不同磷条件下塔玛亚历山大藻氮的生态幅

藻类氮的生态辐是指在一定氮浓度范围内藻类能生长和繁殖的浓度范围。它由藻类生长的最佳氮浓度、氮适宜生长范围和氮耐受限度构成。为了定量计算藻类的氮生态幅,在室内培养条件下,研究了低磷(0.48 μmol/L)、中磷(0.97 μmol/L)和高磷(1.45 μmol/L)3种不同磷起始浓度条件下不同氮对塔玛亚历山大藻细胞数和最大比生长率的影响,依据Shelford耐受性定律建立了塔玛亚历山大藻生长的氮耐受性模型,并得到了藻类生长的最佳氮浓度、氮适宜生长范围和氮耐受范围的定量表达。结果表明,在低磷、中磷和高磷条件下,当氮浓度小于适合藻类生长的最佳氮浓度时,藻类细胞数和最大比生长率均随着氮浓度的增大而增大;当氮浓度大于适合藻类生长的最佳氮浓度时,藻类细胞数和最大比生长率均随着氮浓度的增大而减小。藻类生长的氮耐受性模型与谢尔福德耐受定律较为吻合,定量得到在低磷、中磷和高磷培养条件下塔玛亚历山大藻的最佳氮浓度分别为30.36、62.07和77.85 μmol/L;氮适宜生长范围分别为18.30-42.42、37.71-86.43和41.52-114.18 μmol/L;氮耐受限度分别为6.24-54.48、13.35-110.79和5.19-150.51 μmol/L。研究显示不同磷起始浓度条件下,藻类的氮生态幅也不相同。

On the ecological amplitude of nitrate of Alexandrium tamarense at different initial phosphate concentrations in laboratory cultures

The ecological amplitude of nitrate of algae can be defined in terms of the range of nitrate conditions under which it is able to grow and reproduce.It usually consists of the optimum nitrate concentrations,the optimum growth range of nitrate concentrations and the tolerance range of nitrate concentrations.In order to calculate the ecological amplitude of nitrate during algal growth,the relationship between nitrate concentration and the cell density,and that between nitrate concentration and maximum specific growth rate of Alexandrium tamarense were analyzed at three different fixed initial phosphate concentrations 0.48 μmol/L(low-P),0.97 μmol/L(medium-P) and 1.45 μmol/L(high-P)] in laboratory cultures.The experiments were carried out in three independent batch cultures respectively.The cell density and the specific growth rate were assessed as the response parameters.A nitrate tolerance model of algal growth was established following Shelford′s law of tolerance and using the experimental data.The results show that:(1) in low-P,medium-P,and high-P-grown cultures,both the cell density and the specific growth rate of A.tamarense increased when CN ≤ CNopt and then decreased when CN ≥ CNopt;(2) the nitrate tolerance model was consistent with Shelford′s law of tolerance;(3) the optimum nitrate concentrations in low-P,medium-P,and high-P grown cultures were 30.36,62.07 and 77.85 μmol/L,respectively;the optimum growth ranges of nitrate concentrations were 18.30—42.42,37.71—86.43 and 41.52—114.18 μmol/L,respectively,and the tolerance ranges of nitrate concentrations were 6.24—54.48,13.35—110.79 and 5.19—150.51 μmol/L,respectively.The results suggest that the ecological amplitude of nitrate during algal growth depended on the initial phosphate concentrations.