What effect does higher water temperature have on dissolved oxygen levels in water?

Higher water temperature decreases dissolved oxygen levels in water. As the temperature of water rises, the solubility of oxygen decreases, which means that warm water can hold less dissolved oxygen compared to cold water. This is particularly important in aquatic environments since many organisms, such as fish and aquatic invertebrates, rely on dissolved oxygen for respiration. When water temperatures increase—whether due to natural factors or human activities—the oxygen availability diminishes, potentially leading to stressful conditions for aquatic life.

The other scenarios, such as increasing dissolved oxygen, having no change, or causing oxygen saturation, do not accurately reflect the relationship between temperature and oxygen solubility. Understanding this relationship is crucial for wastewater treatment operators and environmental scientists, as it impacts water quality management and the health of aquatic ecosystems.