As water temperatures increase, the density decreases. During the spring, stratification will break down allowing mixing of oxygen and nutrients. Eventually, the surface water layer falls below 4 degrees C, becomes less dense, and remains at the surface. EPA has developed an equation to determine maximum weekly average temperatures for growth and survival of fish species. Please click on the following fish groups for which you wish to examine more detailed temperature preferences.
Temperature can exert great control over aquatic communities.
If the overall water body temperature of a system is altered, an aquatic community shift can be expected. Also, different plankton groups will flourish under different temperatures. In addition, there is potential for physiological distress if a fish swims into a localized warm area of the water. Because of water's high heat capacity, water temperatures do not change rapidly under natural conditions. Thus, fish have not evolved the ability to adapt to rapid temperature fluctuations.