Collaborative Research: Effects of Flow Regime Shifts, Anticendent Hydrology, Nitrogen Pulses and Resource Quantity and Quality on Food Chain Length in Rivers

合作研究：流态变化、前期水文、氮脉冲以及资源数量和质量对河流食物链长度的影响

• 批准号: 1457689
• 负责人: Tamara Harms
• 金额: $ 46.1万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1457689&HistoricalAwards=false
• 关键词: Collaborative; Research; Effects; Flow; Regime

The pattern of water flow in a river can affect the abundance of plants and animals and the food web that supports fisheries. Severe floods that scour the riverbed can potentially displace or kill plants and animals, however, little is known about how floods (or droughts) or the timing of these across years affects the complexity and diversity of food webs. Some work suggests that river flow is a stronger determinant than the quantity of plant production on the flow of energy through the food web, but little is known about how the quality of plant food affects food chains and biodiversity. The study will provide fundamental information on how the timing of floods and droughts across years influences water quality (nitrate inputs to rivers), primary production, and the production of animals higher in the food web, such as fish. The researchers will produce a synthesis of research in hydrology and ecology to improve the management of arid land rivers. This work will reach across fundamental knowledge to education, from kindergarten to graduate levels. The project will have numerous broader impacts including training of several undergraduates, graduate students, and a postdoc. Researchers will work with a non-profit group to integrate project findings into an existing citizen science program on river drying sponsored by The Nature Conservancy, and develop an environmental education program for grades K-5. Finally, the research team will establish an innovative open source, distributed graduate seminar on application of statistical methods in ecology.Researchers will study streams spanning a gradient in the timing of rainfall to examine the role of changing hydrologic regimes in altering nitrogen supply, energy supply and food web structure in arid land streams. This proposal will: 1) Quantify the effect of food quality, energy supply and energetic efficiencies on trophic structure, 2) Quantify the effects of time between floods on stimulation of plant production and trophic structure, and 3) Quantify the effect of changes in flow regime on trophic structure via direct mortality, shifts in plants at the base of the food web, and the structure of the food web. Proposed research activities include characterization of the hydrologic regime, analysis of food webs across a hydroclimate gradient, and manipulation of nitrogen supply. Extreme event statistics and spectral analyses will characterize properties of flood intervals and flow regime shifts across 12 study sites spanning a gradient in timing of rainfall and hydrologic variation (monsoon vs. winter precipitation dominance) in Arizona. Derived hydrologic metrics will be used in combination with measures of ecosystem metabolism, N supply, secondary consumer energetic efficiencies, resource stoichiometry, and the proportion of autochthonous energy sources as predictor variables of food chain length and trophic structure to understand the mechanisms linking energetics and hydrology to food chain length. This comparative study includes 12 streams within the same biogeographic province that feature an algal-dominated food source and similar ecosystem size (1st-3rd order streams). Additionally researchers will conduct a nitrogen enrichment experiment in 6 streams to disentangle the indirect effects of water flow on nitrogen cycling versus the direct effects on plants and animals.

河流中的水流模式会影响植物和动物的丰富性以及支持渔业的食物网。搜寻河床的严重洪水可能会取代或杀死动植物，但是，多年来洪水（或干旱）或这些时机如何影响食物网的复杂性和多样性。 一些工作表明，河流流量比通过食物网的能量流的植物产量数量更强大，但是关于植物食物的质量如何影响食物链和生物多样性，知之甚少。这项研究将提供有关多年洪水和干旱的时间的基本信息，如何影响水质（对河流的硝酸盐输入），初级生产以及食物网中较高的动物的生产，例如鱼类。 研究人员将生成水文学和生态学研究的综合，以改善干旱河流的管理。 从幼儿园到研究生水平，这项工作将跨越基本知识到教育。 该项目将产生许多更广泛的影响，包括对几名大学生，研究生和博士后的培训。研究人员将与一个非营利组织合作，将项目的发现纳入由Nature Consermancy赞助的河流干燥计划的现有公民科学计划，并为K-5年级制定环境教育计划。最后，研究团队将建立一个创新的开源，分布式研究生研讨会有关统计方法在生态学中的应用。研究人员将研究跨越降雨时间梯度的流，以研究改变水文制度在改变氮气供应，能源供应，能源供应，干旱土地上的食物网络结构中的作用。 该提议将：1）量化食物质量，能源供应和能量效率对营养结构的影响，2）量化洪水之间时间对植物生产和营养结构刺激的影响，以及3）量化流动状态变化对营养结构的变化对营养结构的影响，通过直接死亡率，通过食物网络和食物网络的植物中的植物转移和食物网络的植物转移。 拟议的研究活动包括对水文制度的表征，对氢化气候梯度的食物网的分析以及对氮供应的操纵。极端的事件统计和光谱分析将表征洪水间隔的特性和在亚利桑那州降雨和水文变化时机（季风与冬季降水优势）的12个研究地点的流动状态变化。衍生的水文指标将与生态系统代谢，n供应，二级消费者能量效率，资源化学计量计量以及自动能源能源的比例相结合，将自动链变量作为食物链长度和营养结构的预测变量，以理解与食品链长度相关的机制。这项比较研究包括在同一生物地理省内的12个流，这些流具有藻类为主导的食物来源和类似的生态系统大小（1st-3rd阶次流）。此外，研究人员将在6个流中进行氮富集实验，以消除水流对氮循环的间接影响，而不是对动植物的直接影响。