Short Presentation Australian Marine Sciences Association 2026 Conference

Subtropical corals in the Solitary Islands Marine Park: multi-decadal resilience despite severe disturbances, with management adapting to an emerging threat (138897)

Hamish A Malcolm 1 , Nicole Strehling 2 , Matt Nimbs 1 , Marine Lechene 3 , Maria Byrne 3 , Curtis Champion 1 , Steve J Dalton 4 , Tom Davis 5 , Renata Ferrari 6 , David Harasti 5 , David Maguire 7 , Stephen DA Smith 8 , Will F Figueira 3 , Brigitte Sommer 3
  1. Fisheries Research, NSW Department of Primary Industries and Regional Development, Coffs Harbour, New South Wales, Australia
  2. Solitary Islands Marine Park, NSW Department of Primary Industries and Regional Development, Coffs Harbour, New South Wales, Australia
  3. School of Life and Evironmental Sciences, The University of Sydney, Sydney, NSW, Australia
  4. Fisheries Management, NSW Department of Primary Industries and Regional Development, Coffs Harbour, NSW, Australia
  5. Fisheries Research, NSW Department of Primary Industries and Regional Development, Port Stephens, NSW, Australia
  6. Australian Institute of Marine Science, Townsville, QLD, Australia
  7. Cape Byron Marine Park, NSW Department of Primary Industries and Regional Development, Byron Bay, NSW, Australia
  8. Aquamarine Australia, Mullaway, NSW, Australia

Subtropical coral assemblages of Solitary Islands Marine Park (SIMP) are unique and resilient, with multi-decadal monitoring (2002-2023) showing persistence in %cover and assemblage structure, even with cumulative severe disturbances in many years. Yet, disturbances can intensify and new threats emerge. In 2024, numerous Crown-of-Thorns-Starfish (COTS) were observed in sanctuary zone at North Solitary Island. Subsequent surveys/sampling confirmed and evaluated a mixed species outbreak (Acanthaster solaris, A. brevispinus). Though A. solaris has occurred in the SIMP for >40 years, this was the first recorded outbreak in NSW and represented a range expansion for A. brevispinus. Initial surveys found both species feeding extensively on a range of corals. Further surveys assessed densities, predation, and coral impacts. As reef extent at this island is small, a COTS outbreak has potential to devastate coral biodiversity and impact associated social and economic values. Biota are protected within sanctuary zone and any intervention response required careful consideration. A science-driven and collaborative approach enabled effective management action. Three control efforts have been undertaken, euthanising over 150 COTS. Warmer waters and stronger currents associated with climate change are likely to increase COTS outbreaks. The response to this outbreak will inform development of a long-term surveillance and management program.