Groundwater flooding: Groundwater community recovery following an extreme recharge event.

今年冬天（2013-14年）是英国有记录以来最潮湿的一年，导致地下水位极高，地下水泛滥，特别是在白垩含水层。洪水和水通过含水层的运动强度异常高，预计将导致包括碳在内的营养物浓度发生变化。我们认为，这些变化将对地下水生态系统产生重大影响，除化学和物理环境外，地下水生态系统还包括微生物生物膜、微型动物（如原生动物、轮虫）和以桡足类和Niphargus（盲虾状动物）等甲壳类动物为主的宏观无脊椎动物。大多数地下水生物都是这个栖息地所特有的，在英国，已经存在了数百万年。它们介导氮循环等过程，从而影响饮用水重要来源的质量。我们认为，在洪水期间，由于稀释，营养物质供应最初会减少，流速会增加，可能会从沉积物中剥离微生物生物膜和相关的微型动物，并将较大的生物体驱逐到水流中。这将导致每一营养级生物量的初步减少，但不会改变生物量金字塔的总体形状。我们还预计生态系统呼吸和物种和/或功能多样性在洪水期间会很低。当洪水结束时，我们认为微生物生物膜、原生动物和小型后生动物会迅速恢复，因为它们繁殖迅速，但较大的动物如果找不到躲避洪水的避难所，恢复会较慢。这可能导致生物质金字塔形状的变化。我们将通过跟踪地下水生态系统在空间和时间上的恢复来测试这些想法。我们将通过收集样本来测量食物供应（溶解有机碳和其他营养物质），计数和识别地下水生态系统的居民，并通过测量呼吸率和微生物活动来确定生态系统功能如何变化。我们将在七个月的时间里每隔两周在两个独立的被洪水淹没的白垩含水层中收集样本，以便我们能够监测社区的变化;我们预计这些变化会很快。我们将使用专门的设备来测量微生物呼吸，并计算最小的生物体（细菌）。这一极端事件是一个非常重要的案例研究，因为它将为未来的极端事件提供一个基线，（如洪水和干旱），使我们能够比较地下水生态系统与其他水生生态系统对压力源的反应。我们希望利用本项目收集的数据申请更大的赠款，这些拨款申请的可能主题包括将这项紧急拨款产生的数据与实验室实验相结合，使我们能够计算不同地下水组合的程度。（例如，有或没有大型动物）能够代谢溶解的有机碳/营养物负荷，从而为英国提供具有重大生态和经济影响的有效水质生态系统服务。

This winter (2013-14) has been the wettest in the UK since records began resulting in extremely high groundwater levels and very extensive groundwater flooding, particularly in chalk aquifers. The exceptionally high intensity of flooding and water movement through the aquifers is expected to result in changed nutrient concentrations, including carbon. We think that these changes will have major effects on the groundwater ecosystem which, in addition to the chemical and physical environment, comprises microbial biofilms, microfauna (e.g. Protozoa, rotifers), and macroscopic invertebrates dominated by crustaceans such as copepods and Niphargus (blind shrimp-like animals). Most groundwater organisms are unique to this habitat and, in the UK, have been present for many millions of years. They mediate processes such as nitrogen recycling and thus they impact the quality of a vital source for drinking water. We think that during flooding, nutrient supplies will initially decrease due to dilution and that flow rates will increase, potentially stripping microbial biofilms and associated microfauna from the sediments and dislodging larger organisms into the water flow. This will lead to an initial reduction in biomass at each trophic level although it will not alter the overall shape of the biomass pyramid. We also expect ecosystem respiration and species and/or functional diversity to be low during flooding. When the flood ends we think that microbial biofilms, protozoa and small metazoa will recover quickly because they reproduce rapidly but that larger animals will recover more slowly if they cannot find shelter from the flood. This may result in a change in shape of the biomass pyramids. We will test these ideas by tracking the recovery of the groundwater ecosystem through space and time. We will do this by collecting samples to measure the food supply (dissolved organic carbon and other nutrients), count and identify the inhabitants of the groundwater ecosystem and also determine how ecosystem function changes by measuring respiration rates and microbial activity. We will collect samples in two separate flooded chalk aquifers at fortnightly intervals over a seven month period so that we can monitor changes in the community; we expect these to be rapid. We will use specialised equipment to measure microbial respiration and count the smallest organisms (bacteria). This extreme event permits a uniquely important case study because it will provide a baseline against which future extreme events (e.g. flooding and drought) in groundwaters can be measured and will enable us to compare the responses of groundwater ecosystems to stressors with those of other aquatic ecosystems.We hope to use the data collected in this project to apply for larger grants, possible topics for these grant applications include combining data generated in this Urgency grant with laboratory experiments that will enable us to calculate the extent to which different Groundwater assemblages (e.g. with or without macrofauna) are able to metabolise dissolved organic carbon/ nutrient loadings and thus, provide effective water quality ecosystem services of substantial ecological and economic impact to the UK.