DISSERTATION RESEARCH: Does a large detritus pool enhance ecosystem resilience in response to an episodic perturbation?

暴雨径流可以侵蚀和输送大量的沉积物和营养物质到湖泊。这种出口在美国中西部尤为明显，那里的大片农业留下了裸露的土壤，在暴风雨中很容易被冲走。在风暴期间，这些沉积物和营养物质大量涌入湖泊，可能会影响饮用水质量、娱乐机会以及商业和体育捕鱼。预计未来100年，美国中西部的风暴将在严重程度和频率上增加。这篇博士论文改进补助金将提供资金，以了解湖泊在这些变化的条件下将如何应对风暴。此外，该项目将直接支持一名博士生的研究，并将为本科生提供实践研究机会。这项研究将使用模拟湖泊大型风暴事件期间条件的重复水生中隔(5000升水箱)，通过实验研究风暴事件后湖泊生态系统弹性的影响因素。这项研究将回答三个一般性问题：(1)较大的碎屑池是否会加快湖泊在大型风暴事件后的恢复力(生态系统恢复所需的时间)？(2)大型风暴事件期间发生的沉积物和营养物质的增加如何影响湖泊恢复时间？以及(3)沉积物和营养物质的添加以及碎屑池的大小如何交互作用地影响湖泊的弹性？这项实验将包括对碎屑池大小、水力冲洗(一种减少藻类数量的物理干扰)以及添加沉积物和营养物质的操作。因子设计将被用来隔离影响大风暴事件后湖泊恢复的机制。了解这些因素是如何相互作用的，对于了解生态系统的复原力和有效管理湖泊和水库的水质至关重要。

Storm water runoff can erode and transport high levels of sediment and nutrients to lakes. This export is especially pronounced in the Midwestern U.S., where large areas of agriculture have left exposed soils that easily wash away during storms. These large pulses of sediments and nutrients to lakes during storms can affect drinking water quality, recreational opportunities, and commercial and sport fishing. It is expected that storms in the Midwestern U.S. will increase in severity and frequency over the next 100 years. This Doctoral Dissertation Improvement Grant will provide funds to understand how lakes will respond to storms under these changing conditions. In addition, this project will directly support the research of one doctoral student, and will provide hands-on research opportunities for undergraduate students.This research will experimentally examine what factors contribute to lake ecosystem resilience following storm events, using replicated aquatic mesocosms (5000 liter tanks) that simulate conditions during large storm events in a lake. This research will answer three general questions: (1) Do larger detritus pools speed lake resilience (the time necessary for ecosystems to recover) following large storm events? (2) How do additions of sediment and nutrients that occur during large storm events affect lake recovery time? and (3) How do additions of sediment and nutrients and detritus pool size interactively affect lake resilience? The experiment will include manipulations of detritus pool size, hydraulic flushing (a physical disturbance that reduces the amount of algae), and addition of sediment and nutrients. A factorial design will be used to isolate the mechanisms that influence lake recovery following large storm events. Understanding how these factors interact is essential to understanding ecosystem resilience and for effective management of water quality in lakes and reservoirs.