In aerobic ponds, how is dissolved oxygen distributed?

• A. DO distributed throughout, may be provided by algae
• B. DO distributed unevenly
• C. DO is zero at surface
• D. DO is only at bottom

Answer: (A)

In aerobic ponds, dissolved oxygen is distributed throughout the water column because surface exchange with the air and mixing from wind and water movement continually supply and spread oxygen. Photosynthesis by algae adds oxygen during daylight, helping maintain DO at various depths. This means oxygen isn’t confined to the surface or bottom; it should be available throughout the pond, with algae contributing to higher DO during daylight. That’s why the statement that DO is distributed throughout and may be provided by algae best describes the situation. If it seemed uneven, or if DO were zero at the surface or only at the bottom, that would indicate poor mixing or anaerobic conditions, which isn’t typical for a properly functioning aerobic pond.