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Introduction How Rivers Run Stories Value Of A River What We Can Do
Quality of a River - Water Quality
Temperature (pg 3 of 5)

Stream life has selected and adapted to the common pattern of temperatures in a stream. It triggers periods of physiological growth or dormancy that define life cycles and rates of maturation.

Many aquatic insects rely on temperature to cue their emergence from juveniles to adults to continue their life cycle. In some species such as turtles, the temperature of developing eggs buried in sand along streambanks determines the sex of the organism. In many fish species, survival itself is temperature dependent.

For example, a small stream in southeastern Minnesota might exhibit all the characteristics of a good trout stream-clear water, riffles, rocky substrate, deep pools with available cover-but if its temperatures routinely exceed about 25°C (77° F), the stream won't support trout year round. Under the warmer temperature regime, smallmouth bass, which are better adapted to higher temperatures would likely be the predominant game fish.

Low temperatures can also stress fish. Below about 7° C (43° F) fish gradually lose their capacity for normal metabolism. In such cold water, some species retreat to slow-moving water where they rest in a state of torpor. But if stream conditions such as a flush of water from a dam force them to seek out new retreats, many may die.


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Introduction
Flow
Shape
Connections
Quality
Description
Temperature
Oxygen
Alkalinity
Nutrients
Sediment
Contaminants
Status
Life
Summary
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