Influence of different light on growth and calcification of Galaxea astreata

Nubbins from Galaxea astreata in March were dissected and cultured in unifactor and control experiment.By the survey of growth characteristics and metabolic level under a range of light wavelength and light intensities, The results suggested the four spectral quality (240 μmol photons/m²/s) produced significant impacts on the areal zooxanthellae density (Z) and chlorophyll-a content (A) and showed a significant differences between control and treatment (p < 0.05).Both parameters of peaked at 380~460 nm, except carbohydrate, lipid content to almost 10-fold higher values for the Protein(P) and Carbohydrate(C).The light-dependant calcification rates (G_L), net photosynthesis (P_N) and gross photosynthesis (P_G) showed significant difference among them under a range of light wavelength and light intensities (p < 0.05).The increases of light-dependant calcification rates(G_L), gross photosynthesis (P_G) and net photosynthesis (P_N) Along with the increase of light intensities, and begin to stop increase or decrease when the light intensities peaked at a threshold that was found between the light intensity and photosynthetic efficiency.Accordingly, The ratio of light-dependant calcification rates (G_L) to dark calcification rates (G_D) and light-dependant calcification rates (G_L) to gross photosynthesis (P_G)remains a similar variation curve and the ratio ranges from 3.06 to 9.89 and 0.21 to 0.60.However, The ratio gross photosynthesis (P_G) to net photosynthesis (P_N) begin to decrease Along with the increase of light intensities and the ratio ranges from 1.20 to 2.69.