The surface area of a lake has a significant influence on the amount of mixing the lake will receive from wind exposure. This influences the thermal stratification the water column in that lake which will have a direct effect on the biotic stratification. In turn, the biotic stratification of a lake will affect the overall environmental conditions of that lake, such as pH and chlorophyll content. Lakes with small surface areas sometimes become meromictic with a hypolimnion that never mixes with the rest of the lake. This results in a dead zone at the bottom of the lake in which organismal diversity is very low. In this experiment we compared the thermal and biotic stratification between meromictic Deming lake and a holomictic Lake Itasca within Itasca state park, MN. Deming Lake had a surface area that was much smaller than that of lake Itasca with much less exposure to the wind; therefore, we hypothesized that Deming lake would have a greater degree of thermal and biotic stratification than Lake Itasca which was much more exposed to the wind. We used light meters, pH samples, and conductivity measurements to compare the thermal stratification of these two lakes. We also took water samples to determine the chlorophyll content, and the biotic diversity at different depths to compare the biotic stratification of these two lakes. Our results were consistent with our hypothesis, and showed us that Deming Lake, which was less exposed to the wind, had a fixed thermal and biotic stratification, while the thermal and biotic stratification of Lake Itasca had a higher degree of mixture.
Nelson, Richard; Henry, Justin; Al-Shamisi, Meera; Clifford, Thompson.
The Effects of Wind Exposure on Microorganism Stratification and Distribution in Lake Itasca and Deming Lake.
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