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Big freeze 'good for pond life' | Big freeze 'good for pond life' |
(about 10 hours later) | |
The big freeze, which has led to many of the UK's ponds freezing over, may benefit animals living beneath the surface. | The big freeze, which has led to many of the UK's ponds freezing over, may benefit animals living beneath the surface. |
Received wisdom says that pond owners should break a hole in the ice to allow oxygen to reach the water. | Received wisdom says that pond owners should break a hole in the ice to allow oxygen to reach the water. |
But new research by conservation charity Pond Conservation has shown the opposite is true. | But new research by conservation charity Pond Conservation has shown the opposite is true. |
Oxygen levels can actually rise in a frozen-over pond, benefiting the animals and plants living beneath. | Oxygen levels can actually rise in a frozen-over pond, benefiting the animals and plants living beneath. |
The recent Arctic conditions and adverse weather has had a significant impact on wildlife, which will be detailed by Snow Watch, a special BBC programme broadcast at GMT2000 on Wednesday 13th January on BBC Two. | The recent Arctic conditions and adverse weather has had a significant impact on wildlife, which will be detailed by Snow Watch, a special BBC programme broadcast at GMT2000 on Wednesday 13th January on BBC Two. |
To safeguard pond wildlife during freezing weather, standard advice has always been to make a hole in the ice to allow oxygen into the pond, says Dr Jeremy Biggs, director of policy and research at Pond Conservation. | To safeguard pond wildlife during freezing weather, standard advice has always been to make a hole in the ice to allow oxygen into the pond, says Dr Jeremy Biggs, director of policy and research at Pond Conservation. |
But new research undertaken by Pond Conservation suggests that most garden ponds and their wildlife will survive during the big freeze if left to their own devices. | But new research undertaken by Pond Conservation suggests that most garden ponds and their wildlife will survive during the big freeze if left to their own devices. |
There are estimated to be around three million garden ponds in the UK, and half a million wild pondsPonds support more endangered freshwater plants and animals than either rivers or lakesPonds provide habitat for a range of species including dragonflies, damselflies, mayflies, water beetles, hibernating frogs and others | There are estimated to be around three million garden ponds in the UK, and half a million wild pondsPonds support more endangered freshwater plants and animals than either rivers or lakesPonds provide habitat for a range of species including dragonflies, damselflies, mayflies, water beetles, hibernating frogs and others |
Ponds freeze from the surface downwards and very rarely freeze completely, leaving large volumes of freshwater under the ice. | Ponds freeze from the surface downwards and very rarely freeze completely, leaving large volumes of freshwater under the ice. |
Making a hole in the ice makes very little difference to the amount of oxygen in this water, says Dr Biggs. | Making a hole in the ice makes very little difference to the amount of oxygen in this water, says Dr Biggs. |
This is because oxygen diffuses so slowly into still water, moving through about 2mm a day. | This is because oxygen diffuses so slowly into still water, moving through about 2mm a day. |
So in a pond 50cm deep, it takes over 8 months for oxygen to diffuse to the bottom. | So in a pond 50cm deep, it takes over 8 months for oxygen to diffuse to the bottom. |
Even under ice, plants continue to photosynthesise, producing oxygen. | |
With a covering of ice the oxygen is trapped in the pond and, if the ice cover lasts for long enough, oxygen levels will rise. | With a covering of ice the oxygen is trapped in the pond and, if the ice cover lasts for long enough, oxygen levels will rise. |
So if garden ponds have lots of underwater plants or algae, oxygen levels can nearly double in the coldest weather. | So if garden ponds have lots of underwater plants or algae, oxygen levels can nearly double in the coldest weather. |
The only time that pond owners should intervene is if they own fish, or the bottom of their ponds are full of silt and dead leaves. | The only time that pond owners should intervene is if they own fish, or the bottom of their ponds are full of silt and dead leaves. |
Then it is worth stirring up the water, mixing oxygenated and deoxygenated water, preferably using a pump or fountain, says Dr Biggs. | Then it is worth stirring up the water, mixing oxygenated and deoxygenated water, preferably using a pump or fountain, says Dr Biggs. |
Also any snow should be brushed from a frozen pond's surface, as it blocks the light and will stop underwater plants from producing oxygen. | Also any snow should be brushed from a frozen pond's surface, as it blocks the light and will stop underwater plants from producing oxygen. |
Under such conditions, oxygen levels can fall significantly. | Under such conditions, oxygen levels can fall significantly. |
Health warning | Health warning |
However, Dr Biggs cautions that pond owners should take great care around frozen ponds, and ensure they never step onto the ice which could easily break. | However, Dr Biggs cautions that pond owners should take great care around frozen ponds, and ensure they never step onto the ice which could easily break. |
According to Pond Conservation, ponds are among the most threatened UK habitats, with government data showing that 80% of ponds in England and Wales are in poor or very poor condition. | According to Pond Conservation, ponds are among the most threatened UK habitats, with government data showing that 80% of ponds in England and Wales are in poor or very poor condition. |
To maintain a healthy garden pond in the long term, says Dr Biggs, make sure that the pond has plenty of underwater plants and is shallow. | To maintain a healthy garden pond in the long term, says Dr Biggs, make sure that the pond has plenty of underwater plants and is shallow. |
"Shallow ponds are better lit than deep dark ponds so can produce more oxygen for their volume," he says. | "Shallow ponds are better lit than deep dark ponds so can produce more oxygen for their volume," he says. |
"Ideally, also keep the pond water as clean and unpolluted as you can to help the submerged plants flourish." | "Ideally, also keep the pond water as clean and unpolluted as you can to help the submerged plants flourish." |
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