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The growth and biological acivity of aquactic organisms can be majorly influenced by changes in temperature.

Water temperature is the major factor determining how much dissolved oxygen there is in water. Cold water is able to hold more dissolved oxygen than warm water, and dissolved oxygen is essential for the survival of aquatic animals.

As well as the need for dissolved oxygen, aquatic animals also have preferred temperature ranges. If the temperature goes too far outside of this range for too long, it can cause a decrease in the number of species living in a waterway.

Water temperature is affected by:

  • depth
  • flow rate
  • amount of sunlight or shade
  • turbidity
  • season
  • time of day
  • run-off (e.g. stormwater that has flowed over hot surfaces in urban areas).