Rivers and Estuaries Programme
Photo credit: Brittany Arendse
The southern Cape region of South Africa is home to a diverse array of rivers and estuaries that play a crucial role in supporting local ecosystems and communities. Given that South Africa is an arid country with an average rainfall far below the global average, the level of freshwater supply to water systems such as these rivers and estuaries is low. These systems, though, are known as biodiversity hotspots with estuaries providing important habitats for many species, supporting a number of estuarine-dependent endemic species. However, given their importance to society, these systems are also subject to intense human pressure. When combined with the impacts of climate change, this scenario is bound to cause a decline in water quality.
The southern Cape waterways, including the Keurbooms, Bitou, Salt (East) and Groot (West) rivers, are characterized by their unique ecological features, including rich biodiversity and important habitat for various species of insects, fish, birds, and plants. NVT is actively involved in research and conservation efforts focused on the Salt and Groot rivers and estuaries. This research includes monitoring water quality, studying the impacts of invasive species on native flora and fauna, and assessing the ecological health of these vital ecosystems. By conducting research and implementing targeted conservation measures, we aim to protect and restore these southern Cape rivers and estuaries, ensuring their long-term sustainability and the preservation of their valuable natural resources.
Recognising this, the Cape Estuaries Programme, a provincial government initiative, is working with local authorities, government organisations, non-government organisations and civil society to establish estuary management forums in the province. To this end, the NVT was a key partner in the establishment of the Salt River and Groot River Estuary Forum.
The aim of NVT’s rivers and estuaries programme is to develop a source-to-sea understanding of the Salt (East) and Groot (West) River systems and to conserve these systems. Both are considered to be of high importance. The Salt River is home to several yet unnamed freshwater invertebrate species which have been a subject of research in collaboration with Rhodes University, while the Groot River is one of the most pristine systems in the province and is home to two near-threatened and endemic fish species (Eastern Cape Redfin and the Cape Kurper). A new source-to-sea project for the Salt River is currently in its initial stages.
The Trust’s three projects that form part of this programme include a recently implemented source-to-sea project on the Salt River and the monthly monitoring of water quality and waterbirds along the Groot River Estuary. A fourth project, aimed at understanding frog diversity in the area, was recently added to explore a previously unstudied topic in the area. NVT also hopes to report on an exciting new PhD study planned as part of its rivers and estuaries programme in 2024.
Groot River (West)
The Groot River is a cherished natural resource in the southern Cape of South Africa. Its beauty, ecological significance, and recreational opportunities make it a notable part of the region’s natural heritage, deserving of conservation efforts to preserve its unique features for future generations. Monitoring rivers and estuaries is of paramount importance in understanding and safeguarding the health of these critical ecosystems. NVT conducts regular “health” assessments of the Groot River and its estuary within the Tsitsikamma section of the Garden Route National Park. This not only involves sampling to assess water quality by way of standardised methods but also assessing mainly fish and bird species with a view to informing management plans for the area.
Fish monitoring surveys provide valuable insights into the abundance, diversity, and distribution of fish species, allowing researchers to assess the ecological integrity of rivers and estuaries. By tracking changes in fish populations over time, scientists can identify trends, detect the presence of invasive species, and evaluate the effectiveness of conservation measures.
Native fish monitoring
Estuaries are regarded as one of the most productive environments on earth and are known to support several estuarine-dependent endemic species. In collaboration with SANParks, we monitor marine fish use of the Groot River Estuary, netting fish four times a year to assess which species utilize the estuary. This enables us to determine the structural and functional properties of the estuary fish community, providing an effective method of assessing the estuary’s ecological condition. The estuary has been identified as a key nursery ground for the endemic Cape Stumpnose and plays a role in hosting endangered species such as the estuarine pipefish, the over-exploited and vulnerable White Steenbrass, Leervis and Spotted Grunter. Given that the Groot River estuary is a temporarily open/closed system, ongoing monitoring can be indicative of the estuary’s ecological condition and provide for better management strategies.
Alien Fish Monitoring
Given that an alien fish species (the invasive Western Mosquitofish) has been introduced to the Groot River estuary, it is necessary to assess how this has affected endemic species and, ultimately, species composition so that direct pressures on native species, if any, can be managed and alleviated. Monthly sampling at 11 sites for Western Mosquitofish revealed seasonal patterns of abundance, and potential hotspots or refugia that sustain this species. Data collected over a span of four years is currently being analysed and will be subjected to peer review before being published. It is anticipated that the outcome of this study will aid the relevant authorities in taking decisions on how best to manage the estuary.
Coordinated Waterbird Count
Coordinated waterbird counts contribute to our understanding of the ecological dynamics within rivers and estuaries. These surveys help identify important feeding, breeding, and resting areas for waterbirds, providing vital information for habitat conservation and management. By monitoring waterbird populations, researchers can also detect changes in their abundance and behaviour, serving as indicators of the overall ecological health of these ecosystems.
Monthly bird counts are conducted in and around the Groot River and its estuary to determine the system’s life-supporting potential. This data is fed into the citizen science platform CWAC (coordinated waterbird count) hosted by the University of Cape Town to add to the long-term database for the area – a database that stretches over 15 years.
Overall, the bird numbers along the Groot River estuary seem stable with a varied assortment. 421 bird sightings were recorded between March 2022 and February 2023. This project is also an important monitoring component to assess the health of the system, and we will continue with the addition of monitoring along the Salt River system.
To compile a comprehensive Groot River report, some of the topics to be covered in future research will involve monitoring invertebrates and assessing the impact of bridges as well as estuary usage.
Photo credit: Tiaan Botha
Water quality measurements are essential for assessing the chemical, physical, and biological characteristics of rivers and estuaries. By monitoring parameters such as nutrient levels, pH, dissolved oxygen, and pollution sources, we can identify potential threats to water quality and determine the impacts on aquatic organisms and overall ecosystem health. Regular water quality assessments provide critical data for effective decision-making, pollution prevention, and the development of appropriate management strategies.
Collectively, these monitoring efforts contribute to a comprehensive understanding of the status and dynamics of rivers and estuaries. By informing conservation and management practices, such monitoring programmes enable timely interventions, help prevent degradation, and support the restoration of these vital aquatic ecosystems. Ultimately, the data obtained from fish surveys, coordinated waterbird counts, and water quality measurements play a crucial role in ensuring the long-term preservation and sustainable use of rivers and estuaries for both ecological integrity and the well-being of local communities.
Salt River (East)
The Salt River (East) is a significant natural resource in the southern Cape region, contributing to the region’s beauty, ecological diversity, and the well-being of local communities. Its conservation is essential to safeguard the river’s health, preserve its unique features, and maintain the delicate balance of the surrounding ecosystem for future generations to enjoy.
Flowing eastwards, it traverses through diverse landscapes, including rugged mountains, rolling hills, and fertile valleys. The Salt River is renowned for its unique characteristics and ecological importance. It provides vital habitats for various species of flora and fauna, including newly identified macro-invertebrate species representative of Gondwanaland relicts, birds, and amphibians. The river also plays a crucial role in the local community and has high recreational value.
Conservation efforts in the area aim to protect the integrity of the Salt River and its surroundings. These initiatives focus on maintaining water quality, managing invasive species, and preserving the natural habitats along the river’s course.
The Salt River project, funded through the Whitley Fund for Nature, will embark on a 2-year multidisciplinary study of the river catchment, from the source into the sea, to determine the baseline ecological health of the system, its value as a carbon sink, mechanisms that contribute to the functioning of the system, the threats, their drivers, and actions required to restore, maintain and improve the resilience of these ecosystems to deliver effective ecosystem services.
The project aim is to establish stakeholder-driven forums that conserve, manage and enhance sustainable economic and social use of catchments without compromising the ecological integrity and functioning of ecosystems.
The project kicked off in January 2023 and has since assembled a steering committee, conducted a public stakeholder meeting at the end of March 2023 to introduce the project and to co-define the setting for the Salt River project, and has finalised research topics and sourcing service providers to assist in more specialised studies. A key aspect of the project is the development of a framework/replicable model that can be used to restore and conserve other river systems in the area. The steering committee will continue to meet at regular intervals and the first research results are expected by the end of 2023.
The Salt River Source to Sea project is an integrated approach to river catchment research, focusing on nature-based solutions and community engagement. Through this initiative, the aim is to protect and restore the health of the Salt River and its surrounding ecosystems, ensuring the long-term sustainability of this vital waterway and promoting the well-being of local communities that depend on it.
The programme will apply the overarching framework of six essential steps for planning NBS at landscape levels: Co-define setting, understand challenges, create visions and scenarios, assess potential impacts, develop solution strategies, and realize and monitor.
This multidisciplinary team will be engaged to connect with stakeholders and implement baseline monitoring, to assess:
- Water quality and compliance with water quality standards
- Levels of existing and proposed water extraction
- Biodiversity and threats thereof
- A Citizen Science project with a focus on frogs will be established to sustain ongoing monitoring and encourage ownership and engagement with the process.
- Level of alien invasive plants and clearing requirements
- At-risk bird colonies
- Carbon load/stock
- Analysis and valuation of the ecosystem services within the landscape
- Comprehensive water quality monitoring (such as nutrient levels, pollution sources, flow, and sedimentation rates).
- Improved/ regular biodiversity surveys (including monitoring fish populations, macroinvertebrates, waterbirds and aquatic vegetation).
- Invasive species management (understanding the spread and impact of invasive species, developing effective management strategies, and evaluating the success of control measures).
- Investigate the impacts of climate change, including changes in flow regimes, sea-level rise, and increased frequency of extreme events.
- Restoration and rehabilitation to improve water quality, enhance habitat connectivity, and promote the recovery of degraded ecosystems.
- Socio-economic assessments and understanding of the human dimensions of conservation (i.e. social and economic value of these ecosystems, assess the impacts of conservation measures on local communities, and explore sustainable livelihood opportunities associated with river and estuarine resources).
- Inform policy development and promote better coordination among stakeholders involved in the management of these catchments.
- Education and awareness campaigns promoting behavioural change and fostering a sense of stewardship among local communities.