This book presents methods for investigating the effects of aquatic environmental changes on organisms and the mechanisms involved. It focuses mainly on photosynthetic organisms, but also provides methods for virus, zooplankton and other animal studies. Also including a comprehensive overview of the current methods in the fields of aquatic physiology, ecology, biochemistry and molecular approaches, including the advantages and disadvantages of each method, the book is a valuable guide for young researchers in marine or aquatic sciences studying the physiological processes associated with chemical and physical environmental changes.