WILDLIFE TRUST WARNS OF ALIEN THREAT TO RIVERS AND PONDS

Wildlife Trust Manager Julian Jones is appealing to people not to buy these plants.

Certain aquatic plants sold by nurseries, pet shops and aquarium centres are invasive aliens. If they escape into the wild they can cause havoc in our rivers and ponds. These plants grow rapidly, blocking out the light and crowding out native species. They kill life on the bottom of ponds and riverbeds and even clog up water treatment works.

Once they are in garden ponds, it is impossible to stop these alien plants spreading into the wider environment. Birds, for example, pick up small fragments on their feet and carry them to other areas. The plants can also spread into the wild when aquariums are cleaned out.

These plants are very hard to eradicate in the wild. They cause millions of pounds worth of damage and can only be controlled by herbicides or by mechanical removal, which is very expensive.

Problem plants still being sold to the public include Australian swamp stonecrop (Crassula helmsii), water fern (Azolla filiculoides), floating pennywort (Hydroctyle ranunculoides), parrot’s feather (Myriophyllum aquaticum), curly waterweed (Lagarosiphon major) and water primrose (Ludwigia grandiflora syn. Jussiaea).

Julian says, ‘The problem is largely due to lack of information. If people knew about the damage that these plants do, they wouldn’t buy them and nurseries wouldn’t stock them.’ He urges the public to be alert and only to buy aquatic plants that are native to Britain. There are many good native oxygenators to use instead of the alien invaders.

For examples, our own white water lily (Nymphaea alba) or yellow water lily (Nuphar lutea) look lovely when in bloom. Or you might grow the yellow flag iris (Iris pseudocarus). In a smaller pond you could use curled pondweed (Potamogeton crispus) or water crowfoot (Ranunculus aquatilis). If you just have an aquarium, then our native water milfoils (Myriophyllum spicatum or Myriophyllum alterniflorum) will do the job of oxygenating the water very efficiently.

The Radnorshire Wildlife Trust’s appeal is part of a national campaign run by Water for Wildlife, a collaboration between several organisations concerned with wetland conservation.

The Wildlife Trusts' website at www.wildlifetrusts.org has more detailed advice, with pictures to help you identify alien pond plants, an information sheet and a poster, all of which can be downloaded for free. Find the A-Z Index on the home page, and then go to ‘Prevent pond pests’.