SGER: Hurricane Isabel Impacts on Chesapeake Bay

SGER：飓风伊莎贝尔影响切萨皮克湾

• 批准号: 0405022
• 负责人: Michael Roman
• 金额: $ 10万
• 依托单位: University of Maryland Center for Environmental Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-12-15 至 2004-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0405022&HistoricalAwards=false
• 关键词: SGER; Hurricane; Isabel; Impacts; Chesapeake

Hurricanes are natural events that can impose a major perturbation to estuarineecosystems. Some effects of previous hurricanes on Chesapeake Bay (e.g., Agnes in1972) had lasting impacts on submerged aquatic vegetation (drastic decrease) and onfisheries (e.g. soft clam and oyster decline after Agnes). This SGER (Small Grant for Exploratory Reserch) project will examinethe effects of Hurricane Isabel on the hydrographic and food-web structure ofChesapeake Bay. Hurricane Isabel, which struck Chesapeake Bay on September 18,2003, provides a unique opportunity to document and evaluate effects of a significant.disturbance event.. Winds in excess of 70 mph vigorously mixed Bay waters. A stormsurge, 6.12 ft at the Bay mouth took 18 hours to move up the Bay to Baltimore wheremaximum water level was 7.36 ft above mean high water. This significant intrusion ofshelf water redistributed salt, plankton and fish within Chesapeake Bay. The 2003 WaterYear (WY), which includes rainfall associated with Isabel (Oct . Sept) represented thehighest WY freshwater input to Chesapeake Bay since 1937. The passage of Isabelduring the unusually wet 2003 provides a unique opportunity to evaluate effects of amajor perturbation on already enhanced freshwater input to the Bay ecosystem. The project will involved a 7-day cruise in early November, 2003 in which the samesampling procedures are followed that were designated during the six TIES years (1995-2000) and two BITMAX years (2001-2002) thus providing an essential contrast toconditions that observed in the wake of Hurricane Isabel. Investigators will intensively measure the hydrographic and ecosystem structure of the main stem ofChesapeake Bay. On leg 1 (3 days) they will conduct continuous mapping using a towedundulating recorder and surface mapping system which measures temperature, salt,oxygen, chlorophyll and zooplankton (Optical Plankton Counter) along a 350-km axialtransect down the main stem of Chesapeake Bay and with up to 24 cross-Bay transectsspaced 10 km apart. The vertical and horizontal resolution of these measurements will beapproximately 1 m and 200 m, respectively. Maps of physical and biological propertieswill provide an essential background for the hydrographic, plankton and fish surveys thatwill follow. On the second leg (4 days) they will conduct hydrographic stations (CTDs)and measurements of nutrients, phytoplankton biomass and production, zooplanktonpump and acoustic measurements, and fish abundance/distributions (Tucker trawl andmidwater trawl) on 26 Bay-transects. CBOS moorings, including the damaged stations,will be maintained through the interval.

飓风是可以对河口生态系统造成重大扰动的自然事件。以往飓风对切萨皮克湾的一些影响（如1972年的艾格尼丝飓风）对水下水生植被（急剧减少）和渔业（如艾格尼丝飓风后软蛤和牡蛎的减少）产生了持久的影响。这个SGER（探索性研究小额资助）项目将研究飓风伊莎贝尔对切萨皮克湾水文和食物网结构的影响。飓风伊莎贝尔于2003年9月18日袭击了切萨皮克湾，它提供了一个独特的机会来记录和评估一场重大飓风的影响。干扰事件. .风速超过每小时70英里，猛烈地搅动着海湾水域。在海湾入口处，6.12英尺的风暴潮花了18个小时向海湾移动到巴尔的摩，那里的最高水位比平均水位高7.36英尺。这一重大的陆架水入侵重新分配了切萨皮克湾内的盐、浮游生物和鱼类。2003年水年（WY），其中包括与伊莎贝尔（10月10日）有关的降雨量。自1937年以来，9月7日是切萨皮克湾的最高淡水输入量。在异常潮湿的2003年，伊莎贝尔的通过提供了一个独特的机会来评估重大扰动对海湾生态系统已经增加的淡水输入的影响。该项目将于2003年11月初进行为期7天的巡航，其中遵循了六个TIES年（1995-2000）和两个BITMAX年（2001-2002）指定的采样程序，从而提供了与飓风伊莎贝尔之后观察到的条件的基本对比。调查人员将集中测量切萨皮克湾主要干流的水文和生态系统结构。在第1阶段（3天），他们将使用拖波记录仪和地面测绘系统进行连续测绘，该系统沿着切萨皮克湾主干350公里的轴向样带和相隔10公里的24个跨湾样带测量温度、盐、氧、叶绿素和浮游动物（光学浮游生物计数器）。这些测量的垂直和水平分辨率分别约为1米和200米。物理和生物特性的地图将为接下来的水文、浮游生物和鱼类调查提供必要的背景资料。在第二站（四天），他们将在26个湾样带进行水文测量站（CTDs），测量营养物质、浮游植物生物量和产量、浮游动物泵和声学测量，以及鱼类丰度/分布（塔克拖网和中水拖网）。CBOS系泊，包括受损的站，将在间隔期间进行维护。