meal, leaving behind living coral tissue more frequently than causing complete destruction.

This suggests that COTS feeding, at low densities, can create space for slower-growing coral species to persist, thus increasing overall coral diversity. While destructive outbreaks of COTS can severely harm coral reefs, the research highlights the importance of balancing COTS population control with marine management practices to ensure the health of coral ecosystems.