Preliminary Study Of Ecology Characteristics On Sargassum Fusiforme And Sargassum Hemiphyllum (Turn.) Ag

preliminary studies of nutrition ecology characteristics on Sargassum fusiforme and Sargassumhemiphyllum (Turn.)Ag were carried on, from which effect of nutrient, salinity, temperature and light on uptake of N and P by Sargassum fusiforme and Sargassumhemiphyllum(Turn.)Ag, ecological species relationships between Sargassum fusiforme, Sargassum hemiphyllum(Turn.)Ag and Alexandrium sp , the organic secretion capacity of Sargassum fusiforme and Sargassum hemiphyllum (Turn.)Ag were researched on the condition of the laboratory. The results are as follows.uptake rate of N and P by Sargassum fusiforme were great on condition of high N, P concentrations, when the N and P concentration reached to 50μmol / L and 5μmol / L, the uptake rate of N, P which were saturated by Sargassum fusiforme reached to 1.369μmoL / (gh) and 0.143μmoL / (gh) respectively; Sargassum fusiforme had effective uptake rates at different ratio of N to P, the maximum uptake rate of N occurred in 10:1 of N to P ,and the maximum uptake rate of P occurred at 5:1 of N to P. Effect of different combined state N on uptake rate of N by Sargassum fusiforme were significantly differet(P<0.05). Sargassum fusiforme had effective uptake rates of NO3--N and NH4+-N when they coexisted in the medium. The uptake rate of N and P by Sargassum hemiphyllum (Turn.)Ag increased with the increasing concentration of N and P, the maximum uptake rate of N and P which were 2.397 and 0.229μmoL / (gh) occurred at concentration of 200μmol / L- N and 20μmol / L- P respectively, Sargassum hemiphyllum (Turn.)Ag had effective uptake rates at different ratio of N to P, the maximum uptake rate of N and P occurred at 10:1 of N to P, In the value range from1 to30 of N toP, Effect of N to P on uptake rate of Nand P by Sargassum hemiphyllum (Turn.)Ag were significantly differet (P < 0.05). Effect of different combined state N on uptake rate of N and P by Sargassum hemiphyllum (Turn.)Ag were significantly differet (P<0.05). Sargassum hemiphyllum (Turn.)Ag had effective uptake rates of NO₃^--N and NH₄⁺-N when they coexisted in the medium, the maximum uptake rate of N and P occurred at 2:1 of NO3--N to NH4₊^-N. N and P were most suitable uptaken by Sargassum fusiforme.In the combination range of salinity from 30 to 40, temperature from 15 to 20℃, illumination from 3000 to 5000 lx . The most suitable environment condition for N and P uptaken by Sargassum hemiphyllum (Turn.)Ag were salinity from 10 to50, temperature10 to 20℃, illumination from 3000 to 7000 lx ,respectively.In experimental settings conditions, Alexandrium sp had no significant effect on the growth rate of Sargassum hemiphyllum (Turn.)Ag; effect of Alexandrium sp on the growth rate of Sargassum fusiforme only in the control group with cultural density of 4 g/L density and 8 g/L(P < 0.05). Inhibition effect of Sargassum fusiforme and Sargassum hemiphyllum (Turn.)Ag on group growth of Alexandrium sp were significantly (P < 0.05), completely death phenomenon of Alexandrium sp appeared while the cultural density of Sargassum fusiforme and Sargassum hemiphyllum (Turn.)Ag were more than 4 g/L, inhibition effect of water-soluble extraction from the 2 marine algae on group growth of Alexandrium sp were significantly (P < 0.05), and the completely death phenomenon of Alexandrium sp occurred. And inhibition effect of fosters filtrate from Sargassum fusiforme and Sargassum hemiphyllum (Turn.)Ag on group growth of Alexandrium sp only occurred prime and mid period of the experiment process.In experimental settings conditions, protein were largerly secreted by the 2 marine algae in the culture density from 2 to 4 g/L. Polysaccharide were largerly secreted by Sargassum fusiforme in the cultural density from 1 to 4 g/L ; but quantity of polysaccharide secreted by Sargassum hemiphyllum (Turn.)Ag increased with the increasing of cultural density, and the maximum appeared when the cultural density were 8 g/L, quantity of protein secreted by the 2 marine algae first increased and then decreased with extending cultivation time, secreted quantity of polysaccharide first increased and then decreased with extending cultivation time only when cultural density were more than 4 g/L. The secreted rate of polysaccharide by the 2 marine algae increased with the increasion of the cultural density, while the secreted rate of protein first increased and then decreased with the increasion of the cultural density, and the maximum occurred when the cultural density were 1 g/L and 2 g/L respectively.