Water temperature plays an important role in water quality assessment.
Water temperature is an integral part of the web that exists amongst the six WAV water quality parameters. If you have visited WAV's dissolved oxygen and biotic index web pages, then you know that warmer water holds less dissolved oxygen than cold water, thus temperature can dictate what types of organisms can survive in a waterbody.
Additionally, with warmer water, metabolic rates are sped up, allowing for quicker plant growth and animal feeding, and higher respiration rates. Increased respiration rates, and decay of the increased numbers of organisms can lower dissolved oxygen concentrations further.
With increased turbidity, the water temperature will rise because suspended particles within the water absorb heat from sunlight.
Temperature can also directly affect survival of aquatic organisms:
Organisms need fairly stable temperatures for survival. For instance, brook trout require waters to be in the range of 55 to 65 degrees Fahrenheit (12.8 to 18.3 degrees Celsius) to survive. Other organisms, such as carp can survive in waters with higher temperatures. Organisms are generally adapted to seasonal changes in water temperature or levels. For instance, by emerging as adults, insects avoid warmer temperatures or drought conditions in the stream, and their eggs may be resistant to low dissolved oxygen levels. If a stream is subject to a large or abrupt change in temperature, organisms present in the stream may die or, if able, leave the area that has been affected.
Some things that affect water temperature:
The most obvious is the effect seasons have on water temperature. Streams with groundwater inputs may not change much in temperature throughout the year. Organisms are generally able to adapt to seasonal fluctuations in water temperature, but in some cases oxygen levels are lowered to such an extent that organisms will die.
Stream water temperature might be affected by urban runoff which flowed from parking lots and was heated before entering the stream. Cutting riparian vegetation alongside a stream can decrease shade to the stream, and therefore increase stream water temperature.
Streams or rivers that receive waters that are used for cooling in factories will also have temperature fluctuations. In Wisconsin, these can be more extreme in winter months, as water will be cooler in the river in the winter.
Rivers that are dam controlled may also have temperature fluctuations as waters are held back from flowing downstream of the dam (thus lowering water levels and increasing ability of the sun to heat the water).
data-DissolvedOxygen.pdf (88 K)
Fact Sheet :
FactSeries-Temperature.pdf (897 K)
Temperature Training Video approximate run time 2:27
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