Review status: a revised version of this preprint was accepted for the journal BG and is expected to appear here in due course.
Modelling Silicate – Nitrate - Ammonium co-limitation of algal growth and the importance of bacterial remineralisation based on an experimental Arctic coastal spring bloom culture study
Tobias R. Vonnahme1,Martial Leroy2,Silke Thoms3,Dick van Oevelen4,H. Rodger Harvey5,Svein Kristiansen1,Rolf Gradinger1,Ulrike Dietrich1,and Christoph Voelker3Tobias R. Vonnahme et al.Tobias R. Vonnahme1,Martial Leroy2,Silke Thoms3,Dick van Oevelen4,H. Rodger Harvey5,Svein Kristiansen1,Rolf Gradinger1,Ulrike Dietrich1,and Christoph Voelker3
Received: 14 Aug 2020 – Accepted for review: 28 Aug 2020 – Discussion started: 04 Sep 2020
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.
Replication Data for: Modelling Silicate – Nitrate - Ammonium co-limitation of algal growth and the importance of bacterial remineralisation based on an experimental Arctic coastal spring bloom culture studyTobias R. Vonnahme https://doi.org/10.18710/VA4IU9
Tobias R. Vonnahme et al.
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Diatoms are crucial for Arctic coastal spring blooms and their growth iscontrolled by nutrients and light. At the end of the bloom inorganic nitrogen or silicon can limit be limiting, but nitrogen can be regenerated by bacteria, extending the growth phase. Modelling these multi-nutrient dynamics and the role of bacteria is challenging, yet crucial for accurate modelling. We recreated spring bloom dynamics in a cultivation experiment and developed a representative dynamic model.
Diatoms are crucial for Arctic coastal spring blooms and their growth iscontrolled by nutrients...