Patterns of Ecosystem Function and Trophic Status in Well-mixed Subtropical Estuaries Undergoing Anthropogenic Modification

人为改变下混合良好的亚热带河口生态系统功能和营养状况的模式

• 批准号: 0545312
• 负责人: Marc Frischer
• 金额: --
• 依托单位: Skidaway Institute of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0545312&HistoricalAwards=false
• 关键词: Patterns; Ecosystem; Function; Trophic; Status

The long-term goal of this project is to understand how warm, well-mixed, subtropical estuaries vary their plankton community structure, function, and net ecosystem metabolism in response to increasing anthropogenic nutrient loading and natural environmental forcing. The approach is to continue a unique, long-term (19 years), temporally intensive (sampling twice per week) record in the Skidaway River estuary (Georgia, USA) of hydrography, nutrients, plankton and microbial communities, dissolved oxygen, and important living and non-living components of particulate matter. The record to date documents changes caused by cultural eutrophication throughout the food web from bacteria to copepods; independently collected evidence shows major declines in commercial catches of fin- and shellfish. Commonly accepted conceptual models and limited local evidence support the notion that gelatinous predators may benefit from the enhanced microbial food web and from decreased competition from vertebrates and invertebrates. These data will be used to evaluate estuarine biological and chemical responses to, and potential recovery from, the by-products of increasing human occupation of the coast, as well as chronic (long-term warming, rising sea level, extended drought or wet periods) and stochastic (tropical storms) patterns in natural phenomena. Questions to be addressed fall into two basic categories: (a) how do plankton communities (individual taxa and bulk properties) respond in structure and function to early stages of eutrophication that include changes in concentrations and ratios of all major inorganic and organic nutrients, and (b) are such changes consonant with accepted ecological theory for estuarine ecosystems?The working hypothesis is that changes in nutrient loading have altered the competitive balance among phytoplankton, bacteria, and associated microbial communities, thus impacting higher trophic levels. A major corollary is that changes in food web structure at the lower levels are driving a long-term shift from oxic towards hypoxic conditions, i.e. from autotrophy to net heterotrophy. These lower oxygen concentrations may facilitate the development of gelatinous predators communities to fill the void caused by declines in fin- and shellfish. This study aims to provide sound scientific data on historic and contemporary patterns in plankton community structure, ecosystem function, and relationships to environmental variables, including trends in dissolved oxygen, as well as the quantitative basis to evaluate basic ecological hypotheses regarding estuarine ecosystems. Broader impacts include an active outreach program, which will use the scientific results to improve science teacher and classroom education, as well as to increase the representation of African Americans and other minorities in aquatic sciences. These project components, fully integrated into the proposed research activities, will facilitate community awareness of linkages between population development, environmental quality, ecosystem operation, and resource conservation.

该项目的长期目标是了解温暖，混合良好，亚热带的河口如何改变其浮游生物群落的结构，功能和净生态系统代谢，以响应增加人为的养分载荷和自然环境强迫。这种方法是在Skidaway River河口（美国乔治亚州）（美国乔治亚州）的水文，营养素，浮游生物和微生物群落，溶解的氧气以及重要的生活和非生命的颗粒物重要的成分。迄今为止的记录记录了整个食物网络从细菌到copepods的文化富营养化引起的变化；独立收集的证据表明，鳍和贝类的商业捕获量大幅下降。普遍接受的概念模型和有限的本地证据支持这样的观念：凝胶状捕食者可能会受益于增强的微生物食品网，以及脊椎动物和无脊椎动物的竞争减少。这些数据将用于评估河口生物学和化学反应，并从天然现象中的慢性（长期变暖，海平面上升，延长的干旱或潮湿时期）以及自然现象中的随机（热带风暴）模式。要解决的问题分为两个基本类别：（a）浮游生物（个体分类和批量特性）在结构和功能方面如何对富营养化的早期阶段做出反应，包括所有主要的无机和有机营养素的浓度和比率的变化，以及（b）的变化与可接受的生态学竞争竞争性的变化有关，这是eStuarine road的变化？在浮游植物，细菌和相关的微生物群落中，从而影响了更高的营养水平。一个主要的推论是，较低水平的食物网络结构的变化正在推动从疾病到低氧条件的长期转变，即从自身萎缩到净杂交。这些较低的氧气浓度可能促进凝胶状捕食者群落的发展，以填补鳍和贝类下降引起的空隙。这项研究旨在提供有关浮游生物社区结构，生态系统功能以及与环境变量关系的历史和当代模式的合理科学数据，包括溶解氧的趋势，以及评估河口生态系统基本生态假设的定量基础。更广泛的影响包括一项积极的外展计划，该计划将利用科学成果来改善科学老师和课堂教育，并增加非裔美国人和其他少数民族在水生科学方面的代表性。这些项目组件完全集成到拟议的研究活动中，将促进社区对人口发展，环境质量，生态系统运营和资源保护之间联系的认识。