Aquatic organisms rely on the presence of oxygen in streams. In water, oxygen is in a dissolved form. Water temperature and altitude, time of day, and seasons can all affect the amount of dissolved oxygen. Oxygen is both produced and consumed in a stream. The presence of aquatic plants also affects dissolved oxygen concentrations.
Green plants release oxygen underwater during photosynthesis.
Maximum amounts of DO are produced with the energy of the late afternoon sun. By early morning, the same plants may have taken up the oxygen, making levels of DO lowest at this time. The pH of a stream affects the ability of plants and wildlife to function and live. Neutral pH is 7.0. A wide variety of aquatic animals prefer a range of 6.5-8.0 pH. Turbidity Turbidity is a measure of water clarity.