By Nelisiwe Khusi, Donovan Kotze, Lee-Ann Pretorius
GCBR monitoring team, Lee-Ann, Claude, and Nelisiwe recently visited Ladismith to monitor an area that has been cleared of hakea and other invasive alien plants since 2019. The clearing was initiated by volunteers from the Mountain Club of South Africa and sponsored temporary farm workers, with support from local businesses including Ladismith Cheese, Lactalis, as well as the GCBR.
Since the clearing initiative began, 686 hectares of the Swartbergspruit catchment have been cleared, with more than 80 000 hakea trees cut down. The monitoring site is located downstream of where most of the clearing has occurred and, together with Ladismith town further downstream, is benefitting from water that has been freed up through this clearing. For both the town and the aquatic ecosystem, these benefits are likely to be most pronounced during droughts.
We were joined by Dr. Donovan Kotze, Hugh Sussens, and Samantha Adey from the Mountain Club of South Africa. During the visit, Donovan, Lee-Ann, and Claude identified indigenous fynbos plants along the riparian zone, while Nelisiwe carried out the SASS 5 and fish surveys with help from Hugh and Samantha.
Riparian Vegetation
Lee-Ann and Claude had an interesting session with Dr. Donovan Kotze looking at the plant species that occur along the riparian zone. He also demonstrated how to identify species and what to look for when taking pictures to assist with the plant identification.
The site is in a beautiful natural state, dominated by characteristic species such as Brachylaena neriifolia, Morella serrata, and Freylinia lanceolata, Lobostemon paniculatus and is free of invasive alien plants. Among the many interesting species found here is Erica afra, which is associated with the riparian zone. An interesting fact about the Erica afra is that it grows taller than most other ericas, especially along the riparian zone.
Fish and Macroinvertebrate Monitoring
This area is a vital water source for the Ladismith community and is home to the Slender redfin (Pseudobarbus tenuis), a near-threatened freshwater fish. The clearing work and ongoing monitoring play a crucial role in safeguarding their habitat while also supporting water security for the community, highlighting the importance of conservation for both biodiversity and people.
The water in this section of the Swartberg River was clear and did not have the typical brownish tint caused by dissolved organic matter, specifically tannins and humic substances, which we often see in rivers in our region, making it easy for us to see the samples we collected.
Hugh took pictures of some of the macroinvertebrates we identified on-site. Take a look at the photos to see some of the cool facts and fascinating features of these freshwater species.
References
Gerber, A., & Gabriel, M.J.M. (2002). A Guide to the Identification of Aquatic Invertebrates in South African Rivers. Department of Water Affairs, South Africa.
Fry, C. (2021). A Field Guide to Freshwater Macroinvertebrates of Southern Africa