Friends of Rietvlei
Member of the Wildlife & Environment Society of South Africa Western Cape Region
Newsletter May 2010
The new financial year has commenced and all Ordinary and Family members must pay the subscription for 2010/11. Please renew your membership as soon as possible.
Friends of Rietvlei AGM
Thursday 13 May 2010 at the Rietvlei Education Centre at 7.30 for 8.00pm.
After the formal business, which will be as brief as possible, there will be a talk entitled:
Niel van Wyk will give an illustrated talk on the fish species found in Rietvlei and the estuary.
Refreshments available. Queries or apologies – phone Pauline on 083 255 2537
Join us for an interesting walk on Blaauwberg Hill, exploring some of the area’s unique biodiversity.
Date: 15 May 2010
Meeting place / time: Eerstesteen Resort at 09:30
Entrance fee: R20 per walker for non-Friends participants
To bring: Picnic, water, hat and hiking boots
Hiking distance: Approximately 3kms and Duration (including picnic): 3 – 3.5 hours
Bookings are essential (max. 30 walkers)
Contact the Blaauwberg Conservation Area on the 021 554 0957 or e-mail us on
This all important work of removing alien vegetation must continue year in and year out and we call on all members to lend a hand!
Date: Saturday 22 May Time: 08h00 to 10h30 Meet: at the gate to the Model Aircraft field on the R27.
For all queries please contact Nelis VIsagie on 082 777 5708.
In our previous newsletter we listed the various projects that have been initiated. There are already some interesting preliminary results coming out of some of the short-term investigations and we will report on this as soon as these projects have been finalised. An official request has been submitted to the City for funds for implementing the very important hydrology and geohydrology project – this project is to study the dynamics of water flow and sediments in the system and is vital to provide us with an understanding of how the system works.
Christopher Singo is the new Site Officer, appointed by the City of Cape Town, for the Diep River/Fynbos corridor area. He and Henk Louw are working together to manage this important area. Christopher was previously a conservator at Table Mountain National Park. Christopher is a valuable addition to the conservation staff in the area, and we welcome and support him in this important work. We have also supplied Henk Louw with a pair of binoculars and a camera for his field work. Quick observations, and the recording of them, are essential for both law enforcement and recording species and events.
New People In and Around Rietvlei
Rifqah Johnson started as Environmental Education intern at Rietvlei in March and has already been very active in getting groups of learners to attend courses at the Educational Centre.
Proposals for development of the Gold Circle stable properties at Milnerton Racecourse.
In our February newsletter we reported about our concerns with shortcomings in the Draft Basic Assessment Report for the proposed mixed-use development at the Gold Circle Stables on Koeberg Road. Since then a formal application for the rezoning has been submitted to the City, even though the Final Basic Assessment report has not yet been submitted to Province.
We objected to this rezoning application on the grounds that the application was premature, and also that the existing layout was not acceptable. Our concerns with the draft report was the basis for our objection and were added to our submission to the City.
Expansion and Upgrading of Wastewater Treatment Infrastructure in the Blaauwberg Area.
There have been various behind-the-scenes developments taking place with respect to the proposals for this expansion and upgrading. At this stage we are not in a position to report on the situation, but you can be assured that your committee is keeping a close eye on these developments to ensure that our interests, and those of Rietvlei and the environment, are given due consideration.
Light Pollution at Rietvlei
We were horrified to see the row of lamp poles being erected along the R27 on the western boundary side of Rietvlei. The visual impact is severe between Sunset Beach and Dolphin Beach, particularly on that side where the horizon is low and there are no high buildings or other developments to spoil the view. Although there is continuous traffic along the R27, this traffic is on a low level and is not so obtrusive.
However, apart from the visual pollution caused by this row of lights, we are very concerned about the effect on the environment of this high level lighting. We discovered that in the original environmental impact study for the IRT, the possible effects of light pollution had not been included in the report. This is in spite of the fact that there is a considerable amount of published literature available on light pollution.
Light pollution has negative effects on plant and animal physiology – it confuses animal navigation, alters competitive interactions, changes predator-prey relations, and can cause physiological harm. The rhythm of life is orchestrated by the natural diurnal patterns of light and dark, disruption of this pattern impacts on ecological dynamics. The effect of light pollution on natural ecosystems was first studied in 1938, but it is only in the last 10 years that substantial research in this field has been undertaken. A wide range of consequences of light pollution has emerged in this research.
A few examples that may apply to Rietvlei are briefly related here, but keep in mind that the high level lighting along the R27 could have more effects.
It has been shown that lights around lakes and wetlands prevent zooplankton from rising to the surface and feeding on surface algae at night. This can contribute to algal blooms which lowers water quality. Artificial light at night also interferes with the ability of moths and other nocturnal insects to navigate, which in turn could negatively affect night-flowering plants dependent on moths for pollination. Lights at night can also interfere with the breeding activities and reproductive cycles of frogs and toads – in many species these cycles are cued by moonlight and constant artificial light confuses the animals.
Migrating birds are often disrupted by high level artificial lighting – in some parts of Canada there is a programme whereby lights on tall structures are turned off during bird migration periods. In the North Sea researchers are experimenting with new lighting technologies to reduce the effect of offshore oil and gas platforms on the migration routes of birds. Some birds fly around only at night and could be discouraged from such flights by excessive night lighting, a local example is the African coot who fly in considerable numbers between water bodies at night – we don’t know what the effect of more night lighting would be on birds like these in Rietvlei.
Studies have also shown that night lighting can have severe effects on insectivorous birds feeding at dawn and dusk as the insects they feed on are attracted to artificial lights whereas the feeding birds mostly avoid lights. The same applies to bats feeding at night as they also tend to avoid lights while their prey is attracted to lights. Further, large numbers of these prey species die at these lights each night, this leads to a decline in the prey population which also negatively affects the populations of insectivorous birds and bats.
These few examples illustrate that night lighting can have far-reaching effects on the natural environment. We do not know what the effects of the newly erected high level lighting on the R27 will be on Rietvlei, but from research done elsewhere in the world we do know that it is most likely negative. The lighting on Otto du Plessis Drive along the estuary in Milnerton has very likely impacted negatively on the animal life in and along the estuary over the years – but we will probably never know exactly what or how big this impact has been.
The Friends of Rietvlei submitted a brief report to the City on this important issue. We proposed that even at this late stage it is necessary to investigate in more detail the effects of this lighting on Rietvlei, and also to consider ways and means by which negative effects can be mitigated. We realize that they may not remove the lights, but steps such as switching the lights off for a period at night when the buses are not operating should be considered.
Energy Efficiency or Energy Reduction
Energy efficiency has been described as a renewable energy resource that is perfectly cheap, abundant and immediately available. It can reduce carbon emissions and reduce our dependence on imported energy resources. It does not pollute, and it does not depend on the weather like solar and wind power. There are several ways of improving energy efficiency in your home – here is another tip:
You can save both water and electricity by reducing the amount of hot water you use in your kitchen sink or bathroom basin. This can easily be accomplished by using a small round plastic basin inside your sink and washbasin – there are various size basins that fit inside the sink or washbasin very nicely. With such a basin you can reduce the amount of water required by up to 50%.
Thanks go to Chevron Refinery for sponsoring envelopes for the posted newsletter.
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