Friends of Rietvlei
Newsletter February 2008
As the first newsletter for this year, the Committee would like to wish all members and friends all the very best for 2008. We hope that this will be an environmentally aware year for you and that you will make an effort to support the conservation efforts at Rietvlei in every way.
Our first Activity for 2008 was a walk to the bird hide on Sunday 3 February to coincide with World Wetlands Day. Niel van Wyk reports as follows:
Saturday 2nd February was World Wetlands Day, to commemorate this day we had a walk to the Bird Hide on Sunday 3rd February. February is Wetlands Month. The Ramsar theme for Wetlands this year is "Healthy Wetlands, Healthy People" - this basically means that having healthy well-functioning wetlands can only enhance the health of people the world over. Wetlands cleanse water and improve its quality, they prevent flooding, and they can counter the effects of droughts. Wetlands also support a large variety of living organisms and are important in many aquatic and terrestrial food chains. As such wetlands are important sources of food for local communities in many parts of the world, either directly in the form of fish, or indirectly where crops are planted and grown on the floodplains during dry seasons - these floodplains are allowed to flood during the wet seasons during which time the soil is enriched by nutrients.
There were about 10 people on the walk to the Bird Hide at Rietvlei. The strong south-easters of the previous days (or weeks!) had died down and the weather was really pleasant for walking. When we started off it looked as if it could rain, but this soon cleared up. Of special mention is the sighting of two fish-eagles that kept us company for most of the afternoon.
As usual, Niel has posted the photographs taken on the walk on the website. They are stunning photographs and you are encouraged to take a look, whether you were there on the walk or not.
Our first Evening Talk will be held on Thursday 6 March. Our speaker will be Pat Holmes and she will be speaking on “Riparian Restoration” of fynbos. This interesting talk and power-point presentation on restoring the natural vegetation along river courses is of interest to us as we have our fair share of alien vegetation along our river and vlei.
Please join us at the Rietvlei Education Centre, Table View, at 7:30 for 8:00pm
Queries? Phone Pauline on 083 255 2537
Annual General Meeting: An early notification of our AGM - it is going to be held on THURSDAY 8 MAY 2008, in our Education Centre. More details nearer the time.
The school year has begun and we are hoping to be playing host to a greater number of schools on environmental outings. Elana Kellerman was a conservation student at Rietvlei in 2007 and she has been appointed by the City of Cape Town as an intern for a year to do environmental education. We are hoping that she will spend a substantial amount of time at Rietvlei. She will possibly be occupying the office in the Education Centre if a telephone line can be installed there. In the meantime she can be contacted via the gate number, 021 557 5509, if you know of any group wanting to visit Rietvlei.
Potamogeton in Rietvlei
A problem to the recreational users of Rietvlei is the excessive growth of Potamogeton pectinatus, the water grass also known as sago pondweed, or fennel-leaved pondweed. It has always been present in Rietvlei, but the last few years have seen a bloom in growth.
There are about 20 Potamogeton species, most of which occur only in the northern hemisphere; Potamogeton pectinatus is the only one found throughout the world. It grows in wetlands, lakes, rivers, canals, ditches and ponds from sea level up to nearly 5 000m above sea level; it is also the only Potamogeton species found in brackish water. It has been recorded growing in waters 6-7m deep, but it is dependent on light penetration and in turbid waters will rarely grow in waters deeper than 3m.
Potamogeton stands are important feeding and rearing habitats for waterfowl, fish and many other organisms. It is not only a source of food, but also provides a protected habitat for many aquatic animals. In many parts of the world migratory waterfowl have established their migration pathways via water bodies dominated by Potamogeton spp. Potamogeton also protects shorelines from erosion as they serve as a very effective buffer against wave action. Potamogeton plays an important role in keeping water clear.
However, there is also a downside to Potamogeton. Because it grows so prolifically, it can clog irrigation canals and is a nuisance to recreational users – it interferes with fishing lines and winds around powerboat propellers.
A lot of research into control methods has been carried out throughout the world, including the use of herbicides and other chemicals, mechanical methods and biological control. A burrowing chrysomelid beetle causes great damage to Potamogeton, but has not permanently eradicated the plant in study areas. Grass carp was introduced into the United States to control aquatic plants, but it has exterminated virtually all aquatic plants in water bodies to which it had been introduced and caused a complete collapse of the ecosystem – leading to the disappearance of other fish and bird life in such systems.
The problem recreational users, such as the boaters and fishermen, have with Potamogeton in Rietvlei will not be easily solved. In fact people using Rietvlei will have to accept that the plant is here to stay and learn to live with it. The only remedy is to clear channels in the Potamogeton stands to allow boats access to the shore, it can also be cleared in areas where anglers require access to the water. However such clearing will have to be repeated at regular intervals to ensure that channels stay open.
RAIN in February (not to mention the WIND)
The wind seems to have been unrelenting so far this year. It is known as The Cape Doctor, but judging by the number of people who complain of allergies, hay-fever and sinus problems when the wind is blowing, this could be a misnomer! But … there have been some days of rain. At this time of the year many people are worried about the Central Pan drying out and that heavy winds will lift the fine silt and blow it over Flamingo Vlei. The City of Cape Town has instituted measures that were agreed to at the start of the financial year in July 2007. In January two diesel pumps were installed in a temporary shed on the southern edge of North Vlei. The pumps are pumping water on a daily basis onto the central pan. The good rains of early summer also helped to keep the pan wet. Unfortunately the heavy southeasters and high temperatures have done there bit to accelerate evaporation. At present the pan seems to be wet enough.
The City’s Roads and Stormwater Dept has appointed consultants to plan the upgrading of the stormwater channel that runs past Bayside Shopping Centre and Pick’nPay and enters Rietvlei just south of the soccer fields. Capacity for stormwater and water quality, are issues that will be investigated. There will be a public participation phase to the project.
The new Integrated Zoning Scheme (IZS) for the entire City is out for public comment. Niel Van Wyk investigated the maps and zoning for Rietvlei and picked up some discrepancies and concerns. These will be submitted to the Planners.
Spatial Development Frameworks (SDF) for the 8 Planning Districts of the City are being prepared. The SDF for Blaauwberg will be available for comment soon. The questions being asked are:
  How do you see the future of the City?
  Do you think Cape Town should spread out as far as possible? Or that new buildings should be at least three stories high, to help prevent urban sprawl?
  Do you think it's worth preserving endangered fynbos rather than building houses on it? And if so, where should new houses be built instead?
  And how are we going to connect Capetonians with each other, and with economic opportunities? Through better public, or private, transport?
The Committee will be actively involved in the above matters and will submit comment where necessary…. So can you!!
Thanks go to Chevron Refinery for sponsoring envelopes for the posted newsletter.
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