The bathythermograph records a temperature profile of the water column. On the day of a cruise, one can get an indication of the surface water temperature on Lake Michigan by querying the Michigan Sea Grant Coastwatch site. An example of the surface temperature data is found in Figure 7, which is based on information from the Coast Watch Internet Site. Several interesting studies can be made of the data obtained from temperature readings. Most prominent is the identification of temperature stratification at various depths and the relationship to the seasons of the year.
Stratification refers to distinct layers of water that form in the lake.
The stratification, or lack of it, is associated with vertical motion of water in a lake. The temperature readings also give an indication of whether conditions are favorable for cold water fishes. The rate of metabolism of cold-blooded animals as well as rates of photosynthesis are temperature sensitive. The migration of fish and spawning behavior are associated with temperature changes. Temperature and dissolved oxygen are related as warmer water holds less oxygen than cooler water.