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WORLD ENVIRONMENT DAY |
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We are commemorating World
Environment Day on 5 June 2011 with
a beach walk in the Coastal section
between Dolphin Beach and Sunset
Beach. |
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Join us for the walk and contribute
to World Environment Day by helping
to clean up litter along the way. |
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Meet at the Dolphin Beach Parking
Area (next to the hotel) at 14h30 on
Sunday, 5 June 2011. |
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EVERYBODY WELCOME – BRING A BLACK
BAG FOR THE LITTER. |
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PLEASE CONTACT Pauline on 083 255
2537 if you require further
information. |
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EVENTS |
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On Sunday afternoon 17 July we
will be having an Indigenous
Garden work party. Our
indigenous garden at the
entrance to Rietvlei is being
revamped, as was reported in our
previous newsletter, but we need
to get some hands in there to
help with some weeding and
clearing in general. More
details about this later. |
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WESSA FRIENDS GROUPS MEETING AT
RIETVLEI |
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The WESSA Friends Groups meeting
on Saturday 14 May was attended
by about 25 people, representing
various Friends groups and WESSA
staff members. We started off
the programme with a short
presentation on various
challenges Friends of Rietvlei
has and how we are dealing with
these. Then representatives of
several of the Friends groups,
inter alia Zoarvlei, Bracken,
Liesbeeck River and Tokai
Forest, reported back on their
activities and some of the
problems they have. |
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Tony Rebelo from Friends of
Tokai Forest gave a presentation
on the introduction of iSPOT, a
web-based system of recording
sightings of plants and animals.
This is developing rapidly in
the UK, and a South African
section is also being tested; if
all goes well the system will be
fully implemented towards the
end of the year. |
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After a light lunch, many of the
participants joined us for a
walk to the two bird hides. The
water levels were very low and
because of this, the bird hides
were not really the most
suitable places to view birds;
but on the way to the bird hides
there were a large number of
birds on the central pan. A
large flock of flamingos decided
to give us a fly-past show and
thrilled us with their display,
wheeling and turning right over
where we were standing at the
time. |
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Thanks to all our members who
assisted to make this a
memorable day. |
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The Estuarine Tube Worm |
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At our AGM a member of the Milnerton Canoe Club
raised the issue of the problems caused by tube
worms in the lower estuary, particularly in the
vicinity of the two bridges at Woodbridge Island. We
did some background reading to find out more about
this little pest. |
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The Estuarine Tube Worm or Australian Tube Worm,
Ficopomatus enigmaticus, comes from Australia and
was first noticed in South Africa in the Cape Town
area in 1951; probably introduced on the hulls of
ships. It now occurs in estuaries in the Cape
Peninsula and along the south coast. The tube worm
has spread to many countries and most often causes
problems by blocking intake and discharge pipes of
power plants and also interferes with the operation
of locks. |
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Ficopomatus enigmaticus is a small polychaete which
builds and lives in a white calcareous tube about
2mm in diameter and 2 cm long. The worm feeds by
extruding 12-20 branching gill plumes out of the
open end of the tube filtering small food particles
and passing them down to the mouth at the base of
the plumes. At the same time blood passing through
the gill plumes is oxygenated. When disturbed the
plumes are withdrawn into the tube and the entrance
sealed with a tough spiny operculum at the end of a
modified gill plume. |
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The estuarine tube worm lives mostly in shallow
water on rocks, concrete, wood, shells and other
hard surfaces. It can occur as single, separate
tubes, or as tangled, agglomerate masses forming
incrustaceans up to 10cm or more thick. It does
survive in sea water, but can only grow and
reproduce in lower salinities of about 10-30 ppt
(sea water is 35ppt or parts per thousand), and in
water temperatures above 18ºC. Eggs and sperm are
released into the water and the larvae live in the
plankton, settling on a hard surface to start
building a tube after 20-25 days. |
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The ecological effects of the tube worm in an
estuary has not been studied in detail, however it
does remove suspended particulate matter, reduces
excess nutrients and improve oxygen levels in waters
with poor water quality, particularly enclosed
waters like boat basins and docks. Very high
populations could compete for available food sources
with other filter feeders. |
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In the Milnerton Lagoon the presence of Ficopomatus enigmaticus is mainly a nuisance where it grows
under the wooden bridge and the road bridge. At the
wooden bridge the colonies on the stones under the
bridge is obstructing the free passage of canoes,
particularly when the water levels are low.
Fortunately it is quite easy to control – colonies
can be removed mechanically or by hand; but
recolonisation occurs quickly because of the highly
mobile larvae and rapid growth rate. |
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The ultimate solution in this estuary would be to
return the estuary to its natural state with a
natural salinity regime – while this may not
completely destroy the colonies, it will certainly
slow down their growth and reproduction so that they
will decrease to more manageable levels. This is of
course a major objective of the Diep Estuary
Management Plan, and the implementation of the plan
is imperative to resolve issues like this
infestation of Ficopomatus enigmaticus. |
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MY FIRST MyCITI BUS TRIP |
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On Thursday 19 May Niel van Wyk took to the pink
road for a trip to town. Here he relates his
experience: |
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I have to go into the City Centre at least once a
week on business, and on Thursday 19 May decided
that I must use the new BRT system. I live in Royal
Ascot, just more than 1 km from the Racecourse Bus
Station, and about 14km from the City Centre. |
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It was a lovely sunny morning so I decided to walk
to the station, arriving there at about 10h30.
Having bought my ticket, the MyCiti bus arrived
shortly afterwards and I boarded it for the drive to
the City. There were about 20 people on the bus
already, and at all the stations between Racecourse
and Lagoon Beach people were disembarking and/or
getting on. However after that, right through
Paarden Island and Woodstock, no more passengers
either got on or off the bus. |
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We arrived at the Civic Centre station about 20
minutes after leaving Racecourse, and I transferred
to the Gardens intercity service as I wanted to be
up in Loop Street in the vicinity of the Vlaeberg
Post Office. The wait at the station for the Gardens
bus was about 25 minutes, slightly longer than the
scheduled 20 minute interval in the service (between
09h00 and 15h30 there should be a bus every 20
minutes). Eventually the bus arrived and I travelled
up Long Street without having to worry about whether
I would find parking. I disembarked at the Dorp
Street stop and walked up to Loop Street; and,
having concluded my business caught the bus in Loop
Street back to the Civic Centre where I transferred
to the Table View bus. |
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At the Racecourse and Civic Centre stations there
were plenty of very friendly and helpful staff who
really went out of their way to assist the
passengers; advising which way to go, what to do,
etc. When I paused to look at the mural on the wall
in the Civic Centre station, a friendly voice
immediately asked whether I needed assistance and
where I wanted to go. |
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The trip back was quick, and I was back home just
before 12h30. The whole trip thus took me nearly two
hours, but keep in mind that I walked to the station
and back, that is about 25 minutes in total. If I
had taken my car into town, the round trip would
probably have taken me about 50 minutes, so the bus
experience was about 45 minutes longer. |
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Comparing the costs of the bus to travelling by car
proves that it does pay to take the bus. My car runs
on diesel, and with the help of the AA vehicle
operating cost formulae, I worked out that the fuel
alone for a trip straight there and back (no driving
around in town) is about R26.39 at current fuel
prices. However, using the formula for determining
total vehicle operating costs, a trip to town and
back in my car costs R42.00, more than 1½ times the
R20.00 cost of a return ticket to the City Centre.
Just to break even on the fuel, the price of diesel
will have to drop to below R7.80 per litre, a price
I don’t think we’ll see soon, even then the total
vehicle cost for the trip will be R35.56. |
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Taking the MyCiti bus on the pink road to the City
Centre does pay, and you do not have the hassles of
coping with irresponsible drivers or the problem of
finding convenient parking in town. You may have to
walk a bit to get to your destination, but that can
only be good for your health. The service is good,
apart from a few teething problems in the inner City
routes, but in time this will improve and we will
have a really great public transport service. |
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I can certainly recommend the MyCiti bus service to
people living in our area; I know that I’ll be using
it regularly. |
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CONTACT NUMBERS AT THE RESERVE:
Environmental Education Centre – 021 521 9900
Entrance Gate – 021 557 5900
Emergencies and standby number 071 268 9637 |
