habitat creation | wetland management
Problem plants
These tend to be non native aquatic pests - Water fern (Azolla filiculoides), parrots feather (Myriophyllum aquaticum), and Canadian pondweed (Elodea canadensis), Floating Pennywort (Hydrocotyle ranunculoides). These extremely invasive alien species (some are still sold in garden centres!) can quickly dominate ponds and muddy margins, excluding native plants. There are physical and chemical methods to their removal, either scrape off regularly with a long wooden board (temporary), cover the pond with black polythene, or spray pond surface with glyphosphate herbicide. The last two being very destructive to the rest of the pond, the best way is prevention, know where the sources of your plants have come from so you don't have these problems.
Algal blooms, blanket weed, and duckweed all occur naturally in water of good quality, filamentous algae in particular supports large numbers of small invertebrates. In newly established or excavated pond there may be an algal bloom which is short lived until the pond settles down. However, excessive growth is an a sign that the pond is heavily polluted with nutrients. The combination of this pollution and the thick surface cover of plants can be disastrous for other pond species. The methods for algal and blanket weeds are to scrape off with a rake, do not leave the weed rotting on the bank as the nutrients will leach back into the pond. Fungi present in rotting straw release a toxin that inhibits algal growth, although this superficially treats the symptoms and not the cause, and the long term effect of this method is not known.