RAPID response to an extreme low ice year on Lake Erie

智力优势：冬季是我们理解湖泊生态系统的后勤障碍。PIS最近与加拿大和美国海岸警卫队及其破冰项目的合作，促进了自2007年以来对伊利湖的年度冬季调查。这些调查是在冰盖扩大时期进行的，记录了浮游植物的高生物量，通常是在离散的地层中，由丝状硅藻Aulacoseira islandica主导。虽然伊利湖具有与其相对较浅的水深相一致的高年中位数冰盖[AMIC]的特点，但它也显示出最大冰面范围的极端，从低冰年的约10%到高冰年的99%。虽然从2007年到2010年，埃里斯湖每年冬天的最大冰盖都达到了95%左右，但2011-12年的冬天正在发生很大的变化，气候反常地温暖，几乎没有冰盖。PIS将使用快速反应研究(RAPID)赠款来调查这个温暖和几乎不结冰的冬季浮游植物群落结构和功能的变化。具体地说，他们将检验这样一种假设，即在没有膨胀的冰盖的情况下，温暖的单体混合制度会抑制伊利湖中央盆地的硅藻生长。对冬季大量硅藻生长的抑制可能对伊利湖夏季发生的事件有重要影响。冬季硅藻大量生长的记录，加上测量到的低细菌分解率，导致湖底藻类净积累。随着夏季的推移和次生离子变暖，出口的硅藻生物量的细菌再矿化加速，耗尽了次生氧气。这些观察结果与一个关于湖泊功能的新假说是一致的，即冬季浮游植物的产生导致了伊利湖夏季的缺氧。伊利湖中央盆地的氧气枯竭是有据可查的，其影响范围从内部营养物质负荷增加到大型动物栖息地的丧失。在其最大范围内，该区域的面积可超过10,000平方公里，在表面面积上可与墨西哥湾的低氧“死亡区”相媲美。因此，与“典型”冬季冰盖相关的高浮游植物生物量积累的偏离可能反映在夏季测量的较高的低磁化溶解氧上。这一研究机会可以帮助确定气候变暖可能带来的环境变化。广泛的影响：保龄格林州立大学(BGSU)与美国海岸警卫队(USCG)建立了持续的教育合作。这个独特的项目的目标是让海岸警卫队的船员参与湖泊调查，旨在提高伊利湖冬季采样的时间和空间分辨率，因为在这段时期，极端天气条件挑战了我们的采样能力。北卡罗来纳州立大学的科学家将每两周访问一次这艘船，以领导课堂讨论并收集样本。船员有机会通过海军、海军陆战队和海岸警卫队学费援助计划支付的学费获得大学学分。

Intellectual Merit:Winter presents a logistical obstacle to our understanding of lake ecosystems. A recent collaboration of the PIs with the Canadian- and U.S. Coast Guards and their icebreaking programs has facilitated annual winter surveys of Lake Erie since 2007. Conducted during times of expansive ice cover, these surveys have documented high phytoplankton biomass, often in discrete formations and dominated by a filamentous diatom, Aulacoseira islandica. Whereas Lake Erie is characterized by a high annual median ice cover [AMIC] consistent with its relative shallow bathymetry, it also shows extremes in maximum ice extent ranging from ~10% in low ice years to 99% in high ice years. While maximum ice cover on Lake Eries has reached ~95% each winter from 2007-2010, the winter of 2011-12 is shaping up much differently, with unseasonably warm conditions and almost no ice cover. The PIs will use a Rapid Response Research (RAPID) grant to investigate the changes in phytoplankton community structure and function during this warm and practically ice-free winter. Specifically, they will test the hypothesis that the warm monomictic mixing regime that occurs in the absence of expansive ice cover suppresses diatom growth in Lake Erie's central basin. Suppression of abundant winter diatom growth may have important implications for events occurring during summer in Lake Erie. The documentation of abundant winter diatom growth, combined with low measured rates of bacterial decomposition results in net accumulation of algae on the lake bottom. As summer progresses and the hypolimnion warms, bacterial remineralization of the exported diatom biomass accelerates, depleting the hypolimnion of oxygen. These observations are consistent with a new hypothesis on lake function, namely that winter phytoplankton production drives Lake Erie summer hypoxia. Oxygen depletion in Lake Erie's central basin is well documented with effects ranging from enhanced internal nutrient loading to loss of habitat for macrofauna. At its full expanse, the area can exceed 10,000 km2, comparable in surface area to the low oxygen 'dead zone' in the Gulf of Mexico. Thus, deviation from the high phytoplankton biomass accumulation associated with 'typical' winter ice cover may be reflected in higher hypolimnetic dissolved oxygen measured during summer. This research opportunity can help define environmental changes that might be expected in a warming climate.Broader Impacts:Bowling Green State University (BGSU) has established an ongoing educational collaboration with the U.S. Coast Guard (USCG). The goal of this unique program is to engage Coast Guard crew members in limnological surveys intended to increase both temporal and spatial resolution of sampling during winter in Lake Erie, a period when extreme weather conditions challenge our ability to sample. BGSU scientists will visit the ship fortnightly to lead classroom discussions and pick up samples. Crew members have the opportunity to earn university credit with tuition costs covered by the Navy, Marine Corps, and Coast Guard Tuition Assistance Program.