Climate change worsens oxygen depletion, reshaping growth, reproduction, and species distributions in aquatic ecosystems. Climate change and deoxygenation are among the most urgent threats to our planet's oceans, rivers, and lakes, and the animals that inhabit them. The impact of warming waters and declining oxygen levels includes shifts in individual growth and reproduction, as well as changes in population dynamics and species distribution. These developments demand action, but to act effectively it is important to understand the general mechanisms that drive these trends.This book presents a theoretical framework for explaining how warming waters and deoxygenation affect the growth and reproduction of fish and other water-breathing animals. Despite their diversity, these organisms share fundamental life-history traits shaped by common physiological mechanisms and constraints. We address these mechanisms within the Gill-Oxygen Limitation Theory (GOLT), which explains growth and reproduction in terms of oxygen uptake capacity. Building on decades of research, this book outlines the principles of GOLT and explores its wide-ranging applications in ecology, physiology, and reproductive biology.

By presenting this unifying framework, the book provides a foundation for more effective responses to the current crisis in our planet's waters.