Adults and juveniles are much better able to withstand fluctuations in temperature. Furthermore, juvenile and adult fish usually thermoregulate behaviorally by moving to water having temperatures closest to their thermal preference. This provides a thermal environment which approximates the optimal temperature for many physiological functions, including growth. As a consequence, fishes usually are attracted to heated water during the fall, winter and spring. Avoidance will occur in summer as water temperature exceeds the preferred temperature.
Water bodies become shallower when the channels are widened or the volume of water is reduced.
Temperature will increase because a wider channel has more surface area exposed to the sun's rays. The deposition of large quantities of sediment on a lake or river bottom will decrease the channel capacity and force the water to spread out over the banks. A wider channel has more surface area exposed to the sun's rays and temperature will increase. Removal of vegetation allows the sun's rays to shine directly into the water. Temperatures will rapidly rise.