Frozen water (ice) has less density than liquid water. How does this property of water affect life on earth?

If frozen water were less dense than liquid water then it would sink, rather than float. The biggest impact of this would of course be in bodies of water where the frozen ice would rest at the bottom of lakes, rivers, etc. rather than floating on the top. This would be devastating to the life in these bodies of water who would not be able to survive in these conditions. There is also the fact that if ice sunk to the bottom, it would take longer to thaw completely, meaning that much of the water sources found in climates that experience a period of coldness would never thaw completely. It would be devastating to the existing ecosystems.