POWRE: Hydrogeology and Geochemistry of Streambeds in Karst Aquifers

9870423 wicks根据对河流下垫河床物质的研究，已经确定了不同的水文地质、地球化学和生态活动区（Rouch, 1988）。动物在间隙空间的生态组合是沉积物的水力传导率和间隙水的溶解氧浓度的函数。在洞穴溪流中，河床沉积物中存在间隙孔隙，但很少有研究人员研究了这些间隙中存在水生穴居动物的可能性。关于水生穴居人物种的生境偏好信息缺乏。一般认为，这类物种更喜欢开放水域、水池和河槽（Barr, 1968; Brown and Willis, 1984）。进行洞穴内生物计数的科学家假设，在视觉流检查中发现的个体数量等于存在的生物数量。Schubert（1993）表明南方洞穴鱼更喜欢居住在河床（砾石大小的基质，具有鱼类可以进入的空隙）的空隙空隙中，而不是在水柱中。如果首选栖息地在河床的间隙，那么在目视检查中计算的生物数量可能明显低估了存在的生物的真实数量。居住在间隙空间似乎可以提供躲避捕食者的住所，并获得食物，因为许多水生穴居物种都在觅食。本探索性项目要求：1。不同栖息地的水文地质环境是什么？水文地质环境将通过确定河床材料的水力导电性、孔隙度和粒度分布以及沿溪流的水力梯度来表征。孔隙空间中水的地球化学特征是什么？地球化学环境的特征是测定溶解氧和碳酸氢盐的浓度，以及测定间隙水的温度、pH值和Eh随深度的函数。流动的水和间隙水之间的交换率是多少？流动水和间隙水之间的交换速率将通过分析一个站点的流动水和间隙水的温度波动来确定。了解水生穴居物种居住的地方，以及这些地点的地球化学和水文地质制度，将有助于科学家们枚举种群，确定栖息地需求，并保护生物群。量化和模拟子通道地球化学和水文过程的能力对于提高我们对水生穴居物种栖息地需求的理解至关重要。这一探索性提案为描述三条喀斯特溪流的地球化学和水文栖息地的研究募集资金，这三条喀斯特溪流是四种水生穴居动物的栖息地。这项研究为首席研究员开辟了一条新的研究路线，并为确定水生穴居物种的地球化学和水动力环境迈出了第一步。这一探索性研究项目是将地球化学和水动力条件与水生穴居物种的生境要求联系起来的首次努力。

9870423WicksBased on research in streambed materials underlying rivers, distinct zones of hydrogeologic, geochemical, and ecological activities have been defined (Rouch, 1988). The ecotonal assemblage of animals in the interstitial space is a function of the hydraulic conductivity of the sediment and the dissolved oxygen concentration of the interstitial water. In cave streams, interstitial pores exist within the streambed deposits, yet few researchers have investigated the possibility that aquatic troglodytic species might reside in these interstitial spaces.Information is lacking regarding the habitat preferences of aquatic troglodytic species. It is generally assumed such species prefer open-water conditions, pools and riffles (Barr, 1968; Brown and Willis, 1984). Scientists conducting in-cave organism counts have assumed that the number of individuals found during visual stream inspections is equal to the number of organisms present. Schubert (1993) have shown that southern cavefish prefer to reside within the interstitial pore spaces of streambeds (gravel-sized substrate with interstitial spaces that the fish can enter) and not in the water column proper. If the preferred habitat is in interstitial spaces of the streambed, then the number of organisms that are counted during visual inspections may markedly underestimate the true number of organisms present. Residing in the interstitial spaces would appear to provide shelter from predation, and access to food, as many of the aquatic troglodytic species forage. This exploratory project asks:1. What is the hydrogeologic setting of the various habitats? The hydrogeologic setting will be characterized by determining the hydraulic conductivity, porosity, and grain size distribution of the streambed material and the hydraulic gradient along the stream reach.2. What is the geochemistry of the water in interstitial pore space? The geochemical setting will be characterized by determining the concentrations of dissolved oxygen and bicarbonate and by determining the temperature, pH, and Eh of the interstitial water as a function of depth.3. What is the exchange rate between the flowing water and the interstitial water? The exchange rate between the flowing water and the interstitial water will be determined by analyzing the fluctuations in the temperature of the flowing water and the interstitial water at one site. Understanding where the aquatic troglodytic species reside, and the geochemical and hydrogeological regimes of those locations, will aid scientists who need to enumerate populations, determine habitat requirements, and conserve the biota. The ability to quantify and model sub-channel geochemical and hydrological processes is critical to improving our understanding of the habitat requirements of aquatic troglodytic species. This exploratory proposal solicits funding for research that will describe the geochemical and hydrological habitat of three karst streams, which are the habitats for four aquatic troglodytic species. This research represents a new line of inquiry for the Principal Investigator and a first step in determining the geochemical and hydrodynamic environment of aquatic troglodytic species. This exploratory research project is the first effort to link the geochemical and hydrodynamic conditions to the habitat requirements of aquatic troglodytic species.