<span>The plant holds reserves of starches and sugars in its system during the times in which it has access to light. During periods of darkness, it will access these reserves if there are no other forms of light available or accessible.</span>
In a pond oxygen is gathered in two ways. One from the air or from the aquatic plants that live in the pond. Oxygen gets dissolved from these when mixed with air and water movement
I was looking for an answer and I found this. I hope this helps in some way.
Oxygen, carbon dioxide and your mom
