RAPID response to an extreme low ice year on Lake Erie

对伊利湖极低冰年的快速反应

• 批准号: 1230735
• 负责人: Robert McKay
• 金额: $ 1.53万
• 依托单位: Bowling Green State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-15 至 2014-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1230735&HistoricalAwards=false
• 关键词: RAPID; response; extreme; low; ice

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.

智力优势：冬季对我们理解湖泊生态系统构成了后勤障碍。 自2007年以来，PI与加拿大和美国海岸警卫队及其破冰计划的合作促进了伊利湖的年度冬季调查。这些调查是在冰盖扩张时期进行的，记录了高浮游植物生物量，通常是离散的地层，以丝状硅藻Aulacoseira islandica为主。 而伊利湖的特点是高的年平均冰盖[AMIC]与其相对较浅的水深测量一致，它也显示了极端的最大冰范围从低冰年的10%到高冰年的99%。虽然从2007年到2010年，每年冬天伊利湖的最大冰层覆盖率达到95%，但2011年到2012年的冬天却大不相同，气候异常温暖，几乎没有冰层覆盖。 PI将使用快速反应研究（RAPID）赠款来调查浮游植物群落结构和功能在这个温暖和几乎无冰的冬天的变化。 具体来说，他们将测试的假设，即温暖的单混合制度，发生在没有膨胀的冰盖抑制硅藻生长在伊利湖的中央盆地。抑制丰富的冬季硅藻的生长可能有重要的影响，在夏季发生的事件在伊利湖。丰富的冬季硅藻生长的文件，结合低测得的细菌分解率的结果在湖底的藻类净积累。随着夏季的进展和浅水层变暖，细菌矿化的输出硅藻生物质加速，耗尽浅水层的氧气。这些意见是一致的湖泊功能的一个新的假设，即冬季浮游植物生产驱动伊利湖夏季缺氧。伊利湖中央盆地的氧气消耗有据可查，其影响范围从内部营养负荷增加到大型动物栖息地的丧失。在其最大面积，面积可超过10，000平方公里，表面积相当于墨西哥湾的低氧“死区”。因此，从高浮游植物生物量积累与“典型”的冬季冰盖的偏差可能会反映在较高的hypolimnetic溶解氧在夏季测量。 更广泛的影响：鲍林绿色州立大学（BGSU）与美国海岸警卫队（USCG）建立了持续的教育合作关系。这个独特的计划的目标是让海岸警卫队船员参与湖沼调查，旨在增加伊利湖冬季采样的时间和空间分辨率，这是极端天气条件挑战我们采样能力的时期。BGSU的科学家将每两周访问一次该船，领导课堂讨论并采集样本。船员有机会获得大学学分，学费由海军、海军陆战队和海岸警卫队学费援助计划支付。