Ponds are a fantastic ways of attracting wildlife into your garden and create permanent and temporary homes for a wide spectrum of insects and amphibians.
Fast flowing water does not freeze as you can see from this man made stream below only the slower moving edges have frozen. However in extreme weather a powerful pump will be needed to prevent water freezing.
Even when the pond freezes over fully life continues underneath. Many amphibians hibernate in the sludge at the bottom of the pond. Most amphibians are equipped for this temporary freeze. If the weather is harsh and prolonged the freeze can sometimes trap harmful gasses below the ice.
Do not attempt to smash the ice. To create a hole in your frozen pond place a bottle filled with hot water on the ice and it will slowly melt a hole and allow any trapped gasses to release. If this is carried out daily in extreme weather it can be very effective. During short freeze periods your pond life will be normally be fine.