米氏凯伦藻生长对磷的响应及其吸收动力学研究

Studies on growth and phosphorous uptake kinetics of Karenia mikimotoi at the different phosphorous levels

摘要:

研究了3种不同无机磷水平培养条件下对米氏凯伦藻（Karenia mikimotoi）细胞密度、体积的影响以及米氏凯伦藻的磷吸收动力学行为。结果表明：不同无机磷水平培养条件对米氏凯伦藻的生长有显著影响。在整个实验期间，磷浓度越高，米氏凯伦藻细胞密度越高，而且从第12天开始到实验结束，高磷组中米氏凯伦藻细胞密度均显著高于中磷组和低磷组（P<0.05）；与之相反，低磷组中米氏凯伦藻细胞体积从第6天开始显著大于中磷和高磷组（P<0.05），而中磷组中米氏凯伦藻体积与高磷组差异不显著（P>0.05）。利用米氏方程可较好地拟合米氏凯伦藻对无机磷的吸收速率和初始磷浓度之间关系，其中米氏凯伦藻对无机磷的最大吸收速率（ρ_max）为18.587 fmol/（cell·h），半饱和常数（K_s）为0.490 μmol/L。鉴于东海赤潮高发区的海水中无机磷含量偏低的事实（0.10 μmol/L左右），米氏凯伦藻对无机磷的较强亲和力以及低磷条件下的持续增长潜力表明在低磷条件下甲藻对营养盐的吸收比硅藻更具有竞争力，从而驱动东海区硅藻赤潮和甲藻赤潮演替。

Abstract:

We conducted a series of conditional experiments to explore the changes in cell densities, volume and phosphorous uptake kinetics of Karenia mikimotoi at three different inorganic phosphorus levels. The results showed that the growth of K. mikimotoi was significantly affected by inorganic phosphorus levels, the cell densities in high-phosphorous (HP) group were significantly (P<0.05) higher than those in medium-phosphorous (MP) and low- phosphorous (LP) groups starting from the 12th day until to the end of experiment. On the contrary, the cell volume of K. mikimotoi which grew in LP group was significantly (P<0.05) greater than those in MP and HP groups from the 6th day, however, it was non-significantly different between MP and HP group (P>0.05). The relationship between inorganic phosphorus absorption rate and initial phosphorus concentration was preferably fitted by the Michaelis-Menten equation. According the equation, the maximum inorganic phosphorus absorption rate of K. mikimotoi (ρ_max) was 18.587 fmol/(cell·h) and the half-saturation constant (K_s) was 0.490 μmol/L. Given the fact that inorganic phosphorus content was low (approximately 0.10 μmol/L) in the East China Sea when dinoflagellates red tides occurred, and K. mikimotoi have strong affinity for inorganic phosphorus and continuous growth potential in low phosphorus condition indicate that dinoflagellates have more competitive nutriment absorption ability than diatom, which may promote the succession of the diatom and dinoflagellates red tides in the East China Sea.