Because of the warmer waters and more plentiful food supply, almost all creatures spend the summer months in the upper layer. During spring and fall water flows all over the lake, and the temperature is more uniform. Fish and other animals are found all over the lake. Even in cold climates, most lakes are large enough so that they don't freeze solid, unlike ponds. During the winter months some creatures hibernate in the bottom mud.
Some fish continue to feed, but less actively.
A layer of ice can develop on the top of lakes during winter. The ice blocks out sunlight and can prevent photosynthesis. Without photosynthesis, oxygen levels drop and some plants and animals may die. The Evergreen Project, Inc.