Nelisiwe Khusi 1, Rita Liebenberg 1, Dr Donovan Kotze 2
1 Gouritz Cluster Biosphere Reserve (GCBR),2 Barry Street, Riversdale, 6670, Western Cape
2 Centre for Water Resources Research, University of KwaZulu-Natal
1. Broomvlei Wetland Overview
The Broomvlei wetland, located in the upper reaches of the Goukou River within the Breede-Gouritz Water Management Area (WMA), is a vital ecological zone. This unchannelled valley-bottom wetland, characterized by one of the largest peat deposits in the Fynbos Biome and dominated by palmiet (Prionium serratum), supports a diverse array of indigenous wetland plants along its margins. Broomvlei plays a critical role in biodiversity conservation, hosting endemic species and contributing to the ecological integrity of the broader catchment area. The headwaters of the Goukou River system originate in the protected Langeberg-East Mountain Catchment Area, a region recognized as a Strategic Surface Water Source Area. This area is essential for supplying water to local farmers downstream and the Stilbaai Estuary, a significant fish sanctuary and tourism destination that forms part of the Stilbaai Marine Protected Area. Moreover, the upper Goukou River is designated as a river Freshwater Ecosystem Priority Area (FEPA) supporting species such as the Cape kurper (Sandelia capensis), and Cape galaxias (Galaxias zebratus), and it is the only known habitat of the narrow-range endemic fish Galaxias sp. nov. ‘Goukou’ classified as Vulnerable.
2. Challenges: Alien Plant Invasion
The spread of Black wattle (Acacia mearnsii) poses significant threats to the Broomvlei Wetland, including:
- Bank Erosion: Alien plants destabilize riverbanks, leading to erosion and altered water flow.
- Water Quality: Erosion causes sedimentation, degrading water quality and harming aquatic habitats.
- Desiccation: Black wattle dries out the wetland, reducing its water and carbon storage capacity.
- Loss of Indigenous Vegetation: Black wattle outcompetes indigenous plants, reducing biodiversity and weakening ecosystem resilience.
- Biodiversity Loss: Habitat degradation threatens species like Galaxias sp. nov. ‘Goukou’, Cape kurper, and Cape galaxias
Above: A compromised section of the wetland has channelized, causing the redirection of water flow and leading to the drying out of the wetland (Captured August 2023).
Above: Sections of the wetland drying out; areas once covered by palmiet are now dominated by bracken fern (Captured August 2023 ).
3. Restoration Activities in the Broomvlei Wetland
The Broomvlei wetland is a key focal site for the Gouritz Resilient Rivers Project, which was initiated in 2018.
Wetland Restoration Goals:
- Restore ecological integrity.
- Promote indigenous plant growth and stabilize riverbanks.
Strategy:
- Invasive Plant Clearing: Focus on removing alien species.
- Biomass Utilization: Use chipped biomass as mulch to retain soil moisture, suppress weeds, and enrich soil.
- Indigenous Reintroduction: Plant indigenous species identified during baseline assessments such as: Grewia occidentalis, Searsia lucida, Carissa macrocarpa, Carissa bispinosa, Dodonaea viscosa var. angustifolia, Pittosporum viridiflorum, Olea europaea, Wachendorfia thyrsiflora, Gymnosporia buxifolia, and Searsia lancea
4. Monitoring and Evaluation
- Baseline Assessment: Conduct baseline assessments at strategic areas identified to determine vegetation composition, cover abundance, and soil organic matter content since March 2024
- River Health Monitoring: Aquatic biomonitoring along the Goukou River system using SASS5 and mini-SASS has been conducted since December 2023, with sites monitored seasonally
- Fish Monitoring: Assessing the distribution of endemic and invasive fish species along the Goukou river system in collaboration with the Grootvadersbosch Conservancy and the South African Institute of Aquatic Biodiversity (NRF-SAIAB) , conducted in December 2023 and February 2024.
5. Conclusions
Restoring the Broomvlei wetland is critical for conserving its rich biodiversity and maintaining the health of the Goukou River catchment. Active management, including the clearing of invasive species, replanting of indigenous vegetation, and continuous monitoring efforts, contributes to the long-term resilience and sustainability of the ecosystem. These restoration activities not only protect vulnerable species like Galaxias sp. nov. ‘Goukou’, but also support water security and regional ecological health, including the integrity of the Goukou estuary and fish sanctuary in the Stilbaai Marine Protected Area.
6. References
Chakona, A. 2017. Galaxias sp. nov. ‘Goukou’. The IUCN Red List of Threatened Species 2017: e.T107626097A107626289. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T107626097A107626289.en. Accessed on 16 October 2024.
Le Maitre, DC, Walsdorff, A, Cape, L, Seyler, H, Audouin, M, Smith-Adao, L, Nel, JA and Holland, M. 2018. Strategic Water Source Areas: Management Framework and Implementation Guidelines for Planners and Managers. TT 754/2/18. Water Research Commission, Pretoria,South Africa.
Nel, JL, Murray, KM, Maherry, AM, Petersen, CP, Roux, DJ, Driver, A, Hill, L, Van Deventer, H, Funke, N and Swartz, ER. 2011. Technical report for the national freshwater ecosystem priority areas project. Water Research Commission Report 1081 (2): 11.
Pool-Stanvliet, R, Duffell-Canham, A, Pence, G and Smart, R. 2017. The Western Cape Biodiversity Spatial Plan Handbook. Stellenbosch: CapeNature.
7. Acknowledgements
The following teams are acknowledged for their contribution to the restoration activities: the contracting teams for clearing under Louw Willemse, Pierre Kellies, Jacobus Vaaltyn and André Goliath; and the restoration team — Mark Jantjies, Lee-Ann Pretorius, Yaaseen Bodhanya, Leila Moosajee, Somila Liwani, and Purnille Albertyn.