Effects of nitrogen, phosphorus and carbon on growth of seven marine microalgae

In order to screen fine algae species (strains) for in situ treatment of aquaculture tail water, we investigated the effects of nitrogen (nitrate, ammonium and urea), phosphorus (phosphate) and carbon (carbonate) on the growth of seven marine microalgae (Cochlodinium geminatum, Karenia mikimotoi, Skeletonema costatum, Chaetoceros muelleri, Phaeocystis globosa, Platymonas subcordiformis, Nannochloropsis oculata) in batch cultures. The results reaveal that the growth rates of microalgae were positively correlated with nutrients concentration. Compared with the control, the enhancements on the specific growth rate were 35%, 19% and 19% in C. geminatum, S. costatum and N. oculata under carbonate treatments. The enchancements on the specific growth rate under phosphate, nitrate, ammonium and urea were 25.01%−446.60%, 16.54%−77.52%, 15.79%−88.82% and 25.16%−71.43%, respectively. In general, the maximal specific growth rates (highest in P. globosa) of seven marine algae under carbon, nitrogen and phosphorus were negatively correlated with cell size, while those of P. subcordiformis and N. oculata were not significantly different with red tide microalgae except P. globosa. The nitrate and phosphate uptake rates were positively correlated with cell size, but the utilization efficiency of nitrogen/phosphorus per cell was negatively correlated with cell size. The N/P ratios in all culture medium increased. The phosphorus uptake rates were higher than nitrogen uptake rates. P. subcordiformis and N. oculata can be used in algal absorption of nitrogen and phosphorus in aquaculture tail water.