IPY: Shedding dynamic light on iron limitation: The interplay of iron limitation and dynamic irradiance in governing the phytoplankton distribution in the Ross Sea

0732535-凯文·阿里戈-斯坦福大学IPY：揭示铁限制的动态曙光：铁限制和动态光照在控制罗斯海浮游植物分布方面的相互作用南大洋在全球碳循环中发挥着重要作用，主要通过初级生产，约占海洋人为二氧化碳吸收总量的25%。在罗斯海，初级生产由两个在位置和时间上截然不同的分类群主导。硅藻在大陆架的浅混合层中占主导地位，而形成南极洲棕囊藻(Prymnesiophyceae)的菌落在混合程度较深的开阔区域占主导地位。值得注意的是，这两个群体具有非常不同的营养利用特征，并支持非常不同的海洋食物网。他们对气候变化的反应以及对碳出口的影响尚不清楚。以前的研究表明，光的可获得性和光气候的质量(静态和动态)在确定不同浮游植物类群何时何地开花方面发挥了重要作用。然而，亚北极和南大洋藻类群落的铁(Fe)限制现在已经有了很好的记录。此外，浮游植物对铁的需求随着光照的变化而变化。这项研究的主要假设是：铁限制和动态光照之间的相互作用控制着罗斯海浮游植物的分布。我们对这一假设的验证策略有三个方面：1)不同浮游植物类群在铁限制下对不同光条件的光适应将在实验室的受控铁条件下进行实验研究。2)在这些实验室实验中发现的光生理机制随后将在与国际国际年合作伙伴的两次巡航中进行实地测试。3)最后，在该项目的实验室和实地部分产生的数据将被用来对罗斯海的冰-大气-海洋耦合(CIAO)模式的动态光分量进行参数化。使用改进的模型，我们将运行未来的气候情景，以测试气候变化对南大洋浮游植物群落结构、分布、初级生产力和碳输出的影响。这项拟议的研究符合国际海洋年的主题“了解极地地区的环境变化”，并包括参加一次国际邮轮。详细的模型描述和这些研究产生的所有结果将通过DyaLiFe网站公开。改进CIAO模型将使我们和其他IPY合作伙伴有机会测试在当前和未来气候情景下观察到的南极浮游植物生理特征的生态后果。外展活动将包括参加斯坦福大学科学教师专业发展暑期计划、斯坦福大学地球科学学院高中实习计划，以及为当地科学培训中心(包括Chabot空间和科学中心)开发课程。

0732535 - Arrigo, Kevin - Stanford UniversityIPY: Shedding dynamic light on iron limitation: The interplay of ironlimitation and dynamic irradiance in governing the phytoplanktondistribution in the Ross SeaThe Southern Ocean plays an important role in the global carbon cycle, accounting for approximately 25% of total anthropogenic CO2 uptake by the oceans, mainly via primary production. In the Ross Sea, primary production is dominated by two taxa that are distinct in location and timing. Diatoms dominate in the shallow mixed layer of the continental shelf, whereas the colony forming Phaeocystis antarctica (Prymnesiophyceae) dominate in the more deeply mixed, open regions. Significantly, both groups have vastly different nutrient utilization characteristics, and support very different marine food webs. Their responses to climate change, and the implications for carbon export, are unclear. Previous studies show that light availability and the quality of the light climate (static versus dynamic) play a major role in defining where and when the different phytoplankton taxa bloom. However, iron (Fe) limitation of the algal communities in both the sub-Arctic and the Southern Ocean is now well documented. Moreover, phytoplankton Fe demand varies as a function of irradiance. The main hypothesis of the proposed research is: The interaction between Fe limitation and dynamic irradiance governs phytoplankton distributions in the Ross Sea. Our strategy to test this hypothesis is three-fold: 1) The photoacclimation of the different phytoplankton taxa to different light conditions under Fe limitation will be investigated in experiments in the laboratory under controlled Fe conditions. 2) The photophysiological mechanisms found in these laboratory experiments will then be tested in the field on two cruises with international IPY partners. 3) Finally, data generated during the lab and field parts of the project will be used to parameterize a dynamic light component of the Coupled Ice Atmosphere and Ocean (CIAO) model of the Ross Sea. Using the improved model, we will run future climate scenarios to test the impact of climate change on the phytoplankton community structure, distribution, primary production and carbon export in the Southern Ocean. The proposed research complies with IPY theme" Understanding Environmental change in Polar Regions" and includes participation in an international cruise. Detailed model descriptions and all of the results generated from these studies will be made public via a DynaLiFe website. Improving the CIAO model will give us and other IPY partners the opportunity to test the ecological consequences of physiological characteristics observed in Antarctic phytoplankton under current and future climate scenarios. Outreach will include participation in Stanford's Summer Program for Professional Development for Science Teachers, Stanford's School of Earth Sciences high school internship program, and development of curriculum for local science training centers, including the Chabot Space and Science Center.