Originally reported: 23 September 2026
This is the source report date, not necessarily the date of the event.
A study published on 23 September 2026 tracked coral feeding scars caused by low‑density Crown‑of‑Thorns starfish at One Tree Reef, revealing that most scars retain tissue remnants while a minority begin to regenerate after 22 weeks.
The report released on 23 September 2026 by researchers from the University of Sydney and the Marine Invertebrate Futures Group examined the fate of discrete feeding scars left by Crown‑of‑Thorns seastars (COTS) on One Tree Reef, a southern segment of the Great Barrier Reef. The team monitored individual scars for a period of 22 weeks, documenting changes in scar morphology, algal colonisation and coral regeneration.
Initial observations noted that COTS feeding events produced consistent scar sizes, regardless of season, confirming earlier work that the starfish consumes a similar volume of coral tissue each time it feeds. Over the monitoring interval, 72% of the scars retained visible tissue remnants around their perimeters. These remnants were most commonly derived from Porites colonies, accounting for 44% of the observed remnants, a pattern that aligns with historical data on Porites resilience.
Early successional stages of the scars were dominated by turf algae, which rapidly colonised the exposed substrate. By the 10‑week mark, researchers documented the appearance of crustose coralline algae (CCA) on many scar surfaces, suggesting a shift towards more stable algal communities. The presence of CCA is often interpreted as a precursor to coral recruitment under the intermediate disturbance hypothesis, though in this study regeneration remained limited.
Montipora‑dominated scars displayed some tissue regrowth, with new coral tissue observed within the scar boundaries by week 22. In contrast, scars on Acropora colonies remained covered by turf algae throughout the study period, showing no signs of regeneration. Overall, only 26% of the tracked scars exhibited any measurable coral tissue recovery at the 22‑week checkpoint.
The researchers also evaluated the probability of remnant occurrence relative to colony size and the amount of tissue removed. Larger colonies and those from which a greater proportion of tissue was consumed were more likely to retain peripheral remnants. However, the low‑density COTS population present during the study meant that mortality of entire colonies was uncommon, underscoring that limited predation does not inevitably lead to colony loss.
Statistical analysis revealed no significant seasonal variation in average scar size, reinforcing the notion that COTS feeding intensity is relatively constant across the year. The study’s caveats include its confinement to a single reef location and a maximum observation window of 22 weeks, which may not capture longer‑term recovery dynamics.
Future research directions outlined by the authors include extending the monitoring period beyond 22 weeks to assess longer‑term regeneration potential and examining how these scar dynamics influence broader reef‑wide community diversity. Understanding the balance between algal colonisation and coral regrowth could inform management strategies aimed at mitigating COTS impacts while supporting reef resilience.
Overall, the findings contribute nuanced insight into the immediate aftermath of COTS feeding events on the Great Barrier Reef, highlighting that while many scars retain remnants and early algal settlers, true coral regeneration remains limited within the observed timeframe.
Why this matters
Feeding scars from Crown‑of‑Thorns starfish are a common disturbance on the Great Barrier Reef. Knowing how quickly and to what extent coral can recover from these scars helps managers gauge the reef’s capacity to withstand repeated predation and informs targeted interventions to promote coral regeneration.
What happens next
The research team plans to monitor the same scar sites beyond the 22‑week period and to expand the study to additional reef locations to better understand long‑term recovery trajectories and ecosystem‑level effects.
Marine science glossary
- Feeding scar
- The area of coral tissue removed by a Crown‑of‑Thorns starfish during a single feeding event.
- Turf algae
- A fast‑growing, filamentous algal community that often colonises newly exposed reef surfaces.
- Crustose coralline algae (CCA)
- Hard, calcareous algae that can stabilise reef substrate and facilitate coral larval settlement.
- Intermediate disturbance hypothesis
- A theory suggesting that moderate levels of disturbance can enhance biodiversity by preventing competitive exclusion.