previous page | content page | next page

 

Why are water plants so important?

Waterplants have very important roles in wetlands and waterways, although they are the silent supporters, they help maintain habitat diversity and therefore total species richness.

The other roles water plants play in a wetland system are highlighted below.

Bank stabilisation.

Emergent plants such as the emergent bulrushes, common reed, juncus and floating plants play a very important role in stream and wetland bank stabilisation. Without these deep-rooted plants, much of the mud and soil would be eroded away with high rainfall and turbulent water levels.

Provide food and shelter.

These plants offer sources of food in the form of seeds, root tubers, nectar and plant material. The alga, which grows along the submerged stems, is also a fine source of food for animals such as mayflies and water snails. Water plants may also provide food for terrestrial animals indirectly, as their own food may feed on these plants or live in them.
Provide habitat for Organisms that help to Improve water Quality

Caddis fly larvae use dead leaves and the stems of disused reeds to make their homes. They also feed on detritus.
 
These emergent water plants also provide shelter and habitat for organisms such as water birds, and aquatic animals such as fish, insects and turtles. Submerged plants offer valuable habitat for egg depositing and breeding of many native fish and aquatic invertebrates. The animals that help improve water quality are those that feed on organic matter (detritus) and microscopic particles of algae. By feeding on detritus, they are removing it from the water body.

Help to strip nutrients from water and sediments

Emergent water plants are rooted in sediment and wetland mud, containing many of the polluted sediment particles coming from catchments. Many pollutants from urban areas contain the chemicals phosphate and nitrate. These chemicals are most commonly found in fertilisers, detergents, and sewage (including dogs and other domestic animals) which get washed from gardens, parks, roads and footpaths into urban wetlands. Being rooted in the mud, plants can trap sediments in their roots. This allows the water plants to absorb these nutrients, which they require for growth. By removing these nutrients from the water, they reduce the chance of algal growth in the water body, and thus reduce the chance of alga blooms!

Warbling In The Rushes!

The reed warbler makes its nest in large stands of the Common Reed, Phragmites australis. Feeding on the feather-like seed heads of the reed, and take shelter in the long stems, a pair of nesting reed warblers requires at least 100m of thick Phragmites. Therefore, to offer as many breeding sites as possible for these native birds, the protection or planting of large stands of these reeds needs to be considered.


Australian reed warbler on Bulrush
 
Reduce turbidity by slowing the flow of water, causing suspended matter to settle
 

If incoming water passes through a thick stand of reeds or other water plants, the flow of that water looses its kinetic energy and slows down. As a result, the particles of dirt and pollution are also slowed. Because these particles are heavier than water, the larger particles will fall-out of the water and become trapped in the roots of these plants. The smaller particles, if not trapped in plant roots, will move into the open water and eventually sink to the bottom of the wetland. Slowing the flow of incoming water will also reduce erosion of banks due to the waters energy being dissipated amongst the reeds.
 
previous page | content page | next page
 
Disclaimer & Copyright KESAB 2000
http://www.cwmb.sa.gov.au/kwc/section5/5-11.htm