How long does oxygen last in a frozen pond?

This is an answer to a search question that reached the blog.

How long does oxygen last in a frozen pond?

At present we don’t have the information to answer this question reliably because nobody has taken a regular set of measurements of oxygen under ice in a range of different types of ponds – which is what you’d need to do to really work this one out.

But it could last all winter, or the whole time the ice was frozen, depending on whether…

– light can get through the ice (snow cover stops light getting through, and can lead to very low oxygen levels)

– how much biological activity there is in the pond using up oxygen

– are there fish, which could use up quite a bit of oxygen (although less than in summer because in the cold weather they will be less active)

– perhaps most important, how many underwater plants are there, and how many algae, producing oxygen.

If you have submerged plants (maybe stoneworts or mosses which are both winter green), or lots of algae, and light is getting through, and not too many fish, it seems quite likely that the oxygen will last under the ice more of less indefinitely.

In the recent freeze my pond had elevated oxygen concentrations – but its unusual. It has very clear water (because I have been obsessive about keeping nutrients and other pollutants out), and it has underwater plants producing oxygen. These two things are probably not so common.


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