What is the role of anomalous behaviour of water in preserving aquatic life in regions of cold climate?

Explanation

In cold regions, during winter , the temperature of the atmosphere fall well below ` 0^(@)C` . As the temperaute decreases, the water at eh surfaces of lakes and ponds starts contracting . Hence, its density increases an d it sinks to the bottom. This process continues till the temperature of all the water in a lake falls to` 4^(@)C` . As the water at the surface cools further i.e, its temperture fall below ` 4^(@)C` it starts it remains at the surface. i.e, its temperature of the water at the surface is continues to fall to` 0^(@)C` . Finally , the water at the surface is converted into ice, but the water below the layer if ice is at `4^(@)C` . Ice is a bad conductor of heat, Hence, the layer of the ice at the surface does not allow tranfer of heat from heat from the water to the atmospher. As the water below the layer of ice remains at ` 4^(@)C` , fish and other aquatic animals and plants can survive in it .