OCE-RIG: Refining a Diatom-Based Sea Ice Proxy for the Bering Sea Using Water, Ice and Sediment Samples to Improve the Robustness of Sea Ice Reconstructions

随着夏季海冰从北极消失，我们努力了解这种情况过去是否发生过，如果发生过，频率是多少。不幸的是，卫星自1979年以来才开始跟踪海冰。为了确定海冰的自然波动，我们需要更长的记录。沉积在海冰下的沉积物可以将海冰的记录延长数千年到数十万年。这个项目的基础是通过研究海冰中的硅藻(藻类)与下面沉积物中的硅藻之间的关系来开发海冰的替代物。该项目还将尝试通过引入一群来自爱荷华州的成绩优异、代表性不足的学生来激发海冰研究的兴奋，从而增加和多样化对海洋科学的参与。研究人员和学生将花一周时间从结冰的湖中收集冰芯并进行分析。学生们将体验野外工作，并将在偏远、奇异的地点所做的研究与他们自己的后院联系起来。尽管调查者的长期目标是将白令海的现代变化放在地质记录的背景下，但这个项目的具体目标是：1.确定2007.2和2006年春季白令海陆架上海冰和海水中硅藻的空间格局。确定从2015年夏天到2016年夏天，生活在楚科奇海陆架上的海冰和开阔水域中的硅藻的季节演替。调查者将研究海水、海冰和沉积物陷阱样本中的硅藻组合，然后将这些组合与下面顶层1厘米沉积物中的硅藻组合进行比较。海水和海冰样本是在2006年和2007年收集的，而沉积物陷阱样本将来自楚科奇生态系统系泊系统，该系统将于今年夏天开始收集硅藻沉积的完整年度周期。调查员将使用标准的计数方法和分类学，以1000倍的放大倍数对清洗过的硅藻进行计数，尽可能地识别物种水平。这项研究的驱动假设是，可以预测的硅藻亚群存在于冰藻和春季水华中，也存在于其正下方的沉积物中。这位研究人员还旨在验证长期以来的假设，即海冰硅藻优先在海面溶解。一个强大的海冰代理对于现实地重建北冰洋过去的海冰范围和退缩是至关重要的。这项工作将为基于统计的海冰在生态现实中的应用提供参考。这项试验性研究授予了爱荷华州立大学的一名正在建立实验室的新研究人员，她将被用来启动一项更大规模的海基研究，其中将包括在白令海部署沉积物捕集器。研究结果将使气候建模人员能够使用之前变暖期间的海冰记录来预测初级生产力和海冰在未来几十年将如何变化，并预测这种变化可能带来的生态系统规模的影响。

As summer sea ice disappears from the Arctic, we strive to know if this has happened in the past and if so, how often. Unfortunately, satellites have only been tracking sea ice since 1979. In order to determine natural fluctuations in sea ice, we need a much longer record. Sediments deposited below sea ice can extend the record of sea ice by thousands to hundreds of thousands of years. This project builds on work to develop a proxy for sea ice by looking at the relationship between diatoms (algae) found in sea ice and in the sediments below. This project will additionally attempt to increase and diversify participation in the ocean sciences by introducing a group of high-achieving, under-represented students from Iowa to the excitement of sea-ice research. The investigator and students will spend a week collecting an ice core from a frozen lake and analyzing it. The students will get to experience fieldwork and will connect research done in remote, exotic locations to the their own backyards.Although long-term goals of the investigator are to put modern changes in the Bering Sea in the context of the geological record, the specific goals of this project are to:1. Determine the spatial patterns of diatoms living in sea ice and sea water across the Bering Sea Shelf in spring 2006 and 2007.2. Determine the seasonal succession of diatoms living in sea ice and open water over the Chukchi Sea Shelf from summer 2015 to summer 2016.The investigator will examine diatom assemblages in a collection of seawater, sea ice, and sediment trap samples and then compare these assemblages to those in the top 1 cm of sediments below. Seawater and sea ice samples were collected in 2006 and 2007, while the sediment trap samples will come from the Chukchi Ecosystem Mooring which will begin collecting a full annual cycle of diatom sedimentation this summer. The investigator will count cleaned diatoms at 1000x magnification using standard counting methods and taxonomy, identifying to the species level whenever possible. The driving hypothesis of the research is that a predictable subset of diatoms is in the ice algal and spring blooms and is also in the sediments directly below. The investigator also aims to test the long-held hypothesis that sea ice diatoms are preferentially dissolved at the sea surface. A robust sea ice proxy is essential for realistically reconstructing past sea ice extent and retreat in the Arctic Ocean. This work will serve to ground statistically based sea ice proxy in ecological reality. This pilot study, awarded to a new researcher at Iowa State who is in the process of establishing her lab, will be leveraged to launch a larger, sea-based study that will include deploying sediment traps in the Bering Sea. Research results will enable climate modelers to use records of sea ice during previous warmings to predict how primary productivity and sea ice will change in the coming decades and to anticipate the ecosystem-scale impacts such changes may precipitate.