Abstract

Background

Clarifying the relationship between photosynthesis and irradiance and accurately quantifying photosynthetic performance are of importance to calculate the productivity of phytoplankton, whether in aquatic ecosystems modelling or obtaining more economical production.

Results

The photosynthetic performance of seven phytoplankton species was characterized by four typical photosynthesis–irradiance (P–I) response models. However, the differences were found between the returned values to photosynthetic characteristics by different P–I models. The saturation irradiance (I_sat) was distinctly underestimated by model 1, and the maximum net photosynthetic rate (P_nmax) was quite distinct from its measured values, due to the asymptotic function of the model. Models 2 and 3 lost some foundation to photosynthetic mechanisms, that the returned I_sat showed significant differences with the measured data. Model 4 for higher plants could reproduce the irradiance response trends of photosynthesis well for all phytoplankton species and obtained close values to the measured data, but the fitting curves exhibited some slight deviations under the low intensity of irradiance. Different phytoplankton species showed differences in photosynthetic productivity and characteristics. Platymonas subcordiformis showed larger intrinsic quantum yield (α) and lower I_sat and light compensation point (I_c) than Dunaliella salina or Isochrysis galbana. Microcystis sp., especially M. aeruginosa with the largest P_nmax and α among freshwater phytoplankton strains, exhibited more efficient light use efficiency than two species of green algae.

Conclusions

The present work will be useful both to describe the behavior of different phytoplankton in a quantitative way as well as to evaluate the flexibility and reusability of P–I models. Meanwhile we believe this research could provide important insight into the structure changes of phytoplankton communities in the aquatic ecosystems.

中文翻译：

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基于光合作用-辐照度响应模型的浮游植物光合性能定量分析

摘要

背景

澄清光合作用和辐照度之间的关系并准确定量光合作用的性能对于计算浮游植物的生产力至关重要，无论是在水生生态系统建模还是更经济的生产中。

结果

通过四种典型的光合作用-辐照度（P - I）响应模型来表征七个浮游植物的光合性能。但是，通过不同的P - I模型发现的光合特性返回值之间存在差异。模型1明显低估了饱和辐照度（I _sat），并且由于模型的渐近函数，最大净光合速率（P _nmax）与测量值有很大差异。模型2和模型3失去了光合作用的基础，因此我_坐回去与测量数据显示出显着差异。高等植物模型4可以很好地再现所有浮游植物物种的光合作用辐照度响应趋势，并获得与实测数据接近的值，但拟合曲线在低辐照度下显示出一些细微的偏差。不同的浮游植物种类在光合生产力和特征上存在差异。与盐生杜氏藻（Dunaliella salina）或等鞭金藻（Isochrysis galbana）相比，桔梗侧柏（Platymonas subcordiformis）表现出更大的内在量子产量（α）和较低的I _sat和光补偿点（I _c）。微囊藻特别是在淡水浮游植物菌株中，铜绿假单胞菌的P _nmax和α最大，与两种绿藻相比，其光利用效率更高。

结论

目前的工作将有助于定量描述不同浮游植物的行为，以及评估P – I模型的灵活性和可重复使用性。同时，我们认为这项研究可以为水生生态系统中浮游植物群落的结构变化提供重要的见识。