Post by Emma Oliver and Bridget Pitt

Recent visitors to Princess Vlei might have seen our star Hyacinth hunters at work. Sydney Jacobs and his team, working in collaboration with the City, have pulled off a small miracle in clearing this sprawling invader.
    Water hyacinth is an ‘invader’ from South America. Water primrose, which is growing amongst the hyacinth, and Typha Capensis, the long reeds or bulrushes are indigenous, but their vigorous growth can make them invasive.
    These plants, in particular water hyacinth and water primrose, are a growing threat to our waterways and wetlands. Hyacinth reproduces through seeds and runners, and can double its growth in days. The seeds fall into the water ensuring it reproduces the following year. Unchecked, it covers the water in a dense carpet, blocking sunlight and oxygen, and killing aquatic life below.
    These invaders are a major headache for the City of Cape Town in managing their wetlands. The challenges are two fold:  removing the plants from the water faster than they can grow, and removing this biomass from the banks — without destroying the banks and biodiversity in the wetlands. At Princess Vlei, the City has previously relied solely on mechanical removal, which was extremely expensive, damaging to the banks and leading to disasters where our restoration sites were destroyed, plus ineffective as the hyacinth rapidly grew back in the months during Western Leopard Toad breeding season when operations had to cease.

With the injection of funds channeled to Princess Vlei through Nature Connect, and donor funding raised by the Forum, we met with role players from the City in November last year to draw up a strategy for dealing with the hyacinth. This included the use of hand teams operating from the banks and shore, the use of bioagents, mechanical removal from the shoreline and an amphibious weed harvester to remove growth from the water body.
    Action was launched with the release of bio agents by the Invasive Species Unit in December last year, in a controlled area at the inlet to the vlei. The Forum’s contribution is the ‘Green’ boat team, sourced and managed by local eco champion Sydney Jacobs. We purchased three boats, a motor, and gear such as waders, life jackets and cutters. Sydney, who also works at Zeekoevlei, is a genius at effective operations, and fashioned a ‘hyacinth plough’ to push clumps of hyacinth to the shoreline, as well as crafting specialized long necked rakes. By the end of January this year, the team was ready to roll.
    The boat team’s operation is simple but extremely effective. The team cut the hyacinth into squares, working from the boats or in waders from the shore. The motorised boat, the ‘Princess’, pushes these squares to the shoreline, where they are removed by hand or by machine and piled on the shore. The piles are removed by trucks contracted by the City.

The Forum has raised funds for 80 days of labour with the Green team — we are currently at day 55. So far 120 truckloads of hyacinth have been removed off site by the CSRM (Catchment and Stormwater River Management).  The Green team, often up to their waists in the water, cut loose the hyacinth and the boat pushes it out towards the long arm excavator for removal. This week, with the long arm properly in action for the first time, it has been exciting to see the master plan working as per our original design. The machine has hugely accelerated the rate at which hyacinth can be moved, and in a few days created 8 mountainous piles of hyacinth and water primrose on the banks.
    The biomass is taken to a dump an hour’s drive away as it has been declared too toxic for the landfill site at Muizenberg, only 7 kilometres south. Since the water quality at Princess Vlei is the cleanest of all the Vleis, this seems unnecessary and is slowing up the rate at which the biomass can be removed.
The Invasive Species Unit (ISU) have provided labour on the shoreline for removing the biomass, as well as their biocontrol programme. This deploys the megamelus bug and another weevil to feed on the hyacinth and assist in its elimination. The ISU progress was slowed by an invasion of painted reed frogs in their breeding tunnels, which were eating the megamelus. They had to remove these well-fed frogs and start again with the bug breeding programme. It is back on track now and the placement and impact of the bio agents is being monitored. More ‘bugs’ or bio agents have been ordered from Rhodes University, which is where they are sourced, to up their numbers in Cape Town. With bugs, it’s a numbers game and more equals better hyacinth elimination.
    Now that the long arm excavator is working, it has been exciting to see how effective this strategy is, coming at less than a tenth of the cost of a fully mechanised removal. However, critical elements promised by the City have not been delivered. The Long arm excavator came late to operations and the long-awaited weed harvester has not yet materialised. We are awaiting a boom at the inlet, promised for this week.
    Thanks to our combined initiative, the City now has a clear hyacinth management plan, and we are grateful to Cllr Southgate and various city officials for the progress made so far.  However the Forum has been the main driver for achieving the plan, and our green team works longer and harder than City deployed labour. This experience illustrates again that GPVCA cannot effectively be managed by different City departments without over sight. These leads to a lack of co-ordination by different departments, and sometimes disasters due to unsupervised contractors. We need one person to oversee what happens to both the water body and the land on this site. We hope that this experience will spur the City to more effective management strategies and delivery and will persuade the various role players that management under the Biodiversity Management Branch would be far more suited to this important wetland.
    To conclude on a happier note, nature continues to reward any investment made. With cleared banks and access to the water, the moorhens, darters, cormorants, herons, malachite and pied kingfishers, Egyptian geese and sacred Ibis are all more present. The birds love the new perches – the head and platform of the floating Princess are a favourite spot to hang out, as are the three boats, used by the Green team, and anchored permanently in the middle of the Vlei. We will continue to lobby the City to up its investment, plan ahead and ensure that all this work is sustained in the future

• Photographs by Sydney Jacobs, Kamva Nose, Jane Doherty and Bridget Pitt
• This project is made possible through funding by the Hans Hoheisen Charitable Trust managed by Nedbank Private Wealth
  
• Read more about this project
  

  ‘The river was our mother, and just as you would never harm your mother so we were careful never to harm the river. There was a lot of indigenous wisdom about the rivers’ - Sicelo Mbatha, reflecting on the values he learnt as a child.

This is the message of our Source to Sea project. The project aims to help young people to understand the value of rivers, to our ecosystem, our biodiversity, our physical and spiritual health. The Princess Vlei Forum has designed a workbook with a series of observational and reflective exercises to focus the learner’s journey to understanding rivers.
    A group of high school learners from Manenberg is joining us on a journey to study the length of the Diep River - at it’s source, at the point where it enters the Little Princess Vlei, when it has been canalised, and the estuary at Sandvlei when it enters the ocean.
     On March 29, fourteen teenagers from the Manenberg based ‘Brave Rock Girls’ organisation, went up to Cecilia Waterfall, which is near the source of the Diep River on Table Mountain. We set off on a misty morning, for many the first time they had walked on this iconic Cape Town mountain.

On the way up, we looked at the river, and noticed how it moved rapidly down the mountain, tumbling over the rocks and small waterfalls. We spoke about the indigenous trees growing nearby, and the impact of our history and colonialism on our rivers and forests.
      After an hour of uphill hiking, we reached the waterfall. This perennial waterfall is a perfect place to study moss forests, and the life they support such as the tiny Moss Frog. Learners studied the moss plants through magnifying ‘loupes’ to see the intricate and delicate foliage, and tried to identify the different plants.
      The outing was educational but above all a fun and energetic experience for all, giving learners a good insight into how the Diep River begins its journey to the sea. Further excursions will enable the learners to study the river at different stages of this journey.

• Photos by Robin Moodley and Bridget Pitt
• Thanks to the National Lotteries Commission for funding this project.