Replanting the Pond
at the Department of Botany,
University of Pretoria, South Africa

By Jacques Gerber - Click images to enlarge

When I came to the University of Pretoria in 2001, I discovered that the departmental pond was in a shocking state. Water level fluctuated, and the waterlilies (all non-indigenous hardies) were planted at a depth of 10cm. The fish population consisted of 10 or so large Cyprinids (some goldfish, carp and a single koi). I managed to convince the garden committee that the pond was in serious need of a replant. Finally in September 2002, the project went ahead. The pond was pumped dry and the large fish caught.

Turned out there was also a sizeable population of Southern Mouth Brooders in the pond, and these pictures show myself and Andre Grobler, a colleague of mine in the Plant Ecology Unit, trying to rescue as many of these as possible. We managed to rescue over 200, and for the next three weeks they made a complete mess of my aquaria.

The pond was built some time during the 1950's. The bottom is concrete, and the sidewalls are brick. At some point it was painted blue like a swimming pool. Plants were in pots, scattered around the pond on pillars. Roots from surrounding trees had broken through the brick wall in places, and two cycads that were planted to close to the pond had actually cracked the shell. In some places the sludge in the dam was two feet thick. We moved the worst offender of the two cycads, a large Encephalartos transvenosis, chopped out and filled the cracks, and built planting platforms in places around the pond sides. This is far from the best way to do it, but funds were short - very short. All the plants, with the exception of a Sauraurus cernua, were repotted, and just as well. None of them were planted in soil, only aquarium gravel! This was remedied.

Only one of the old waterlilies was retained, and this turned out to be a magenta flowered hardy. It's interesting that the main nurseries in South Africa that stock aquatics are in areas that are generally too cold for tropicals. It's warm enough here in Pretoria, but the nurseries here don't even have N. capensis, only hardies. Our latitude is approximately that of south Florida.

We managed to purchase three Nymphaea capensis (Cape Blue Waterlilies), several Aponogeton distachys (Water Hawthorn or Waterblommetjie) and a Nymphoides indica (Pond Fringe). Marginal plants include Cyperus papyrus var. nana, Persicaria lapathifolia, Persicaria amphibia, Ranuculus mutifidus, and Cyperus immensis.

 The pond was then refilled and turned out to leak like a sieve. The pictures at the left show myself and Peter Shabangu, one of the garden staff, building a leak containment wall across the stream leading to the waterfall. Although the pond is meant to be Peter's responsibility, he now refuses to maintain it, so I do instead, not that I get paid...The wall worked, and the pond now only loses 2.5 kilolitres per day instead of 7 kilolitres. This is really still too much, but it has to do for now. We figure the trees are using the water.

The rest of the pictures, below, show myself and my student Retief Grobler (no relation to Andre) planting plants I collected at Rust de Winter Dam, including the Nymphaea caerulea. Other plants put in that day were Typha capensis, and Najas horridus, as well as several members of the Scrophulaceae, a Potamogeton species,and a Schoenoplectus species. Kit Knotts has provided us with a

  number of night blooming tropical cultivars which arrived the morning I wrote this. In case you're wondering why I'm wearing a diving mask - I wanted to count the number of flower buds on the waterlilies, and the water is a bit murky from above.  


Right now the waterlilies are doing well, as are most of the other plants. The night bloomers have been planted, and I hope for good things from them. Plans for 2003 are hopefully to empty the pond again, replaster and waterproof the shell properly, build planting ledges in the pond from rubble and concrete, and then waterproof these as well. This should make the pond reasonably waterproof, and provide a double layer of protection. The planting ledges will permit planting directly into soil instead of in pots. Plans include a large shallow area for Nelumbo nucifera (Lotuses), and a bog garden for delights such as Gunnera perpensa, Ranunculus multifidus, and other wetland plants that don't like being under water. The deep part of the pond will be planted with pots to make maintenance easier. We will include pink Nymphaea capensis, Nymphaea lotus (which flowers during the day here - go figure!) and hopefully Nymphaea petersiana. That will give us the full spectrum of native South African waterlilies.

Profile - Jacques Gerber | The Pond January 2003

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