dissolved oxygen

Dissolved oxygen is the measure of the oxygen in the water. This is important for marine animals to breathe. D.O. can get into water by waves or something that comes
in contact with the water and lets the air mix with the water. It is important to measure D.O. because we need to know how the water's oxygen trend affect the marine
animals. For example, if you have a fish in a bowl with a small opening and there is no movement on the surface of the water, the D.O. cannot mix with the air so the fish will die.