Growth rate and temperature of freshwater phytoplankton from Morphology-based differences in the thermal response of freshwater phytoplankton.

The thermal response of maximum growth rate in morphology-based functional groups (MBFG) of freshwater phytoplankton is analysed. Contrasting an exponential Boltzmann–Arrhenius with a unimodal model, three main features were evaluated: (i) the activation energy of the rise (Er), (ii) the presence of a break in the thermal response and (iii) the activation energy of the fall (Ef). The whole dataset (N = 563) showed an exponential increase (Er ∼ 0.5), a break around 24°C and no temperature dependence after the breakpoint (Ef = 0). Contrasting thermal responses among MBFG were found. All groups showed positive activation energy (Er > 0), four showed no evidence of decline in growth rate (temperature range = 0–35°C) and two presented a breakpoint followed by a sharp decrease in growth rate. Our results evidenced systematic differences between MBFG in the thermal response and a coherent response significantly related to morphological traits other than size (i.e. within MBFG). These results provide relevant information for water quality modelling and climate change predictions.

本研究分析了淡水浮游植物基于形态学的功能群（morphology-based functional groups, MBFG）的最大生长速率热响应特征。本研究将指数型玻尔兹曼-阿伦尼乌斯模型与单峰模型进行对比，评估了三项核心特征：（i）升温阶段的活化能（Er）、（ii）热响应曲线是否存在温度拐点、（iii）降温阶段的活化能（Ef）。整体数据集（N=563）呈现指数增长趋势（Er≈0.5），温度拐点约为24℃，且拐点后生长速率不受温度影响（Ef=0）。研究发现不同MBFG的热响应存在显著差异：所有类群均表现出正活化能（Er>0），其中4个类群未观测到生长速率随温度下降的现象（温度区间为0~35℃），另有2个类群出现温度拐点后生长速率急剧下降。本研究结果证实，MBFG间的热响应存在系统性差异，且该热响应特征与MBFG内部除细胞尺寸外的其他形态性状显著相关，二者关联具有一致性。上述研究结果可为水质建模与气候变化预测提供重要参考依据。