Iron manganese co-limitation – a potential driver of Southern Ocean phytoplankton ecology

南大洋（SO）对全球碳循环有着不成比例的控制，从而影响着全球范围的气候。南大洋浮游植物是全球碳循环的主要驱动力，占全球年初级生产量的20%。在SO中，二氧化碳的生物吸收主要由微量金属铁（Fe）和光的可用性控制，这两者对于光合作用都是必不可少的。虽然到目前为止，大多数研究都集中在解开铁和光如何影响SO浮游植物的生长和生产力，但几乎不知道其他微量金属（如锰）是否也作为SO中的限制或共同限制营养素。锰是所需的各种细胞过程中的浮游植物细胞，并已建议（共）限制与铁在某些部分的SO，如德雷克海峡。目前，我们缺乏信息的生长，光合作用，氧化胁迫和锰和铁的限制下的SO浮游植物物种的需求。本研究旨在提高我们对铁锰共同限制对SO浮游植物生理的潜在影响及其对当前和未来SO生态学和地球化学的影响的认识。为此，SO浮游植物的响应将研究在不同的光照条件下，模拟不同的气候变化情景下，改变铁和锰的有效性。将采用多学科方法，将生物学和海洋化学结合起来，并将实验室工作和实地工作结合起来。实验室实验与生态和地球化学重要的浮游植物物种的SO将提供一个机械的生理过程，如光合作用和微量金属的要求的理解。船上操作实验与自然SO浮游植物组合的SO的不同区域将进一步揭示铁锰共同限制的发生，并将有助于确定浮游植物物种在该领域，这是特别敏感的，但也容忍改变微量金属和光的可用性。总之，这项研究项目将有助于评估的SO关键浮游植物物种的空间分布在现在和未来SO的生理生态学解释。提高对SO生态系统功能和敏感性的认识对于改进我们现有的预测工具（例如建模）和增加我们对SO影响全球气候过程的机制的理解至关重要。因此，本研究项目将对DFG Schwerpunktprogramm 1158 Antarktis-Forschung中的关键研究课题2.2.4环境变化响应做出重大贡献。

The Southern Ocean (SO) exerts a disproportional control on the global carbon cycle, thus affecting climate at a global scale. Southern Ocean phytoplankton are major drivers of global carbon cycling accounting for 20% of the global annual primary production. In the SO, the biological uptake of carbon dioxide is mainly controlled by the availability of the trace metal iron (Fe) and light, both being essential for photosynthesis. Whereas most studies so far focused on disentangling how Fe and light influence SO phytoplankton growth and productivity, almost nothing is known whether other trace metals such as manganese (Mn) also act as limiting or co-limiting nutrient in the SO. Mn is required for various cellular processes in phytoplankton cells and has been suggested to be (co-)limiting with Fe in some parts of the SO such as the Drake Passage. Currently, we lack information on growth, photosynthesis, oxidative stress and Mn and Fe requirements under Fe-Mn limitation for SO phytoplankton species. This research project aims to improve our understanding about the potential effects of Fe-Mn co-limitation on SO phytoplankton physiology and their implications for the ecology and biogeochemistry in the present and future SO. To this end, the responses of SO phytoplankton will be studied in response to altered Fe and Mn availabilities under different light conditions, simulating different climate change scenarios. A multidisciplinary approach will be followed that integrates biology and marine chemistry and combines laboratory and field work. Laboratory experiments with ecologically and biogeochemically important phytoplankton species of the SO will provide a mechanistic understanding on physiological processes such as photosynthesis and trace metal requirements. Shipboard manipulation experiments with natural SO phytoplankton assemblages of different regions of the SO will further reveal the occurrence of Fe-Mn co-limitation and will help to identify phytoplankton species in the field, which are particularly sensitive, but also tolerant towards altered trace metal and light availabilities. All together this research project will help to assess an ecophysiological explanation for the spatial distribution of SO key phytoplankton species in the present and the future SO. Improved knowledge on the functioning and the sensitivity of the SO ecosystem is pivotal to improve our existing predictive tools (e.g. modelling) and increase our understanding on the mechanisms, by which the SO affects climatic processes at global scale. Therefore, this research project will significantly contribute to the key research topic 2.2.4 Response to Environmental Change within the DFG Schwerpunktprogramm 1158 Antarktis-Forschung.