Collaborative Research: Interactive effects of temperature and nutrient supply on the structure and function of stream ecosystems

合作研究：温度和养分供应对河流生态系统结构和功能的交互影响

• 批准号: 1354624
• 负责人: Jonathan Benstead
• 金额: $ 45.8万
• 依托单位: University of Alabama Tuscaloosa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1354624&HistoricalAwards=false
• 关键词: Collaborative; Research; Interactive; effects; temperature

A lot of scientific effort is now being focused on how plants and animals will respond to a warming climate. This is critically important, but very difficult because there are many other global changes occurring at the same time. For example, humans have widely spread large amounts of nitrogen and phosphorus, which are important fertilizers. But what effects excess nutrients that are deposited mainly on land but then wash into aquatic ecosystems will have as the world warms is not clear. So studies are needed that examine how multiple global changes like these interact at the same time. The goal of this research project is to explore how freshwater ecosystems respond to warming and nutrient enrichment simultaneously. The research is important because nutrient enrichment may drastically alter the effects of warming on streams and rivers and so the results should be useful as society tries to adapt to warmer conditions. Results will also inform ecological theory that attempts to use basic principles for understanding how species and ecosystems may respond to global change. An education program will be an integral part of this project and will include the development of film documentaries, student podcasts, and the more traditional training of undergraduate and graduate students, as well as research technicians. This project will be conducted in a geothermally active region of southwestern Iceland, where streams exhibit a wide range in ambient temperature without significant differences in background chemistry that would otherwise influence results. The research team will use the differences in natural temperature between streams to examine how nutrient supply and temperature together influence the ecology of streams and rivers. The first objective is to quantify effects of warming and nutrients on the origin and fate of carbon and nitrogen (e.g., ecosystem productivity, nutrient uptake, and nitrogen-fixation). The team will then combine ecosystem-scale nitrogen and phosphorus additions with controlled streamside channel experiments to examine how the influence of warming on the ecology of streams and rivers is affected by nutrient supply, and whether short-term responses to warming differ from those observed in natural ecosystems over longer periods. Responses of these ecosystem-level processes should also shape how energy and materials flow through food webs from algae to trout. The second objective is to quantify the interactive effects of temperature and nutrients on the routes of energy and materials through river and stream food webs. Food web responses to nutrients between streams of varying temperatures will be tracked using a combination of stable (i.e., non-radioactive) isotope tracer additions, secondary production measurements, and flow food web analyses. This research will provide much needed information about how two dominant global change drivers, warming and nutrient enrichment, interact to influence biodiversity and ecosystem function in an important freshwater habitat.

目前，许多科学工作都集中在植物和动物如何应对气候变暖上。这非常重要，但也非常困难，因为同时还发生许多其他全球变化。例如，人类广泛施用了大量的氮和磷，它们是重要的肥料。 但随着世界变暖，主要沉积在陆地上但随后冲入水生生态系统的过量营养物质会产生什么影响尚不清楚。 因此需要进行研究来检验诸如此类的多个全球变化如何同时相互作用。 该研究项目的目标是探索淡水生态系统如何同时响应变暖和营养丰富。 这项研究很重要，因为营养丰富可能会极大地改变变暖对溪流和河流的影响，因此当社会试图适应变暖的条件时，研究结果应该是有用的。 研究结果还将为生态理论提供信息，生态理论试图利用基本原理来理解物种和生态系统如何应对全球变化。 教育计划将是该项目不可或缺的一部分，包括电影纪录片、学生播客的开发以及对本科生和研究生以及研究技术人员的更传统的培训。该项目将在冰岛西南部的地热活跃地区进行，该地区溪流的环境温度变化范围很大，背景化学成分没有显着差异，否则会影响结果。研究小组将利用溪流之间自然温度的差异来研究养分供应和温度如何共同影响溪流和河流的生态。第一个目标是量化变暖和营养物质对碳和氮的起源和归宿的影响（例如生态系统生产力、养分吸收和固氮）。然后，该团队将生态系统规模的氮和磷添加与受控的河边河道实验相结合，以研究养分供应如何影响变暖对溪流和河流生态的影响，以及对变暖的短期反应是否与在实验中观察到的不同。较长时期内的自然生态系统。 这些生态系统层面过程的反应也应该影响能量和物质如何通过食物网从藻类流向鳟鱼。第二个目标是量化温度和营养物质对河流和溪流食物网的能量和材料路径的相互作用影响。将使用稳定（即非放射性）同位素示踪剂添加、二次生产测量和流动食物网分析的组合来跟踪不同温度流之间的食物网对营养物的反应。这项研究将提供急需的信息，了解全球变化的两个主要驱动因素——变暖和营养富集——如何相互作用，从而影响重要淡水栖息地的生物多样性和生态系统功能。