Many plants and animals survive surface freezing of freshwater lakes, in dormant life stages, by reducing activity beneath the ice, or by moving. Such freshwater lakes vary enormously in size and distribution, providing a wide range of habitats for many organisms, which undergo a succession of emergence during lake thaw. The annual thaw triggers highly productive plant and animal activity, beginning with diatom algae and then zooplankton. Habitat diversity increases with lake size, increasing the variety of plankton, aquatic plants, waterbugs, birds, and sometimes fish.