Water – life, transport, power
Freshwater systems are essential to tropical life. River systems provide long thin, but continuous, habitats with high connectivity along which species spread, and rivers also provide routes of navigation through forests for humans. Ponds and lakes are less connected and this can sometimes lead to a great deal of speciation as seen in the Cichlid fish of East Africa. Tropical freshwater is a complex series of differing and sometimes contrasting environments from the acidic brown streams of the Amazon basin to the calcium rich rivers in parts of Africa.
The flora and fauna of these systems is equally diverse. In fast flowing streams grow Podostemaceae, strange plants that glue themselves to rocks and have athallus like growth, in slow water the giant Amazon waterlily (Victoria amazonica), with leaves over 3m in diamter, but also tiny floating plants from the Araceae, watermeal (Wolffia spp.) where a whole plant is only 1mm across. Water plants very often reproduce by fragmentation and will then re-root and grow new colonies leading species such as Water Hyacinth (Eicchornia crassipes) and water fern, (Salvinia spp.) to be problem invasive weeds.
On the margins of the water and in river deltas the nutrient rich sediment allows spectacular plants such as Papyrus (Cyperus papyrus) to flourish.
These aquatic systems can have a high productivity, both the plants and the fish providing food for man.
- Salvinia molesta (Kariba weed) originated in Brazil but clogged the world’s largest artificial lake (Kariba) in Africa
- Water Hyacinth (Eicchornia crassipes) can double in size every two weeks
- Victoria amazonica (Giant waterlily) flowers are pollinated by scarab beetles
- The smallest flowering plant is Wolffia, a floating member of the Araceae
The tropical biodiversity greenhouse pond has a volume of around 2500litres and varies from about 80-110cm in depth. The temperature is maintained using three 500w thermostatic heaters set at 22C. It is filled with rainwater collected from the glasshouse roof.
Planted are Cyperus papyrus, Nymphaea ‘King of Siam’, Cabomba caroliniana, and floating are Eicchornia crassipes, Pistia stratiotes, Salvinia herzogii, and Utricularia gibba. The pond also has some ramshorn snails and pond snails that made their way in on the water plants and a vibrant population of zebra danios which swim just under the surface giving the pond a lively appearance.
See our pond being built on the blogs pages.