Ponds and streams are often well suited for plant and animal life. On Reykjavik Pond, Tjörnin, there are Mallards (Anas platyrhynchos), other ducks, and Whooper Swans (Cygnus cygnus). In the vicinity of the city, there is Ástjörn a pond with several characteristic aquatic species and further outsite Reykjavik there are many lakes and ponds.
Everywhere in ponds and on
lake banks there are emergent, submerged and floating aquatic plants. Ponds are
often situated in
where you find plant species such as Narrow Smallreed (Calamagrostis stricta),
the tiny Northern bedstraw (Galium boreale), Tea-leaved Willow (Salix
phylicifolia) and the colourful Marsh Violet (Viola palustris).
Commonly by pond banks and shallow ponds, you find the yellow-flowered Marsh Marigold (Caltha palustris), Marsh Cinquifoil (Potentilla palustris), Garden Angelica (Angelica archangelica), and grasses such as Orange Foxtail (Alopecuris aequalis) and Fiorin (Agrostis stolonifera). Robust sedges such as Lyngebye's Sedge (Carex lyngbyei) and Beaked Sedge (Carex rostrata) grow on lake banks, while the thread-formed Arctic Rush (Juncus arcticus) and Common Cottongrass (Eriophorum angustifolium) form large mats or smaller tufts. Tall pond bank vegetation is an excellent place for various ducks and waders to hide.
In lowland marshes and shallow ponds you may find the delicate Whorl-grass (Catabrosa aquatica) and more rarely the large Floating Sweet-grass (Glyceria fluitans). Nesting near the ponds, there are ducks, phalaropes, and grebes. On a quiet early morning you may hear the song of the Common Loon (Gavia immer).
On muddy soils, in wet meadows and shallow ponds in South Iceland you will see the occasional Water Speedwell (Veronica anagallis-aquatica), while the puny, white-flowered Starwort Mouse-ear (Cerastium cerastoides) and Common Spike-rush (Eleocharis palustris) grow on pond banks.
The true aquatic plants, the pondweeds (Potamogeton) and bur-reeds (Sparganium), are found deeper in the pond. Pondweeds often have leaves floating in the surface, while the plants remain attached on their long stem. Submerged water-milfoils (Myriophyllum) are found even further out in the pond water. In the water surface, there are free-floating species such as the Lesser Bladderwort (Utricularia minor), a mysterious insect–eating plant, and swarms of tiny algae and bluegreen bacteria.