What effect does algae have on pH levels during the night?

During the night, algae undergo a process known as respiration in the absence of sunlight. This process consumes oxygen and releases carbon dioxide, which can lead to a decrease in pH levels in the surrounding water. The increased concentration of carbon dioxide reacts with water to form carbonic acid, which subsequently lowers the pH. This phenomenon is commonly observed in aquatic systems that have high levels of algal biomass, as the metabolic activities of the algae significantly influence the chemical balance of the water. Thus, the correct answer reflects this biological process and the resulting impact on pH levels during nighttime.