Landscape legacies in rivers: retrospective analyses of changes in ecosystem function across two centuries

河流景观遗产：两个世纪以来生态系统功能变化的回顾分析

• 批准号: 0953744
• 负责人: James Thorp
• 金额: $ 8万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0953744&HistoricalAwards=false
• 关键词: Landscape; legacies; rivers; retrospective; analyses

Natural variations in physical processes alter ecosystem structure and function, with the greatest impacts caused by natural and human disturbances that alter the control mechanisms defining how an ecosystem operates. The primary ecosystem driver in rivers relates to the timing, volume of water, and duration of high- and low-water periods as part of the natural flow regime. Ecological responses to altered control mechanisms can be linear or nonlinear, with the latter including somewhat unpredictable threshold responses where a community shifts abruptly to an alternative state of ecosystem function. Research on alternative states may determine whether some shifts to undesired alternative states are both predictable and reversible. Unfortunately, most studies of alternative stable states have been theoretical and very limited in time due to funding constraints. Our project circumvents these problems by using stable isotope analysis of museum specimens to determine how changes in the natural flow regime over a period of 100-150 years have altered food web complexity in medium to large rivers. Our initial project will focus on differences in food web complexity in the main channel, side channels, and backwaters of three geomorphically diverse areas of the Upper Mississippi River in response to altered flow regimes. Food webs will be constructed from real-time and museum samples of fish in multiple feeding groups. This project will also help alleviate the general dearth of knowledge about the functioning of rivers and will thus focus on ecosystems that have experienced relative declines in biodiversity far greater than those in the most affected terrestrial ecosystems of North America. This historical knowledge of effects of changing ecosystem drivers on functioning of river ecosystems is vital because we need to predict effects of future disturbances if, as expected, global climate changes and the need for more so-called green energy increases socioeconomic pressures to build more dams. The initial project takes the form of a proof-of-concept study and is thus limited in personnel and opportunities for the extensive broader impacts proposed for our full study. However, the project will include undergraduate assistants from two universities who will learn both field and lab techniques as well as gain a broader appreciation of the ecology of complex ecosystems.

物理过程的自然变化改变了生态系统的结构和功能，其中影响最大的是改变生态系统运作方式的控制机制的自然和人为干扰。河流中的主要生态系统驱动因素与作为自然水流状态一部分的高潮和低潮期的时间、水量和持续时间有关。改变控制机制的生态反应可以是线性或非线性的，后者包括某种程度上不可预测的阈值反应，其中一个社区突然转变为另一种生态系统功能状态。对替代状态的研究可以确定向不期望的替代状态的一些转变是否是可预测的和可逆的。不幸的是，大多数替代稳定状态的研究都是理论上的，并且由于资金限制，时间非常有限。我们的项目通过使用博物馆标本的稳定同位素分析来规避这些问题，以确定在100-150年的时间内，自然流动状态的变化如何改变中到大型河流的食物网复杂性。我们最初的项目将集中在食物网复杂性的差异，在主通道，侧通道，和回水的三个地貌多样性地区的密西西比河上游，以应对改变流态。食物网将从实时和博物馆的鱼类样本在多个喂养组。该项目还将有助于缓解对河流功能的普遍缺乏了解的情况，因此将重点关注生物多样性相对下降的生态系统，这种下降远远超过北美受影响最严重的陆地生态系统。这种关于生态系统驱动因素变化对河流生态系统功能影响的历史知识至关重要，因为我们需要预测未来扰动的影响，如果全球气候变化和对更多所谓的绿色能源的需求增加了建造更多水坝的社会经济压力。最初的项目采取概念验证研究的形式，因此在人员和机会方面受到限制，无法为我们的全面研究提出广泛的影响。然而，该项目将包括来自两所大学的本科生助理，他们将学习现场和实验室技术，并对复杂生态系统的生态学有更广泛的了解。