How does algae affect dissolved oxygen levels during the day and night?

Algae play a significant role in the dynamics of dissolved oxygen (DO) levels in aquatic ecosystems, influenced by their process of photosynthesis and respiration. During the day, algae undergo photosynthesis, a process that uses sunlight to convert carbon dioxide and water into glucose and oxygen. This production of oxygen leads to an increase in dissolved oxygen levels in the water, which is beneficial for aquatic life.

However, at night, the absence of sunlight halts photosynthesis, and algae, like all living organisms, continue to respire. During respiration, they consume oxygen and release carbon dioxide. This respiration process results in a decrease in dissolved oxygen levels at night. Consequently, the daily cycle of algae significantly raises dissolved oxygen levels during daylight hours and lowers them during the night, making the observed pattern—that of increasing DO during the day and decreasing it at night—accurate.

This understanding is crucial for water operators as it can influence water quality monitoring and management strategies, particularly in maintaining a healthy aquatic environment for fish and other organisms that rely on adequate oxygen levels.