Oxygen Demand Oxygen is a natural component in all bodies of water, and it is needed by all aquatic plant and animal life. Oxygen is needed by the microorganisms that play an important role in cleansing polluted streams by breaking down complex organic pollutants into simple and harmless chemicals. However, the more polluted a stream, the more the microorganisms and other aquatic life have to compete for the oxygen dissolved in the water. Thus, high levels of pollution cause high levels of oxygen demand and may cause such dramatic results as fish kills. Acidity Runoff from soils with a high acid content can increase the acidity of streams and lakes, which may affect aquatic life.
Acid rain can also increase water acidity.
Many of New Jersey's bodies of water are naturally acidic because of the particular make-up of New Jersey's soil and vegetation, but further increases can disrupt natural biochemical processes in stream life. Physical Habitat Alteration Activities such as construction, dredging, channeling and filling in of streams and wetlands can have a serious impact on aquatic life. When wetlands are destroyed, their ability to filter pollutants, nutrients and sediments is eliminated. When the sediment in the stream bed is removed or disturbed, the large populations of microorganisms that help the stream to cleanse itself may be sharply reduced or eliminated. Other aquatic life is also usually disrupted by habitat changes and may disappear at least for a period of time.