"Over the next several years, the Environmental Protection Agency's (EPA's) Global Change Research Program within the Office of Research and Development (ORD) will conduct a series of case studies in different regions of the United States to evaluate potential changes in aquatic ecosystems as a result of global stressors. Aquatic ecosystems include inland surface water (lakes, rivers, and streams); wetlands; near-coastal waters (tidal rivers, estuaries, and near-shore waters); and coral reefs. Global stressors of concern include climate change and climate variability, ultraviolet (UV) radiation, and the development of land and water resources. A primary interest of the case studies planned by EPA is to understand effects of global stressors on the ecosystem services provided by aquatic resources and their supporting habitats. Ecosystems services are the physical and biological functions performed by natural resources and the human benefits derived from those functions. This peer-reviewed contractor report, prepared by Stratus Consulting, describes and assessment framework designed to help case study researchers collect, organize, analyze and communicate to diverse stakeholders relevant ecological information on the effects of global stressors on aquatic ecosystems. The framework is intended to ensure that the case studies conducted by EPA's Global Change Research Program provide a comprehensive evaluation of the potential consequences of global stressors for both aquatic resources and the services they provide."--Background.