What effect will algae have on dissolved oxygen during the day?

Algae contribute to the increase of dissolved oxygen (DO) in water during the day through a process known as photosynthesis. During daylight hours, algae and aquatic plants utilize sunlight to convert carbon dioxide and water into glucose and oxygen. This oxygen is released into the surrounding water, thereby raising the levels of dissolved oxygen.

This positive effect on DO levels is particularly significant in well-lit and nutrient-rich environments, where algal blooms may occur. These blooms can substantially enhance the overall oxygen availability in the water during sunny days.

At night, a different process occurs where algae, along with other organisms, respire and consume oxygen, which would lead to a decrease in DO levels. However, the question specifically addresses the daytime effect, which is the increase in dissolved oxygen levels due to the photosynthetic activity of algae. Thus, the correct answer reflects the role that algae play during the day in oxygen production.