Effects of various environmental factors on growth and biochemical components of Gracilaria bailinae

Abstract:

Gracilaria bailinae, the genus Gracilaria, is a commercially important species of red seaweeds, and is currently farmed in the ponds along the coast of south China. It is commonly used as the food source in abalone aquaculture and employed for the extraction of agar as a raw material. However, the optimum growth conditions of G. bailinae are unclear. This study examined the physiochemical responses of G. bailinae to different levels of temperature, light and salinity to determine the suitable environmental conditions for the growth of G. bailinae. Thalli of G. bailinae were cultured under different conditions of temperatures (18℃, 23℃, 28℃, 33℃, and 38℃), salinities (13, 18, 23，28, 33, and 38), and light intensities (3000 lx, 6000 lx, 9000 lx, and 12000 lx), and then the growth and biochemical components of the algal thalli were measured. The results showed that the optimum temperature for the growth of G. bailinae is in the range of 23-33℃. Under this temperature range, G. bailinae exhibited higher relative growth rate, higher contents of soluble protein and phycobiliprotein, and lower activity of peroxidase compared with other temperatures. The optimum salinity for the growth of G. bailinae is between 18-28, and G. bailinae displayed a higher tolerance to low salinity than to high salinity. The optimum light intensity for the growth of G. bailinae is 6000 lx. These results suggest that it is essential to choose suitable sea area or pond and season for successful mariculture.