Analyzing Adaptation Mechanisms in Artificial Transplantation of Galaxea fascicularis

Abstract

Coral reefs are among Earth's most biologically diverse and ecologically crucial ecosystems but face severe threats from climate change and human activities. Coral transplantation has become a key strategy for reef restoration. This study focused on transplanting Galaxea fascicularis at northern Wuzhizhou Island, Hainan, assessing physiological characteristics and metabolomic differences between transplanted and parent corals at 1, 6, and 12 months post-transplantation. Findings revealed that transplanted coral survival rates declined rapidly during the first 6 months but then stabilized. An algal bloom in May 2023 increased turbidity, dissolved inorganic nitrogen (DIN), and partial pressure of pCO2, negatively impacting coral photosynthesis and calcification and increasing physiological stress. From months 6 to 12, environmental conditions improved, with temperature and salinity aligning closely with natural conditions, dissolved oxygen levels recovering, turbidity decreasing significantly, and Ωarag reaching moderate levels, facilitating stable coral growth and calcification. By 12 months, transplanted corals reached sexual maturity, with notable increases in protein and lipid content. Metabolomic analysis showed that during the short-term (1 month) and mid-term (6 months) post-transplantation periods, the arachidonic acid metabolic pathway was upregulated while the glycerophosphate metabolic pathway was downregulated, enabling corals to cope with environmental stress and resource redistribution. By 12 months, oxidative phosphorylation was upregulated to meet reproductive energy demands. Results demonstrate that G. fascicularis can adapt well to restoration environments and achieve sexual maturity quickly, making it a suitable candidate for reef restoration.