Collaborative Research: MSA: The influence of temperature and resource supply on community size spectra in streams

合作研究：MSA：温度和资源供应对溪流中群落大小谱的影响

• 批准号: 2106067
• 负责人: Jeff Wesner
• 金额: $ 25.89万
• 依托单位: University of South Dakota Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2106067&HistoricalAwards=false
• 关键词: Collaborative; Research; MSA; influence; temperature

Humans rely on properly functioning freshwater ecosystems (e.g., streams, lakes, wetlands) for food, recreation, and drinking water. A major challenge in ecology is to understand how freshwater ecosystems will change in response to environmental disruptions. However, past efforts at measuring this change across large spatial scales are complicated by at least two challenges: 1) different places have different species, which makes it hard to compare across species when it comes to ecosystem function, and 2) collecting ecological information is extremely labor intensive, which makes it difficult to study ecological communities over space and time. This project solves those problems using cutting-edge ecological approaches. First, to overcome the limitations of species turnover, this project will measure ecosystem structure and function using animal body size distributions known as size-spectra (e.g., the relative abundance of large to small organisms), which are thought to be conserved across ecosystems regardless of species composition. Size spectra are an indicator of how efficiently energy is transferred from one organism to another in a food chain. Second, this project overcomes logistical limitations by using data already collected and curated from the National Ecological Observatory Network (NEON). Using NEON data, the researchers will analyze a large collection of size-spectra in streams over a wide range of environmental conditions to determine how stream temperature and nutrients influence freshwater ecosystems. This project is in the national interest because it provides a critical test of how freshwater ecosystems might respond to future temperature scenarios at macroecological scales. The researchers will also develop software that makes analysis of body size distributions freely available to the public and easier for ecologists to study in the future. Over 50 years of research reveals a common pattern across ecosystems in which abundance (N) declines with increasing body mass (M). The shape of this relationship is described by a power law, N ~ M(exp b), known as the abundance size-spectrum, and the exponent b varies in relation to changes in energy flow through the food web. The value of b is almost always negative, suggesting a remarkably consistent ecological pattern. However, climate change is expected to alter size-spectra, based in part on shifts in body size with temperature. Despite a seemingly simple relationship of body size and temperature, experimental and field studies demonstrate disparate results for size spectra-temperature relationships, finding positive, negative, and neutral shifts in size-spectra across temperature regimes. These studies largely consist of limited samples across relatively small spatial scales, making it difficult to predict how size-spectra varies with temperature at larger scales such as continents. In addition, deviations from theoretical predictions of the b-temperature relationship may be resolved by accounting for variation in resource supply, but the effect of resource supply at large scales is also unknown. This project uses statistical modeling to determine the influence of stream temperature and resource supply on stream size spectra exponents across a broad environmental gradient represented by a national monitoring network.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

人类依赖于正常运作的淡水生态系统（例如，河流、湖泊、湿地），用于食物、娱乐和饮用水。生态学的一个主要挑战是了解淡水生态系统将如何应对环境破坏。然而，过去在大空间尺度上测量这种变化的努力至少有两个挑战：1）不同的地方有不同的物种，这使得在生态系统功能方面很难进行跨物种的比较，2）收集生态信息是非常劳动密集型的，这使得很难在空间和时间上研究生态群落。该项目使用尖端的生态方法解决这些问题。首先，为了克服物种更替的局限性，该项目将使用被称为大小谱的动物身体大小分布来测量生态系统的结构和功能（例如，大型生物与小型生物的相对丰度），这些生物被认为在整个生态系统中得到保护，无论物种组成如何。大小谱是能量在食物链中从一个生物体转移到另一个生物体的效率的指标。其次，该项目通过使用已经从国家生态观测网络（氖）收集和管理的数据克服了后勤限制。利用氖数据，研究人员将分析各种环境条件下溪流中的大量尺寸谱，以确定溪流温度和营养物质如何影响淡水生态系统。该项目符合国家利益，因为它提供了一个重要的测试，淡水生态系统如何在宏观生态尺度上对未来的温度情景作出反应。研究人员还将开发软件，使公众可以免费获得体型分布的分析，并使生态学家在未来更容易研究。 50多年的研究揭示了生态系统中的一个共同模式，即丰度（N）随着体重（M）的增加而下降。这种关系的形状由幂律N ~ M（exp B）来描述，称为丰度大小谱，指数B随着通过食物网的能量流的变化而变化。B的值几乎总是负值，这表明生态模式非常一致。然而，气候变化预计会改变大小谱，部分原因是身体大小随温度变化。尽管身体大小和温度之间的关系看似简单，但实验和实地研究表明，大小谱与温度之间的关系存在差异，发现大小谱在温度范围内的正、负和中性变化。这些研究主要包括相对较小的空间尺度上的有限样本，因此很难预测尺寸谱如何随较大尺度（如大陆）的温度变化而变化。此外，b-温度关系的理论预测偏差可以通过解释资源供应的变化来解决，但大尺度资源供应的影响也是未知的。该项目使用统计建模来确定河流温度和资源供应对河流大小谱指数的影响，该指数跨越由国家监测网络代表的广泛环境梯度。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。