Effects in CO2 and light on the carbon acquisition of key diatom species in the Southern Ocean

南大洋的生态和生物地球化学主要由关键硅藻和鞭毛状棕囊藻主导。对这些物种在南大洋生态系统中优势地位的调节机制知之甚少。根据气专委(情景IS92a)，预计2100年地表水二氧化碳浓度将比工业化前的数值增加近三倍，并使pH值(“海洋酸化”)降低0.4个单位。气温上升将影响表层海洋分层，进而影响光照气候和来自深层的营养物质输入。气候模型表明，特别是南大洋将受到这些环境变化的影响。这些变化将如何塑造浮游植物群落结构，并可能改变生产力？为了回答这个问题，光合作用碳获取的研究在浮游植物生态学中变得越来越重要。在细胞和生态系统水平上研究CO2、光和铁对碳获取的影响，将为当前海洋浮游植物物种的空间分布提供生态生理学解释，并将进一步有助于预测未来群落结构的变化。此外，从该项目获得的结果将被纳入细胞模型，并将对改进生态系统模型的参数化特别相关。

The ecology and biogeochemistry of the Southern Ocean is strongly dominated by key diatom species and the flagellate Phaeocystis. The mechanisms regulating the dominance of these species in the Southern Ocean ecosystem are poorly understood. According to the IPCC (scenario IS92a), surface water CO2 concentrations are expected to increase almost three-fold for the year 2100 relative to preindustrial values and to lower the pH (‘ocean acidification’) by 0.4 units. Rising temperatures will impact surface ocean stratification, which in turn will affect light climate and nutrient input from deeper layers. Climate models indicate that especially the Southern Ocean will be affected by these environmental changes. How will these changes shape phytoplankton community structure and possibly alter productivity? To answer this question the investigation of photosynthetic carbon acquisition has gained increasing importance in phytoplankton ecology. Studying the effects of CO2, light and iron on the carbon acquisition at the cellular and the ecosystem level will provide ecophysiological explanations for the spatial distribution of phytoplankton species in the present ocean and will further help predicting changes in future community structures. Moreover, the obtained results from this project will be incorporated in a cellular model and will be of particular relevance for improving parameterization of ecosystem models.