Why do green and brown frogs winter in water bodies?

Brown and green frogs prepare for hibernation when the water temperature is below 10 ° C. They burrow into the bottom silt, where they are all the time of the winter period. Since the entire reservoirs do not freeze, frogs have the opportunity to survive while at the bottom of the reservoir. They breathe with the help of the skin. Oxygen dissolved in water is enough for frogs, since due to lack of nutrition and low ambient temperature, the need for oxygen is reduced.