Green Island reef rehabilitation MARRS reef star installation

The Green Island reef rehabilitation project aims to restore healthy coral cover to an area of impacted reef using innovative tools and techniques.

Located 27 kilometres from Cairns in the Great Barrier Reef Marine Park, Green Island is the site of an innovative five-year reef regeneration trial which launched November 2020.

Like many coral reefs, Green Island’s reef is showing signs of impact from accumulating environmental stressors including crown-of-thorns starfish, cyclones and most recently coral bleaching.

The Green Island reef rehabilitation project used a total of 2675 coral fragments, comprised of 2450 live fragments and 225 dead fragments. Approximately 2250 loose, live coral fragments were attached by hand to 165 interlocked hexagonal, sand-coated metal frames called ‘MARRS reef stars’. The remaining 200 live coral fragments connected to hard substrate using Coralclips® developed through the Coral Nurture Program. The 225 dead coral fragments were collected and used alongside the live coral fragments on the MARRS reef stars, as part of a study trialling biodegradable cable ties.

The live coral fragments will grow over their new stable location to form a diverse and healthy area of live reef where previously there had been unstable dead coral rubble and bare limestone rock.

This direct rehabilitation project is a joint initiative between the Great Barrier Reef Marine Park Authority, Queensland Parks and Wildlife Service, Mars Incorporated, Quicksilver Cruises and Big Cat Green Island Cruises, the Coral Nurture Program and Gunggandji Traditional Owners.

This project will run over five years and involve ongoing and regular site management and detailed monitoring every six months.

Key points:

  • The project included the installation of a total of 165 reef stars and 200 Coralclip® devices with the key objective of improving coral cover through an area of approximately 200m² of unstable coral rubble and coral rock.
  • A total of approximately 2675 coral fragments were used. The fragments came from pieces of coral found lying loose on the seabed (likely broken off by rough weather, large fish or other physical impacts) where they were unlikely to survive.
  • A trial of fully biodegradable cable ties is also underway, using 225 dead coral fragments. These biodegradable cable ties are made of a potato starch and are being tested to see if they are suitable for use in future reef rehabilitation projects.
  • The project has allowed local operators, private companies, the Gunggandji Traditional Owners and marine park management agencies to work together in a way that is encouraged through the Authority’s Great Barrier Reef Blueprint for Resilience that encourages new ideas and partnerships to improve Reef health.
  • The site is in only 4-6m of water and available for both confident snorkelers and scuba divers to visit and see how these techniques can improve hard coral cover in ‘high-value’ sites.