Cladoceran
(a zooplankton species) |
Eventually, the lake will start to cool and epilimnion will extend deeper into the water column, eroding stratification. As this happens, the phosphorus that was released to the hypolimnion during stratification (see Figure B) will begin to mix into the epilimnion. While that means that nutrient concentrations will be higher in the surface waters, the algae will be diluted and circulated through the dark bottom water, inducing light limitation. Thus, the lake should clear up a bit.
Winter
The typical northern Missouri lake may be covered with ice throughout the winter. Ice covered lakes stratify, but in a different way. For these lakes the warmer water will be on the bottom. In the absence of ice cover, southern Missouri lakes often mix all winter long.
Thanks to the cold temperatures, some algae and zooplankton species will have died off. Others will have gone into “resting stages,” while a few species will still be active. As the waters warm or conditions become otherwise favorable, the eggs or “resting” cells on the bottom will become active and the cycle will begin again |
