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Cape Critical Rivers Project monitors water quality

Written by Janice M on . Posted in Water & Environmental

A Worthwhile Project – Healthy Rivers Project by the Endangered Wildlife Trust

ewt_logoRivers form the lifeblood of our existence and protecting these crucial ecosystems is becoming more and more critical as economic development and growing populations require increasing amounts of water. Throughout Southern Africa, freshwater ecosystems are under severe pressure with more than 80% of South Africa’s rivers being threatened.

The Endangered Wildlife Trust’s Source to Sea Programme is working to conserve National Freshwater Priority Areas (NFEPAs) through Biodiversity Stewardship, integrated catchment management, strengthening of compliance and enforcement, education and awareness raising and the development of alternative livelihoods via the “green economy”.


  • Freshwater biodiversity is THE over-riding conservation priority during the International Decade for Action – ‘Water for Life’ – 2005 to 2015
  • A systematic assessment of river biodiversity in South Africa found that 84% of river ecosystems are threatened with 54% critically endangered
  • South Africa’s river ecosystems are under more pressure than its terrestrial ecosystems

The Cape Critical Rivers Project

The Cape Floristic Region (CFR) of South Africa is recognised as an area of exceptional biodiversity and species endemism. The CFR freshwater ecosystems together with their riparian corridors (on river banks), support a diverse assemblage of aquatic and terrestrial organisms, including the Riverine Rabbit and 43 freshwater fish species, 90 % of which are endemic and 60 % threatened.

This project focuses on two catchments – the Breede-Tradouw and the Olifants-Doring – the latter extending into the Succulent Karoo Biodiversity Hotspot.  Both of these catchments are very high priority areas for freshwater species conservation in Africa (Darwall et al. 2011) and support 17 species of freshwater fish, of which 70 % are endemic and 76% threatened.


Threats to both catchments include:

  • threats to river integrity;
  • inadequate water use governance
  • lack of awareness
  • alien fish invasion
  • inadequate research and monitoring.

The conservation actions proposed in this project have already been well-defined through Biodiversity Species Management Plans for two flagship freshwater species (Clanwilliam sandfish and Barrydale redfin), and thus this project will fulfill existing actions which cannot be implemented currently due to severe capacity constraints of the responsible agencies.

Bonnie Schumann, Senior Field Officer at the Drylands Conservation Programme, helping with a sandfish survey (March 2013)

Bonnie Schumann, Senior Field Officer at the Drylands Conservation Programme, helping with a sandfish survey (March 2013)

Threats to the target indigenous fish species are:

    • Loss of riverine ecosystem integrity or health through various non-sustainable land-use practices, such as abstraction of too much water for agricultural purposes or abstraction of water at the wrong time of year; bulldozing or changing the profile of the riverbanks; poor management of riparian zones, including overgrazing of riparian vegetation; poor protection of wetlands

    • Introduction and spread of alien invasive fish species

    • Incapacitated and under-resourced conservation and water governance, resulting in poor management of water use in critical catchments

    • Lack of awareness around the need to preserve ecosystems and the biodiversity they support

More about the indigeous fish in the Breede-Tradouw and the Olifants-Doring:

The target species are all indigenous fish species that naturally occur in these river catchments and are highly threatened by alien invasive fish species, which can either outcompete them or predate heavily on them.  The freshwater fish fauna of the Olifants-Doring Rivers Basin is in fact remarkable for its diversity and high levels of endemism. Out of the ten freshwater fish species that occur here, eight are entirely endemic to the basin itself. All eight are red-listed by the IUCN, including the Clanwilliam sandfish Labeo seeberi (Endangered), Clanwilliam sawfin Barbus serra (Endangered) and Clanwilliam yellowfish Labeobarbus capensis (Vulnerable) (IUCN 2010). The scientific and conservation value of these species is inestimable and they form an important component of the freshwater biodiversity of the Cape Floristic Region.

A tributary supporting endangered fish species

A tributary supporting endangered fish species

Very worryingly, there is no recruitment of young fish in these main stem rivers anymore, and therefore the only viable recruiting populations of all the endemic fish species are in tributary refugia upstream of the upper limit of alien fish invasion.

Exacerbating the threats from alien invasive fish species are excessive agricultural and domestic demands on water resources in this arid to semi-arid region and poor farming practices, especially along the riparian belts of rivers.  Some of the indigenous fish species, such as the Barrydale redfin and the Olifants sandfish, are hanging on by their last fins in just a few small sanctuaries where alien fish haven’t yet penetrated the system, and we are working to protect these last few refuges by trying to prevent further alien fish introductions and by mitigating other threats, such as water quality deterioration and lack of compliance with the Ecological Reserve.

If we lose these fish, it would be forever – they occur nowhere else in the world and play a unique role in the ecosystem, for example, sandfish are detritivores, grazing on the murky bits on rocks and the bottom of rivers, thus playing an integral role in keeping rivers clean. We have already lost the amazing sandfish migrations that have been recorded by farmers in the past as ‘watching the river go black with thousands of fish moving en masse to spawning grounds’.

Our project is based on the necessity to implement conservation actions to address the threats. Many of the actions needed have already been discussed and agreed upon by stakeholders but were not being implemented because of limited capacity and resources.

The Cape Critical Rivers Project aims to:

  •  firstly consolidate extant populations by reducing the risks of further invasions by alien fish species, especially in the Oorlogskloof-Koebee sanctuary;
  • reduce the risks posed by increasing water demand and unsustainable land management practices in all catchments;
  • increase knowledge of indigenous fish biology and ecology
  • improve knowledge of alien and indigenous fish distribution and spread
  • identify strategies to ensure landowner cooperation in preventing further disruption of the riverine ecosystem and try reduce the probability of further alien fish introductions
  • develop a case study to try encourage sustainable water management amongst stakeholders
  • identify strategies to improve cooperative water governance
  • improve habitat conditions for indigenous fish species
  • monitor and encourage compliance of the Ecological Reserve in the targeted catchment areas
  • Identify priority areas in Olifants sandfish original distribution range which can be cleared of alien fish, allowing for re-introduction of the species


  • Clanwilliam yellowfish are fairly big fish, sought after by anglers and a beautiful gold gleaming colour. They are strong swimmers, enabling them to undertake long migrations upstream during spawning.
  • The Clanwilliam sawfin grows up to a half-metre in length and depends on clear fast-flowing water to lay its eggs – this was only discovered because a freshwater fish expert (a partner collaborating on this project) undertook his PhD to discover where these fish spawned – this entailed diving for miles and miles upstream, surveying different fish habitats, watching fish for hours, and looking for tiny fish eggs.
  •  The Twee River redfin has the smallest distribution of any fish in South Africa – occurring only in the main stem and tributaries of the Twee River. Closely related to it is the Clanwilliam redfin which grows quite large.
  • Unfortunately we know so little about these fish species’ biology, nobody even knows where the Olifants sandfish spawns. We are predicting it will probably be in productive reaches of the river in fast-flowing water, but we only an inkling of its ecology.

Selectech is excited to be able to participate in this project by donating two PCSTESTR 35 multi-parameter pocket testers for monitoring of water quality in the rivers.

Dr. Martine Jordaan, an aquatic scientist at CapeNature, taking water quality measurements in one of the streams (March 2013)

Dr. Martine Jordaan, an aquatic scientist at CapeNature, taking water quality measurements in one of the streams (March 2013)

The PCSTestr 35 monitors the following parameters in water:
  • pH
  • Conductivity
  • Total Dissolved Solids (TDS)
  • Salinity
  • Temperature

With thanks to Bridget Corrigan, Source to Sea Programme Manager.

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