磷限制条件下单胞藻胞内磷储量差异机理研究

不同微藻细胞内磷含量的差异，在有害藻华的形成及优势种演替过程中具有重要作用，但对于不同微藻细胞内磷含量的差异的原因仍缺乏了解. 本文采用磷限制培养试验考察了4株典型海洋藻华单胞藻〔三角褐指藻(Phaeodactylum tricornutum)、多列拟菱形藻(Pseudo-nitzschia multiseries)、球等鞭金藻(Isochrysis galbana)、海洋原甲藻(Prorocentrum micans)〕的细胞内磷含量随时间的变化，并利用Droop模型计算了微藻的最大比生长速率(μ_max)与细胞内磷的最小配额(Q_min)，分析了Q_min与藻类性状的响应关系. 结果表明:①4种海洋微藻的细胞内磷含量随时间呈先增后减的趋势，并且细胞内磷含量变化的响应时间和响应程度存在种间差异；②4种海洋微藻的Q_min存在差异，其范围为0.71～1.68 μg/g，4种海洋微藻的比生长速率(μ)与其细胞内磷含量(Q)呈正相关；③Q_min与细胞体积呈显著正相关，Q_min与μ_max可能存在一定的相关关系，即μ_max较大的微藻其Q_min较小. 研究显示，与藻体积、μ_max相比，门水平上的差异可能对Q_min影响较小，而Q_min的较大差异可能是藻类对磷具有不同竞争能力的表现，因而在有害藻华形成过程中出现不同微藻优势种演替的现象. 

Mechanism of Intracellular Phosphorus Storage Differences in Several Unicellular Algae under Phosphorus Limitation

The intracellular phosphorus storage of microalgae plays an important role in regulating the formation and succession of harmful algal blooms. However, we know little about the factors that influence the intracellular phosphorus storage. In order to explore the intracellular phosphorus storage changes of different types of marine microalgae and their responses to algae traits, the intracellular phosphorus storage changes of four typical species of marine phytoplankton (Phaeodactylum tricornutum, Pseudo-nitzschia multiseries, Isochrysis galbana, Prorocentrum micans) over time were analyzed using phosphorus-limited culture test. The Droop model was used to calculate the maximum specific growth rates (μ_max) and minimal cell quota for P (Q_min) of the four typical species of marine phytoplankton under phosphorus limitation, and the response relationship between Q_min and algae traits was analyzed. The results showed that: (1) The intracellular phosphorus content of the four marine microalgae increased first and then decreased with time, and the response time and degree of response to changes in intracellular phosphorus content were different among species. (2) The Q_min varied among species and ranged from 0.71 μg/g to 1.68 μg/g. The specific growth rate (μ) of microalgae was positively correlated with its intracellular phosphorus content (Q). (3) Q_min was significantly positively correlated with cell volume, and there may be a certain correlation between Q_min and μ_max, that is, the microalgae with a larger μ_max had a smaller Q_min. This study shows that differences in phylum may have less impact on microalgal Q_min compared to microalgal volume and μ_max. The differences in Q_min among microalgae could explain their different phosphorus competition ability and help to understand the succession of different dominant species during the formation of harmful algal blooms.