Sagot :
Answer:
1.Just like animals and humans living on land, animals that live in water need oxygen to survive. Oxygen from the atmosphere dissolves in river and lake water, and it is this oxygen that fish and other aquatic animals use to breathe.
2.Many, but not all, fish kills in the summer result from low concentrations of dissolved oxygen in the water. Fish, like all other complex life forms, need oxygen to survive. ... Other organisms use oxygen, too, including the algae that grow in the summer and bacteria that degrade organic matter.
3.Low dissolved oxygen (DO) primarily results from excessive algae growth caused by phosphorus. ... As the algae die and decompose, the process consumes dissolved oxygen. This can result in insufficient amounts of dissolved oxygen available for fish and other aquatic life.