Collaborative Research: Linking ion transport, energetics and species distributions in freshwater ecosystems

以盐度来衡量，这个国家的溪流和湖泊正变得越来越咸。这些变化有些与当地人类活动有关，有些则与更广泛的气候变化有关。由于许多水生生物在低盐度环境中进化并需要低盐度环境，因此预计盐度的增加将产生重要影响。生态学家报告说，盐度的增加对一些水生生物（例如，水生昆虫，如蜉蝣，这是本项目的重点）有不利影响，这些生物在生态上很重要，是鱼类和鸟类的主要食物来源。因此，盐度的适度增加可能极大地影响淡水生态系统的生物多样性和功能。该项目旨在更好地了解不同水生昆虫物种在不同盐度水域中茁壮成长的能力如何以及为什么会有所不同。该研究将促进对盐度影响水生昆虫代谢、生长和生存的生理机制的理解，并最终影响它们的分布和丰度。项目成果将有助于地方、部落、州和联邦水资源机构及其成员和利益相关者更好地解释水生昆虫的监测数据，这些数据被广泛用作水质和生态条件的指标。至少有三名研究生和几名本科生研究人员将在该项目中得到支持和培训，调查人员将为K-12课程的发展做出贡献，这些课程与水质和生态生理学有关。该项目将把一种新的蜉蝣模型物种暴露在短期和长期的盐度梯度中，以确定基因表达模式、氧气消耗、血淋巴化学和鳃生理如何与健康指标联系起来。通过比较方法，研究人员将验证这样一种假设，即在稀释环境中离子吸收的效率和在富含离子的环境中抑制过量离子吸收的能力是形成盐度生态位的关键渗透调节特征。研究人员进一步假设，离子运输的能量成本与温度相互作用，影响生长、繁殖力和死亡率，从而确定物种特有的盐度生态位，这可以从野外调查数据的生态位分析中观察到。这项研究将极大地促进对盐度自然变化和人为引起的盐度变化如何在一个日益咸化的世界中促进生物性能和物种分布的理解。通过整合不同层次的生物组织（基因到生物多样性模式）以及实验室和野外工作，该项目将显著促进生理学和宏观生态学的综合。该项目还将有助于建立和评估一种有前途和需要的模式水生昆虫物种，并将为了解不同分类群之间的渗透调节差异提供基础，这将为利用水生昆虫作为环境变化的生态指标提供信息。研究生和本科生实习生将得到支持，高中教师将进行夏季研究并开发相关课程，将开发和测试综合水质科学、管理和政策方面的K-12科学课程，并将为联邦和州机构举办公共宣传讲习班。该奖项反映了美国国家科学基金会的法定使命，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。

The Nation's streams and lakes are growing increasingly salty, as measured by salinity. Some of these changes are associated with local human activities, and some are associated with broader climate changes. Increases in salinity are expected to have important impacts because many aquatic organisms evolved in and require low-salinity environments. Ecologists report that increases in salinity adversely affect some groups of aquatic organisms (e.g., aquatic insects such as mayflies, a focus of this project) that are ecologically important and serve as a primary food source for fishes and birds. Thus, modest increases in salinity could greatly affect both the biodiversity and functioning of freshwater ecosystems. This project is designed to better understand how and why different aquatic insect species vary in their ability to thrive in waters of different salinity. The research will advance understanding of the physiological mechanisms by which salinity affects the metabolism, growth, and survival of aquatic insects, and, ultimately, their distributions and abundance. Project results will help local, tribal, state, and federal water resource agencies and their constituents and stakeholders better interpret monitoring data on aquatic insects, which are widely used as indicators of water quality and ecological conditions. At least three graduate students and several undergraduate researchers will be supported and trained in the project, and the investigators will contribute to K-12 curriculum development related to water quality and ecological physiology.The project will expose a new mayfly model species to short-term and long-term salinity gradients to establish how gene expression patterns, oxygen consumption, hemolymph chemistry, and gill physiology link to measures of fitness. Using comparative methods, the researchers will test the hypothesis that the efficiency of ion uptake in dilute environments and the ability to curtail excessive ion uptake in ion-rich environments are key osmoregulatory characteristics that can shape salinity niches. The investigators further hypothesize that the energetic costs of ion transport interact with temperature to influence growth, fecundity, and mortality to define species-specific salinity niches, the expression of which in nature can be observed from niche analyses of field survey data. The study will significantly advance understanding of how both natural variation in salinity and human-induced changes in salinity contribute to organismal performance and species distributions in an increasingly salty world. By integrating different levels of biological organization (genes to biodiversity patterns) and laboratory and field work, the project should significantly advance the synthesis of physiology and macroecology. The project will also help establish and evaluate a promising and needed model aquatic insect species, and will provide foundational understanding of osmoregulation differences across taxa that will inform the use of aquatic insects as ecological indicators of environmental change. Graduate and undergraduate student trainees will be supported, high-school teachers will conduct summer research and develop relevant curricula, K-12 science curricula that integrate science, management, and policy aspects of water quality will be developed and tested, and public outreach workshops will be held for federal and state agencies.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.