The anticipated long‐term rise in temperature can have numerous effects on freshwater phytoplankton, however, there is a great deal of uncertainty about how biogeochemical processes modify community functioning under a warming climate. Previous works regarding a large shallow lake and a mesocosm study showed a positive relationship between the temporal variability of phytoplankton composition and mean temperature, which might be a sign of warming‐stimulated instability in ecosystem processes. To elucidate whether these observations are part of a more general phenomenon, we combined a numerical model describing the dependence of algal growth on temperature and nutrient concentration with a multispecies, multi‐nutrient model. We ran simulations representative of changes in phytoplankton communities with randomized initial species composition under different temperature scenarios (current annual temperature pattern increased with 1°C, 2°C, or 3°C), various levels of nitrogen and phosphorus supply and different degrees of temporal variability in those supplies. The model outputs showed that seasonal variability in composition can be enhanced by warming through the mechanistic links between nutrient availability, temperature, and species‐specific growth rates, but the rate of increase is also dependent on nutrient ratios and the size of the species pool. Moreover, temporal variability in nutrient loads also enhanced compositional variability, but the rate of increase also depended on the level of nutrient supply. The results of our study hint that the impact of climate change and eutrophication on phytoplankton dynamics can be more intricate than spatiotemporally limited field or experimental observations would suggest.

中文翻译：

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变暖、营养物质和物种库大小对浮游植物组成季节性变化的综合影响：建模视角

预期的长期气温上升可能会对淡水浮游植物产生许多影响，然而，生物地球化学过程如何改变气候变暖下的群落功能存在很大的不确定性。先前关于大型浅湖和中生态系统研究的工作表明，浮游植物组成的时间变化与平均温度之间存在正相关关系，这可能是生态系统过程中变暖引起的不稳定的标志。为了阐明这些观察结果是否是更普遍现象的一部分，我们将描述藻类生长对温度和营养物浓度依赖性的数值模型与多物种、多营养物模型结合起来。我们进行了代表浮游植物群落变化的模拟，其中随机初始物种组成在不同温度情景（当前年温度模式增加 1°C、2°C 或 3°C）、不同水平的氮和磷供应以及不同程度的这些供应的时间变化。模型输出表明，通过养分有效性、温度和物种特定生长率之间的机械联系，变暖可以增强成分的季节性变化，但增加的速度也取决于养分比例和物种库的大小。此外，养分负荷的时间变化也增强了成分的变化，但增加的速度也取决于养分供应的水平。我们的研究结果表明，气候变化和富营养化对浮游植物动态的影响可能比时空有限的现场或实验观察所表明的更为复杂。