What effect does algae in surface water have on dissolved oxygen levels during the day?

The presence of algae in surface water has a positive effect on dissolved oxygen levels during the day due to the process of photosynthesis. Algae, like other aquatic plants, utilize sunlight to convert carbon dioxide and water into glucose and oxygen. During daylight hours, when photosynthesis occurs, algae release oxygen as a byproduct. This process significantly increases the concentration of dissolved oxygen in the water, especially in well-lit areas where algae growth is abundant.

In contrast, while algae can contribute to increases in dissolved oxygen during the day, the situation may change at night or under certain conditions, such as when algal blooms occur and when respiration rates exceed photosynthesis. Therefore, understanding the dynamics of algae's role in oxygen production is important for water quality management and assessing the ecosystem's health.