塔玛亚历山大藻对氮和磷的吸收及其生长特性

参照塔玛亚历山大藻(Alexandrium tamarense)赤潮爆发时的物理条件，以f／2加富的人工海水为培养基，设定了不同的氮、磷水平，研究了在室内批量培养条件下，塔玛亚历山大藻对无机氮、磷的吸收和无机氮、磷对塔玛亚历山大藻细胞生长的影响．结果表明，3种氮浓度条件下，塔玛亚历山大藻的比生长速率几乎没有差异，但低氮(0．0882mmol·L-1)条件下，藻细胞的生物量最低；中氮(0．882mmol·L-1)条件下，藻细胞具有最大的生物量，分别比高氮(2．646mmol·L-1)和低氮下增加44．7％和53．6％．随着培养基中磷浓度的升高，藻细胞生物量也升高，在高磷(0．108mmol·L-1)条件下达到最大值17200cell·ml-1，但在中磷(0．036mmol.L-1)条件下藻细胞具有最大的比生长速率．藻细胞对氮、磷的吸收速率与生长状态有密切关系，氮、磷限制条件下生长的藻细胞对氮、磷有快速的吸收．研究显示，低的N／P比有利于塔玛亚历山大藻的生长分裂，对数生长后期适当补氮则有利于其生物量的积累．

Nitrogen and phosphorus absorption and growth characteristics of Alexandrium tamarense

The uptake of nitrate and phosphate by Alexandrium tamarense and its growth characteristics were studied in laboratory cultures, which were conducted using environmentally realistic levels of physical factors during red tide occurrences. The results indicated that the specific growth rate had little difference under three nitrate levels (low-nitrate, 0.0882 mmol.L-1; middle-nitrate, 0.882 mmol.L-1; high-nitrate, 2.646 mmol.L-1). The cell yield was the lowest at low-nitrate, a maximum yield was achieved at the middle-nitrate, which increased by 44.7% and 53.6% respectively, compared with high-nitrate and low-nitrate. The cell yield increased with increasing phosphate concentrations in cultures (low-phosphate, 0.0036 mmol.L-1; middle-phosphate, 0.036 mmol.L-1; high-phosphate, 0.108 mmol.L-1), and the maximum yield (17200 cell.ml-1) was observed at high-phosphate concentration, while the maximum specific growth rate occurred at middle-phosphate. The growth conditions had a significant effect on the uptake rate of nitrate and phosphate by cells, and the cells grown in low-nitrate and low-phosphate cultures had a higher uptake rate. Further experiment suggested that lower ratio of N/P promoted the propagation of cells, and the supplementation of nitrate at later exponential growth phase had a positive effect to the accumulation of biomass.