Why is Dissolved Oxygen important?

Document ID

Document ID TE2855

Published Date

Published Date 27/05/2017
Question
Why is Dissolved Oxygen important?
Summary
Importance of Dissolved Oxygen
Answer
Dissolved oxygen is necessary to many forms of life including fish, invertebrates, bacteria, and plants. These organisms use oxygen in respiration, similar to organisms on land. Fish and crustaceans obtain oxygen for respiration through their gills, while plant life and phytoplankton require dissolved oxygen for respiration when there is no light for photosynthesis. The amount of dissolved oxygen needed varies from creature to creature. Bottom feeders, crabs, oysters and worms need minimal amounts of oxygen (1-6 mg/L), while shallow water fish need higher levels (4-15 mg/L). Microbes such as bacteria and fungi also require dissolved oxygen. These organisms use DO to decompose organic material at the bottom of a body of water. Microbial decomposition is an important contributor to nutrient recycling. However, if there is an excess of decaying organic material (from dying algae and other organisms), in a body of water with infrequent or no turnover (also known as stratification) , the oxygen at lower water levels will get used up quicker.