The individuals who have fallen through the ice and been submerged under cold water for long periods can sometimes be revived - explain.

Explanation

Temperature variations occur with seasonal changes. These differences in the temperature form thermal layers in water. Water shows maximum density at` 4^(@)C` decrease its density. Generally the winter season the surface water cools down the upper water phases in the temperature reaches `0^(@)C.` below the upper icy layer the cool water occupy the lake. The aquatic animals continue their life below the icy layer at lower temperature the activity of bacteria the rate of oxygen consumption by aquatic animals decrease. Hence organisms can survive below the frozen (icy) upper water without being subject hypoxia.