In the comments Richard asks:
Richard: Are your ponds covered in snow; ours has been over the past few days?
Jeremy: Yes – both ponds have been covered by about 15 cm snow since Tuesday night (the 5th Jan).
Richard: I’ve only just got round to clearing it? Would that affect photosynthesis of the plants underneath.
Jeremy: If the snow cut out all the light then whilst there was snow cover there wouldn’t be any photosynthesis. Once you’d cleared the snow I would expect plants to start photosynthesising again. However, when it comes to photosythesis my knowledge is at a pretty basic observational level: I know it happens in the sun, and not in the light, and you can see a dissolved oxygen response!
Richard: We also broke the ice – to give the birds something to drink and it’s 5cm thick, in fact the pondweed is frozen inside it. Do you think this would be a fatal blow to the snails and plants inside, or will they recover?
Jeremy: I think the plants frozen in the ice will probably recover and snails probably not. As far as I know the water snails you find in Britain are not resistant to freezing, but I wouldn’t be completely surprised if there were a few exceptions.
There is an American frog that does survive actual freezing, although our Common Frog does not. See the earlier post ‘Really, truly, actually frozen frogs‘.
