Aquatic deoxygenation poses significant risks to marine and freshwater ecosystems, disrupting biological and chemical processes that regulate Earth's climate. It threatens aquatic life, including fish, sharks, and microscopic organisms, and indirectly impacts marine mammals by altering their prey and habitats. Human-induced factors such as warming, nutrient pollution, and changes in water ventilation are primary drivers of this oxygen loss. The study warns that these disruptions could lead to cascading effects on biodiversity, food webs, and climate stability, making mitigation efforts critical for planetary health.