Invasive plants are taking root in the Isle of Man's water courses, the government has warned.
The Department of Agriculture, Fisheries and Forestry (DAFF) said the non-native aquatic plants could be difficult to spot and hard to control.
The plants, including New Zealand Pygmy Weed, take oxygen from the water and threatened wildlife.
The DAFF is asking pond owners not to move "spare" weed from garden ponds to ponds, streams or quarries in the wild.
It said it was an offence under the Wildlife Act 1990 and had already resulted in invasive species appearing in places such as Scarlett quarry and ditches beside the Heritage Trail, the DAFF said.
The other non-native plants causing concern include Water Fern Azolla filliculoides, Parrots Feather Myriophyllum aquaticum and Floating Pennywort Hydrocotyle ranunculoides.
The New Zealand Pigmy Weed was first brought into Britain in 1911 from Tasmania, and is now sold as an "oxygenating" plant in garden centres across the UK. It has been on the island since the 1990s.
The plant can spread rapidly and forms very dense mats threatening native species of aquatic plants and wildlife, especially our frogs.
Phil Gawne, Minister for Agriculture, Fisheries and Forestry, said: "The public can play their part in preventing the spread of invasive species in the island by ensuring that they do not buy known invasive aquatic species from garden centres and by responsible disposal of garden waste that may contain potentially invasive species."