This volume aims to review and present research on acid waters and their effects on aquatic animals. Starting initially with the environment in order to assess why the problems have arisen in particular areas, the volume then deals with field and survival studies on invertebrates and vertebrates and examines the extent of the biological problem and the attempts which have been made to relate water quality and the susceptibility of animals. Major advances in this area have included the realization that declining populations are often the result of acid waters and their interactions with traces of other ions and that these situations produce the most severe physiological problems. The natural progression of environmental and field studies, toxicity and survival tests provide the background information for the physiological studies which follow. These form the major component of the book and they seek to analyse the toxic effects of acid waters and trace metals on acid-base balance, respiration, ionic balance together with cardiovascular and endocrinological effects.