RUI: Ecophysiology of gelatinous zooplankton in hypoxic estuaries

RUI：缺氧河口胶状浮游动物的生态生理学

• 批准号: 9986680
• 负责人: Erik Thuesen
• 金额: $ 21.53万
• 依托单位: Evergreen State College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9986680&HistoricalAwards=false
• 关键词: RUI; Ecophysiology; gelatinous; zooplankton; hypoxic

Estuaries are typically sites of natural hypoxia in summer for several reasons: lower freshwater inflows decrease turnover times, stratification increases, and increased surface primary production sinks to the bottom where it is remineralized thereby using up oxygen. Increased human population growth around the Puget Sound has increased the degree of hypoxia in the near-bottom depths of the estuary through increased nutrient influx and resulting eutrophication. Researchers in Chesapeake Bay have found that gelatinous zooplankton are able to survive in hypoxic bottom waters while their zooplankton prey (copepods and fish larvae) cannot tolerate such low levels of oxygen. This means that prey are concentrated in shallower zones while gelatinous predators can take advantage of the benefits of vertical migration. Therefore, increased hypoxia in estuaries due to human disturbances appears to alter pelagic food web structure by increasing the importance of gelatinous predators.This project will investigate the mechanisms that allow gelatinous zooplankton to survive at low oxygen levels. Previous research on the metabolic physiology of medusae, ctenophores, chaetognaths and other pelagic worms in midwater oxygen minimum layers has led the Investigator to propose several mechanisms whereby simple animals that do not have oxygen binding proteins or well developed circulatory systems may survive in low oxygen environments. Gelatinous zooplankters transferred from high-oxygen water to water depleted in oxygen leak oxygen into a closed chamber (Thuesen & Childress, unpublished; Thuesen & Lee, unpublished), and this project will describe and quantify the oxygen storage capabilities of mesoglea in the context of providing oxygen to gelatinous zooplankters during forays into hypoxic estuarine waters. This project will also investigate potential glycolytic adaptations in estuarine gelatinous zooplankton, including ctenophores, hydromedusae and scyphomedusae. The goals of this research are to (1) determine the oxygen regulatory abilities of gelatinous zooplankton; (2) measure the rate of oxygen release from mesoglea as a function of oxygen concentration in the surrounding water and determine if oxygen release is regulated by the organism; (3) determine the ratios of "oxygen storage potential" to metabolically active tissue through biochemical measurements and develop indices of hypoxia tolerance in gelatinous zooplankton to predict the abilities that different species may have for hypoxia survival; and (4) determine the role that anaerobic metabolism may have in the hypoxia tolerance of gelatinous zooplankton.The studies proposed here will complement studies on gelatinous zooplankton in hypoxic regions of the Chesapeake Bay through collaborations with scientists at the University of Maryland and the Estuarine Research Center of the Academy of Natural Sciences that will allow studies with specimens collected from hypoxic zones of the Chesapeake Bay. The proposed research will further our knowledge on the impact of hypoxia on Puget Sound food webs through collaborations with the Washington State Department of Ecology Marine Water Quality Monitoring Team. Students at The Evergreen State College will benefit through participation in this research through proposed RUI activities.

河口通常是夏季自然缺氧的地点，原因有几个：较低的淡水流入量减少周转时间，分层增加，增加的表面初级生产下沉到底部，在那里被矿化，从而消耗氧气。普吉特湾周围人口增长的增加，通过增加营养物质流入和导致的富营养化，增加了河口近底深度的缺氧程度。切萨皮克湾的研究人员发现，凝胶状浮游动物能够在缺氧的底层沃茨中生存，而它们的浮游动物猎物（桡足类和鱼苗）无法忍受如此低的氧气水平。这意味着猎物集中在较浅的区域，而凝胶状捕食者可以利用垂直迁移的好处。因此，由于人类活动的干扰，河口缺氧的增加似乎改变了浮游食物网的结构，增加了胶质捕食者的重要性。本项目将研究胶质浮游动物在低氧水平下生存的机制。 先前关于水母、栉水母、毛颚类和其他中上层蠕虫在中层氧气最低层中的代谢生理学的研究已经使研究者提出了几种机制，即没有氧结合蛋白或发达的循环系统的简单动物可以在低氧环境中生存。从高氧水中转移到贫氧水中的胶质动物胶凝体将氧气泄漏到封闭室中（Thuesen奇尔德里斯，未发表; Thuesen Lee，未发表），该项目将描述和量化中胶凝体在向胶质动物胶凝体提供氧气的背景下进入缺氧河口沃茨的储氧能力。本项目还将调查河口凝胶状浮游动物，包括栉水母、水螅水母和钵水母的潜在糖酵解适应。本研究的目的是：（1）确定胶质浮游动物的氧调节能力：（2）测量中胶层的氧释放速率作为周围水体中氧浓度的函数，并确定氧释放是否受生物体的调节;（3）确定“储氧潜力”的比值通过生物化学测量代谢活性组织，并开发凝胶状浮游动物耐缺氧指数，以预测不同物种可能具有的缺氧生存能力;以及（4）通过与马里兰州大学和自然科学院河口研究中心的科学家合作，确定厌氧代谢可能在凝胶状浮游动物耐缺氧性中的作用。这里提出的研究将补充切萨皮克湾缺氧区域的凝胶状浮游动物研究，这些研究将允许使用标本进行研究是从切萨皮克湾的缺氧区采集的。拟议的研究将通过与华盛顿州生态部海洋水质监测小组的合作，进一步了解缺氧对普吉湾食物网的影响。在万年青州立学院的学生将受益于通过拟议的RUI活动参与这项研究。