Starfish Help Reefs Thrive At Low Densities
Research from the University of Sydney reveals that controlled populations of crown-of-thorns starfish can boost coral diversity by preventing dominant species from taking over, with living coral tissue remaining after almost 75% of feeding events
Crown-of-thorns starfish, infamous for causing mass coral destruction on the Great Barrier Reef, can have a positive impact on coral prevalence and diversity when present in controlled populations. A study led by Dr. Shawna Foo, a University of Sydney Horizon Fellow, found that at low densities, these starfish support coral biodiversity by preventing dominant coral species from monopolizing reef space.
The Great Barrier Reef has recorded four major outbreaks of crown-of-thorns starfish since the 1960s, with outbreaks occurring approximately every 15 years. However, the research suggests that when these starfish are present in low numbers, they can actually help to increase coral diversity. The study found that remnants of fast-growing Acroporidae corals did not regenerate over crown-of-thorns starfish feeding scars, while regeneration occurred mostly among slower-growing Montipora and Porites corals.
A survey at the University of Sydney's One Tree Island Research Station found that living coral tissue remained after almost 75% of the crown-of-thorns starfish feeding events examined. This challenges the perception of crown-of-thorns starfish as purely destructive and suggests that they can play a role in maintaining healthy coral reefs.
## Why it matters The findings of this study are significant because they suggest that crown-of-thorns starfish can be a natural part of a healthy coral reef ecosystem. By preventing dominant coral species from taking over, these starfish can help to maintain biodiversity and promote the growth of slower-growing coral species. This is important for the long-term health of coral reefs, which are vulnerable to a range of threats including climate change and overfishing.
The research also highlights the importance of maintaining healthy populations of crown-of-thorns starfish predators, including tritons and multiple coral reef fishes. Diminishing populations of these predators can heighten the vulnerability of the reef and marine environments worldwide to crown-of-thorns starfish outbreaks.
## What happens next The study's findings have implications for the management of coral reefs and the control of crown-of-thorns starfish populations. By understanding the role that these starfish play in maintaining healthy coral reefs, conservation efforts can be targeted more effectively to promote biodiversity and prevent outbreaks.
The research was led by Dr. Shawna Foo, a University of Sydney Horizon Fellow from the School of Life and Environmental Sciences, and was published in Ecology and Evolution. The study provides new insights into the complex relationships between crown-of-thorns starfish and coral reefs, and highlights the need for a more nuanced approach to managing these ecosystems.
