AQUATIC plants imported from overseas and sold for use in gardens and ponds are escaping into the wild, or being dumped there, and are posing a serious threat to biodiversity.

I wrote recently about the unwelcome appearance of an invasive weed called crassula, also known as Australian swamp stonecrop and New Zealand pygmy weed, in our old horse pond.

Now a public awareness campaign has been launched by the Environment Department (Defra) encouraging gardeners to be vigilant in minimising the risks involved in introducing non-native plants, some of which spread into wild areas and wreak havoc with wildlife habitat. Some of the UK’s most precious nature reserves are threatened. Alien pond plants have already spread to the RSPB nature reserves at Old Hall Marshes in Essex and Fen Drayton in Cambridgeshire.

Dr Paul Walton, RSPB lead on non-native species, said: “When people move animals and plants around the world and allow them to escape into areas where they do not naturally occur, serious environmental damage can result. This is one of the main causes of wildlife extinctions. In the UK, aquatic plants have been particularly damaging, spreading from garden ponds and choking wetlands habitats, including many RSPB nature reserves. Once established they are difficult, sometimes impossible, to remove, and a warming climate will make matters worse.

“We need more research into how to manage invasive plant problems. By making people aware of which species present a threat and promoting alternatives for the garden, this campaign is the ideal start. It promises to help protect our wildlife and nature reserves from a major threat.”

The Defra guidance covers four non-native species: New Zealand pygmy weed, parrot’s feather, water fern (also known as fairy fern) and floating pennywort. All of these species have escaped into the wild in Suffolk. Another one found here is Himalyan Balsaam, usually found in riverside habitats. Diane Ling, conservation adviser for the Suffolk Farming and Wildlife Advisory Group, tells me: “The country is full of invasive non-native species. Globally it’s the second highest cause of loss of biodiversity.”

n HUNDREDS of thousands of waterbirds spend the winter in eastern England to escape the harsh conditions in the Arctic and northern Europe. A report published now suggests the number of visitors of some species have increased while others have plummeted. For some declining species, such as the ringed plover and bar-tailed godwit, it seems they are preferring to spend the winter in continental Europe.