Big freeze and ice is 'good for pond life

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.

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.

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.

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 ponds Ponds support more endangered freshwater plants and animals than either rivers or lakes Ponds 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.

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.

So in a pond 50cm deep, it takes over 8 months for oxygen to diffuse to the bottom.

Even under ice, plants continue to photosynthesis, 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.

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.

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.

Under such conditions, oxygen levels can fall significantly.

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.

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.

"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."

World's biodiversity 'crisis' needs action, says UN

The UN has launched the International Year of Biodiversity, warning that the ongoing loss of species around the world is affecting human well-being.

Eight years ago, governments pledged to reduce the rate of biodiversity loss by 2010, but the pledge will not be met.

The expansion of human cities, farming and infrastructure is the main reason.

Speaking at the launch in Berlin, German premier Angela Merkel urged the establishment of a new panel to collate scientific findings on the issue.

Achim Steiner, executive director of the UN Environment Programme (UNEP), urged governments and their leaders to renew their commitment to curbing biodiversity loss even though the 2010 goal will be missed.

"The urgency of the situation demands that as a global community we not only reverse the rate of loss, but that we stop the loss altogether and begin restoring the ecological infrastructure that has been damaged and degraded over the previous century or so," he said.

The UN says that as natural systems such as forests and wetlands disappear, humanity loses the services they currently provide for free.

These include purification of air and water, protection from extreme weather events, and the provision of materials for shelter and fire.

With species extinctions running at about 1,000 times the "natural" or "background" rate, some biologists contend that we are in the middle of the Earth's sixth great extinction - the previous five stemming from natural events such as asteroid impacts.

Cash log

The UN Convention on Biological Diversity (CBD) was agreed at the Rio Earth Summit of 1992, alongside the climate change convention.

But it acquired its key global pledge during the Johannesburg summit of 2002, when governments agreed to achieve a "significant reduction" in the rate of biological diversity loss by 2010.

Conservation organisations acknowledge that despite some regional successes, the target is not going to be met; some analyses suggest that nature loss is accelerating rather than decelerating.

"We are facing an extinction crisis," said Jane Smart, director of the biodiversity conservation group with the International Union for the Conservation of Nature (IUCN).

"The loss of this beautiful and complex natural diversity that underpins all life on the planet is a serious threat to humankind now and in the future."

Mrs Merkel backed the idea of forming a scientific panel to collate and assess research on biodiversity loss, as the Intergovernmental Panel on Climate Change (IPCC) assesses evidence on climatic indicators.

"The question of preserving biological diversity is on the same scale as climate protection," she said.

"It would be sensible to have an interface between the politics and the science to integrate knowledge."

Nature loss 'dwarfs bank crisis'

A large on-going UN-sponsored study into the economics of biodiversity suggests that deforestation alone costs the global economy $2-5 trillion each year.

The UN hopes some kind of legally-binding treaty to curb biodiversity loss can be agreed at the CBD summit, held in Japan in October.

One element is due to be a long-awaited protocol under which the genetic resources of financially-poor but biodiversity-rich nations can be exploited in a way that brings benefits to all.

However, given the lack of appetite for legally-binding environmental agreements that key countries displayed at last month's climate summit in Copenhagen, it is unclear just what kind of deal might materialise on biodiversity.

Political football

The UN has been pursuing new ways of raising public awareness on the issue, including a collaboration with the Cameroon football team taking part in the African Nations Cup finals.

Many environment organisations will be running special programmes and mounting events during the year.

"The big opportunity during the International Year of Biodiversity is for governments to do for biodiversity what they failed to do for climate change in Copenhagen," said Simon Stuart, a senior science advisor to Conservation International and chair of IUCN's Species Survival Commission.

"They have the chance to make a major difference; and key to this will be halting species extinctions, the most irreversible aspect of biodiversity loss."

WWF is highlighting 10 species it considers especially threatened, ranging from commercially significant ones such as bluefin tuna to the Pacific walrus and the monarch butterfly.

In the UK, the national IYB partnership - hosted from the Natural History Museum (NHM) - is asking every citizen to "do one thing for biodiversity" in 2010.