Low-density crown-of-thorns feeding leaves coral remnants, study finds

What you need to know

• Living coral remained after most of the 260 observed feeding events: researchers recorded remnants in 72% of scars. The result challenges the assumption that every feeding event completely removes the coral at the scar site. 12
• Among 46 tracked scars with living tissue, 26% showed some regenerated coral tissue by week 22. Regeneration was observed in Montipora, Porites and Isopora, but not in the branching genera included in the observations. 1
• The authors propose that low-density feeding may limit fast-growing coral taxa while remaining compatible with recovery. The suggestion that this could maintain or increase coral diversity is a hypothesis, rather than a diversity outcome demonstrated by the study. 12
• The observations were made at two sites on one reef under low-density conditions. The study therefore does not show that the same pattern applies across reefs, coral communities or starfish densities. 1
• Low-density feeding should be distinguished from outbreaks. AIMS reported established outbreaks on five surveyed Great Barrier Reef reefs in 2026, with no severe outbreaks recorded, and identified climate-driven disturbance as an ongoing pressure. 3

Why this matters

The findings add detail to how coral responds after crown-of-thorns feeding, but they do not settle what role low-density starfish play in reef condition. For practitioners, the distinction between observed scar recovery and an unmeasured diversity benefit is important when interpreting the results or considering their relevance to management. 13

What happens next

The reporting leaves several questions open: whether remnants and regeneration lead to measurable changes in coral diversity or reef condition over longer periods, and how widely results from two low-density sites can be applied. The evidence supplied does not establish a management balance between retaining low-density populations and controlling outbreaks. 13

What we know

• Researchers followed scars made by individual crown-of-thorns seastars at two One Tree Reef sites between 2022 and 2024. 1
• The study dataset contained 260 scars; living coral remnants were recorded after 72% of feeding events. 1
• Of 46 scars with living remnants that were tracked, 26% showed some regenerated tissue by week 22. 1

What we don't know

• Whether the observed remnants and regeneration result in measurable changes to coral diversity or reef condition over longer periods. 1
• How well findings from two low-density sites on One Tree Reef apply to other reefs, coral communities and starfish densities. 1
• What management balance between controlling outbreaks and retaining low-density populations is supported by evidence beyond this study. 13

Read the reporting

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