Abstract. Arctic coastal ecosystems are rapidly changing due to climate warming, which makes modelling their productivity crucially important to better understand future changes. System primary production in these systems is highest during the pronounced spring bloom, typically dominated by diatoms. Eventually the spring blooms terminate due to silicon or nitrogen limitation. Bacteria can play an important role for extending bloom duration and total CO₂ fixation through ammonium regeneration. Current ecosystem models often simplify the effects of nutrient co-limitations on algal physiology and cellular ratios and neglect bacterial driven regeneration, leading to an underestimation of primary production. Detailed biochemistry- and cell-based models can represent these dynamics but are difficult to tune in the environment. We performed a cultivation experiment that showed typical spring bloom dynamics, such as extended algal growth via bacteria ammonium remineralisation, and reduced algal growth and inhibited chlorophyll synthesis under silicate limitation, and gradually reduced nitrogen assimilation and chlorophyll synthesis under nitrogen limitation. We developed a simplified dynamic model to represent these processes. The model also highlights the importance of organic matter excretion, and post bloom ammonium accumulation. Overall, model complexity is comparable to other ecosystem models used in the Arctic while improving the representation of nutrient co-limitation related processes. Such model enhancements that now incorporate increased nutrient inputs and higher mineralization rates in a warmer climate will improve future predictions in this vulnerable system.

中文翻译：

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基于北极沿海沿海春季开花试验研究，模拟硅酸盐-硝酸盐-铵盐对藻类生长的共限制以及细菌再矿化的重要性

摘要。由于气候变暖，北极沿海生态系统正在迅速变化，这使得对其生产力进行建模对于更好地了解未来变化至关重要。在这些系统中，系统的主要产量在明显的春季开花期间最高，通常以硅藻为主。最终，由于硅或氮的限制，春季水华终止。细菌可以在延长开花时间和总CO _2中发挥重要作用通过铵再生固定。当前的生态系统模型通常会简化养分共存限制对藻类生理和细胞比例的影响，而忽略细菌驱动的再生，从而导致对初级生产的低估。基于生物化学和细胞的详细模型可以代表这些动态，但是很难在环境中进行调整。我们进行了一项培养实验，该实验显示了典型的春季开花动态，例如通过细菌铵再矿化延长了藻类的生长，在硅酸盐限制下减少了藻类的生长并抑制了叶绿素的合成，并在氮限制下逐渐减少了氮的同化和叶绿素的合成。我们开发了一个简化的动态模型来表示这些过程。该模型还强调了有机物排泄的重要性，并在开花后积累铵。总体而言，模型的复杂性可与北极地区使用的其他生态系统模型相提并论，同时提高了营养素共存限制相关过程的代表性。现在，在气候变暖的情况下，这样的模型增强结合了更多的养分输入和更高的矿化率，将改善对该脆弱系统的未来预测。