Collaborative Research: Groundwater Discharge, Benthic Coupling and Microalgal Community Structure in as Shallow Coastal Lagoon

合作研究：浅滩泻湖地下水排放、底栖耦合和微藻群落结构

• 批准号: 0961970
• 负责人: William Burnett
• 金额: $ 22.96万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961970&HistoricalAwards=false
• 关键词: Collaborative; Research; Groundwater; Discharge; Benthic

Numerous studies over the past few decades have shown that submarine groundwater discharge (SGD) transports significant quantities of nutrients to estuaries and nearshore oceans worldwide. So far, none of the geochemical and hydrological studies of SGD have demonstrated a clear ecological role. At the same time, studies of microalgal community dynamics have suggested, but not verified, that SGD is an important determinant of community structure. We thus have neither thorough SGD investigations with inferences about ecological responses nor detailed observations of microalgae with only an inferred linkage to SGD. Attempting to assess the role of SGD on microalgal dynamics is complicated by two factors. First, discharge occurs through the benthos, which in near-shore waters is the niche inhabited by benthic microalgae. The microphytobenthos (MPB) can be present at densities orders of magnitude higher than the phytoplankton and have repeatedly been shown to alter nutrient efflux. The role of the MPB as a sink for nutrients will depend on their growth rates, which are in turn largely driven by temperature and light availability. The second complicating factor is that SGD can be highly episodic and its nutrient content very variable. The effect of SGD on the phytoplankton assemblage may be due to nutrient delivery and/or to dilution (reduction in competition and grazing pressure) and altered residence times. The time-scales of SGD and community response are difficult to assess by standard sampling methods. This project will to investigate the link between SGD and microalgal dynamics in Little Lagoon, Alabama, a model system for such a study. In contrast to most near-shore environments, it is fully accessible; has no riverine inputs; and is large enough to display ecological diversity (c. 14x 0.75 km) yet small enough to be comprehensively sampled on appropriate temporal and spatial scales. The PIs have previously demonstrated that the lagoon is a hot-spot for toxic blooms of the diatom Pseudo-nitzchia spp that are correlated with discharge from the surficial aquifer. This project will use state-of-the-art techniques to assess variability in SGD, the dependence of benthic nutrient fluxes on MPB abundance and productivity, and the response of the phytoplankton to nutrient enrichment and dilution. The work will integrate multiple temporal and spatial scales and will demonstrate both the relative importance of SGD vs. benthic recycling as a source of nutrients, and the role of SGD in structuring the microalgal community.Broader Impacts: Although this project is geographically restricted, its findings should be far reaching. Groundwater-born nutrient enrichment is now normal where agriculture occurs over porous soils, including in New England, Maryland/Delaware, Florida, Alabama, likely Texas, Yucatan (Mexico), California, Korea, Japan, and the Netherlands etc. The likely dependence of coupling between SGD and phytoplankton composition is likely to be driven by temperature and the frequency/intensity of precipitation, both of which will change in the Northern Hemisphere, according to the IPCC. The phenomenon therefore has wide application. This project will provide training opportunities for three Ph.D. students and the findings will be incorporated into several courses: Physiological Ecology of Microalgae (MacIntyre), Global Biogeochemical Cycles (Mortazavi) and Environmental Radiochemistry (Burnett). Last, this project will build on the PI's active partnership with local citizens, members of the Little Lagoon Preservation Society (LLPS), in bi-weekly monitoring of water quality and microalgal community composition. Members of the PI's lab have presented talks at each of LLPS' quarterly meetings for the past 2 years. These are attended by local stakeholders, local and state political representatives, and members of the press, and have proved to be an effective means for outreach and education on eutrophication, HABs and hypoxia. The relationship has been reported on extensively in the local press and praised as exemplary in an editorial in the region's largest newspaper.

在过去的几十年中，许多研究表明，海底地下水出院（SGD）将大量的养分运送到全球河口和近岸海洋。到目前为止，SGD的地球化学和水文研究都没有表现出明显的生态作用。同时，对微藻社区动态的研究提出了SGD是社区结构的重要决定因素。因此，我们既没有针对生态反应的推断，也没有对微藻的详细观察，只有与SGD的链接有关。 试图评估SGD在微藻动力学上的作用是两个因素复杂的。 首先，通过底栖生物发生排放，在近岸的水域中，这是底栖微藻居住的利基市场。微植物本（MPB）可以以比浮游植物高的密度阶数来存在，并反复证明可以改变营养排出。 MPB作为营养成分的水槽的作用将取决于它们的生长速率，这反过来又由温度和光的可用性驱动。第二复杂因素是SGD可以高度发作，其营养含量非常可变。 SGD对浮游植物组合的影响可能是由于营养递送和/或稀释（竞争和放牧压力的降低）和停留时间改变。 SGD和社区响应的时间表很难通过标准抽样方法评估。 该项目将研究阿拉巴马州小泻湖的SGD和微藻动力学之间的联系，这是该研究的模型系统。与大多数近岸环境相反，它是完全可访问的。没有河流投入；并且足够大，可以显示生态多样性（c。14x0.75 km），但足够小，可以在适当的时间和空间尺度上进行全面采样。 PI先前已经证明，泻湖是硅藻伪nitzchia spp的有毒花朵的热点，与从表面含水层排出相关。 该项目将使用最先进的技术来评估SGD的可变性，底栖营养通量对MPB丰度和生产率的依赖性以及浮游植物对养分富集和稀释的反应。这项工作将整合多个时间和空间尺度，并将证明SGD与底栖回收作为养分的来源的相对重要性，以及SGD在构建微藻群落中的作用。尽管如此，该项目受到地理位置的限制，但其发现应遥遥无期。 现在，在多孔土壤上发生农业，包括在新英格兰，马里兰州/特拉华州，佛罗里达州，阿拉巴马州，可能是德克萨斯州，墨西哥（墨西哥），加利福尼亚，韩国，日本和荷兰的可能依赖的频率和荷兰之间的频率可能依赖于SGD和Phytoplank的频率，在多孔土壤上发生农业，包括新英格兰，马里兰州/特拉华州，可能据IPCC称，其中将在北半球发生变化。因此，该现象具有广泛的应用。 该项目将为三个博士提供培训机会。学生和发现将纳入几门课程：微藻（MacIntyre）的生理生态学，全球生物地球化学周期（Mortazavi）和环境放射化学（Burnett）。最后，该项目将基于PI与当地公民，小泻湖保护协会（LLP）的成员的积极合作，每两周一次监测水质和微藻社区组成。 PI实验室的成员在过去两年中在LLP的每季度会议上进行了会谈。当地利益相关者，地方和州政治代表以及新闻界成员都参加了这些活动，并被证明是富营养化，哈布斯和缺氧的宣传和教育的有效手段。该关系在当地媒体上广泛报道，并在该地区最大的报纸上的社论中称赞为典范。