Ocean acidification is the process whereby seawater becomes less alkaline (or more acidic). It is a concern to Congress because of the potential harm ocean acidification may cause to marine resources, and resource dependent industries and communities. The chemistry of the Earth's oceans is changing as increasing amounts of anthropogenic carbon dioxide from the atmosphere dissolves into the water. The intent of this book is to guide research and monitoring investments that will improve our understanding of ocean acidification and its potential impacts on marine species and ecosystems. It will further the development of adaptation and mitigation strategies to conserve marine organisms and the resources and services provided by the ecosystems in which they live.