Dissertation Research: Ecosystem scale abiotic and biotic drivers of food web structure in deep phreatic aquifers

论文研究：深层潜水层食物网结构的生态系统规模非生物和生物驱动因素

• 批准号: 1210270
• 负责人: Benjamin Schwartz
• 金额: $ 1.5万
• 依托单位: Texas State University - San Marcos
• 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: 2012-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1210270&HistoricalAwards=false
• 关键词: Dissertation; Research; Ecosystem; scale; abiotic

Karst aquifers are sources of groundwater for human use, are an integral component of the water cycle, and may contain diverse microbial, invertebrate, and vertebrate communities. Many karst aquifers are threatened by groundwater extraction and contamination, but relatively little is known about their community structure, ecosystem function, or biogeochemical cycling. This research, on the Edwards Aquifer of south-central Texas, will address links between hydrogeology and geochemistry, the distribution of organic matter, and the trophic structure of groundwater communities. Specific issues that will be addressed will include the ways that hydrology and geochemistry affect the spatial and temporal distribution of chemolithoautotrophic and photosynthetic organic matter and utilization by groundwater species, whether biodiversity in groundwater habitats is supported by resource partitioning, and whether the prevailing paradigm of truncated trophic structure in subsurface habitats is supported by isotopic data. These issues will be addressed by sampling across geochemical gradients in the freshwater and saline portions of the aquifer. Methods will include inorganic and organic geochemical characterization of groundwater, geospatial analysis of geochemical data, stable isotope analyses, and morphometric analyses of invertebrates. Preliminary results show that organic matter produced both by plants, using sunlight, and by microbes that derive energy from redox reactions involving inorganic substrates (chemolithoautotrophs) is utilized by invertebrates, and both types of organic matter are distributed unevenly within the aquifer, being controlled by the movement of water (photosynthetic matter being prevalent near recharge features) and geochemistry (chemolithoautotrophic production occurring where fresh and saline groundwaters mix). This project will have substantial societal importance because it directly relates to water quality and the maintenance of biodiversity in ecosystems that are intensively managed for human use. The project also will provide field and laboratory opportunities for students, including Hispanics and women employed or enrolled as graduate students in the PIs laboratory.

岩溶含水层是人类使用的地下水源，是水循环的一个组成部分，可能含有多种微生物、无脊椎动物和脊椎动物群落。许多喀斯特含水层受到地下水开采和污染的威胁，但对其群落结构、生态系统功能或生物地球化学循环知之甚少。这项研究针对德克萨斯州中南部的爱德华兹含水层，将探讨水文地质学和地球化学、有机质的分布以及地下水群落的营养结构之间的联系。将要解决的具体问题包括水文学和地球化学如何影响化学自养和光合有机物的空间和时间分布以及地下水物种的利用，地下水生境的生物多样性是否得到资源分配的支持，以及截断的普遍范式是否存在。地下生境的营养结构得到同位素数据的支持。这些问题将通过对含水层淡水和盐水部分的地球化学梯度进行采样来解决。方法将包括地下水的无机和有机地球化学表征、地球化学数据的地理空间分析、稳定同位素分析和无脊椎动物的形态分析。初步结果表明，植物利用阳光产生的有机物，以及通过涉及无机底物（化学自养生物）的氧化还原反应获取能量的微生物产生的有机物均被无脊椎动物利用，并且两种类型的有机物在含水层内分布不均匀，受控于水的运动（补给特征附近普遍存在光合物质）和地球化学（淡水和咸水地下水混合时发生化能自养生产）。该项目将具有重大的社会重要性，因为它直接关系到供人类使用的集约管理生态系统中的水质和生物多样性的维护。该项目还将为学生提供现场和实验室机会，包括在 PI 实验室就业或注册为研究生的西班牙裔和女性。