Effects of LED Light Illumination on the Growth, Digestive Enzymes, and Photoacclimation of Goniopora columna in Captivity

SIMPLE SUMMARY: Coral aquaculture is a new industry, which is of great importance to the sustainable development of coral reefs and meeting commercial needs. Light sources are crucial for the growth of corals because zooxanthellae provide them with essential nutrients through photosynthesis. Different corals and zooxanthellae have different photoacclimation characteristics; therefore, selecting a suitable light wavelength remains the critical inhibitor of coral maintenance in marine aquariums. Accordingly, this study investigated the effects of different light wavelengths and feeding of G. columna. The results showed that blue light (440–470 nm) and purple light (400–430 nm) increased the protease and body protein in corals, and the growth and survival rate also increased. In summary, G. columna’s efficient cultivation can use 400–470 nm wavelengths as the primary source of illumination. ABSTRACT: Goniopora columna is a stony coral valued for its reef-building potential and its unique appearance. Thus, identifying the optimal culture conditions for G. columna would enable efficient cultivation and prevent the illegal exploitation of marine resources. Light sources are crucial for the growth of corals because zooxanthellae provide them with basic nutrients through photosynthesis. Different corals and zooxanthellae have different photoacclimation characteristics; therefore, selecting a suitable light wavelength remains the key inhibitor of coral maintenance in marine aquariums. Accordingly, this study investigated the effects of different light wavelengths on G. columna. It was illuminated for 6 or 12 h a day under white light, yellow light, red light (LR), green light (LG), blue light (LB), or purple light (LP) for 8 weeks. During the experiment, R(R; i.e., a formula feed that combines sodium alginate, protein and probiotics) of 5% (w/v) of G. columna tissue and skeletal dry weight was fed every day. Coral polyps were counted, zooxanthellae density, chlorophyll a concentration, specific growth rates, and survival rates were calculated; polyp stretching and contractile behaviors were observed; and body composition and digestive enzyme activity were analyzed. LB or LP (but not LG or LR) illumination for at least 6 h per day significantly promoted the growth, survival, protein content, and protease activity of the G. columna specimens. Furthermore, coral polyp extension reached 100% after 30 min of LP and LB light irradiation. Although no significant differences in the zooxanthellae density or chlorophyll a concentration were noted under various light wavelengths, significant reductions were detected in the absence of light. To achieve energy-efficient coral aquaculture with regard to G. columna cultivation, 6 h of LB or LP illumination per day can improve the growth.