Coral growth rate in branching and massive coral in Sangiang Nature Tourism Park, Indonesia

Indonesia's coral reefs are deteriorating because of human activities, making rehabilitation crucial. Sangiang Island, a designated conservation area, has experienced significant coral degradation, necessitating restoration efforts. This study aimed to analyze the growth and survival rates (SR) of transplanted corals and determined the optimal seedling size for transplantation to aid coral reef rehabilitation. The study was conducted over seven months, from August 2019 to February 2020, on Sangiang Island. The transplanted coral species included Acropora sp., Platygira sp., and Favites sp., which represent branching and massive coral forms. Coral growth was measured using underwater photography and analyzed using CPCe software. Acropora sp. showed the highest growth rate (2.47 cm/month), while Platygira sp. and Favites sp. had average growth rates of 0.36 cm/month and 0.44 cm/month, respectively. SR was 70.7% for Acropora sp., 59.1% for Platygira sp., and 88.2% for Favites sp. The optimal fragment size for Acropora sp. was 11–20 cm, whereas smaller fragments (<10 cm) showing higher mortality. Coral transplantation effectively supports reef rehabilitation with survival rates above 50%. However, environmental challenges, such as sedimentation, macroalgae competition, and predation, must be addressed to improve the success rates.