Framed reef modules: a new and cost-effective tool for coral restoration

Coral reef ecosystems worldwide are facing significant damage due to climate change and human disturbances. Consequently, restoration actions have been implemented to repair degraded reef areas. However, many restoration efforts have been hindered by severe environmental conditions, which can hamper restoration success and create challenges in developing cost-effective coral reef restoration methods. To address this, we conducted a study to test a low-cost reef restoration tool known as "framed reef modules" (FRMs), specifically aiming to mitigate the impacts of typhoons. We measured the growth rates (after 300 days) and survivorship (after 400 days) of Acropora hyacinthus and A. microphthalma fragments located at different distances from substrates (H0, H10, H30, and H45). The FRMs were exposed to multiple typhoons, and despite the harsh conditions, they remained undamaged. For comparison, we also examined basalt grid plates buried in gravel. After 400 days, the H45 FRMs showed the highest survival rates (A. hyacinthus 86% and A. microphthalma 90%) compared to H30 FRMs (A. hyacinthus 80% and A. microphthalma 84%), H10 FRMs (A. hyacinthus 4% and A. microphthalma 24%), and H0 FRMs (A. hyacinthus 3% and A. microphthalma 22%). It was found that transplanted corals with a height of at least 30 cm from the substrate demonstrated resilience against impacts caused by macroalgae, turf algae, and sedimentation rates. This study showed the effectiveness of an ecological engineering approach using FRMs to enhance the three-dimensional complexity of restored reefs and rehabilitate coral reefs damaged by typhoons. Furthermore, this method offered reduced costs and improved reef resilience.