Category Archive River health

Let the fish swim : send Matt and Céline to Australia !

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Tales of a 6-months internship with the AER Team by Emily Winter

Emily Winter shares some of the highlights of her six-month internship with the Aquatic Ecosystem Research Group.

Back in April, I was pleased to be met with a welcoming and enthusiastic group at UKZN, who readily introducing me to the research themes, team members and field sites. I was eager to challenge myself and quickly got stuck into some fish surgery practice with Céline and Matthew, in preparation for the FishTrack project in the uMngeni catchment. I soon overcame my fear of croc-infested waters and could be found checking nets and electro-fishing at Fountain Hill Estate in search of the Natal yellowfish. I was excited to be assisting Matthew and co in the development of their new, real-time telemetry project.

Assisting Matt in catching yellow fish in Fountainhill Estate (Wartburg)

While also assisting with the quarterly REMP (River Eco Status Monitoring Programme) surveys, my own project was developing under the watchful eyes of Gordon and Celine, and in June I joined the SAPPI team to explore the lower Thukela catchment and monitor its fish and invertebrate communities. A hypothesis was born, and I focussed my investigations on the use of the Nembe and eMandeni tributaries by fish when the Thukela river is in flux. My fish identification and surveying skills progressed rapidly with the support of Mahomed, particularly in distinguishing between the small barb (Enteromius) species, and I was proud to be able to lead similar surveys in July and August. The opportunity to survey the Thukela fishway with Gordon, David and Mphatheni was a particular highlight, with initial results suggesting that the structure does not function as a migration corridor as well as would be hoped.

Conducting REMP surveys in the Umgeni with Fortunate and Pumla.

In the final few months, I was very fortunate to be invited to contribute towards international efforts for a review paper on African fish migrations (yet to be published). The experience has been invaluable in developing my scientific critique, writing and collaboration skills and I have learnt a considerable amount about African freshwater ecology in the process. Despite returning to Europe, I am excited about continuing this trend, maintaining connections with my new South African friends and colleagues, and developing ways in which we can work together in the future. With the help of Mahomed, I will be remotely completing the ‘Tributary Refuge’ project on the Thukela and I look forward to sharing the results with the wider research community when the time comes.

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A survey in the Pungwe

During February and July 2017, Mahomed Desai, senior researcher and PhD candidate was part of a team that undertook an ecological survey within a selected area of the Pungwe Catchment in Mozambique.

Figure 1 3D Layout of the Pungwe Basin (Tinley, 1977)

The Pungwe River is shared between Mozambique (95% of the basin, generating 65-70% of the runoff) and Zimbabwe (5% of the basin, generating 30-35% of the runoff). The Pungwe River and its associated tributaries are highly dynamic and possess a relatively high diversity of habitat and biotope types, possibly due to the geomorphological nature of the system. The Pungwe mainstem can be described as torrential and is possibly due to the predominance of bedrock in the system as well as the topographical nature of the catchment. However, the river widens and flattens as it traverses the southern tip of the African Rift Valley – See Figures 2 and 3.

Figure 2 The southern tip of the East African Rift Valley system (WildCam Lab, 2017)

Figure 3 Photographs illustrating the Pungwe River (clockwise from top left) – Upstream view from the boundary of the Rift Valley during the low flow season; downstream view from the boundary of the Rift Valley during the low flow season; the Pungwe Gorge wherein the entire river is constrained into a relatively narrow gorge (to get an idea of the scale the depth off the edge was greater than 7 m) and deploying a fyke net in the Pungwe River (the bridge in the background is the boundary of the Rift Valley)
One of the major tributaries of the Pungwe River within the survey area is the Muazi River. The river is also bedrock-dominated (Figure 4). During the low flow season the turbidity of the system reduces and supports a population of Hydrostachys polymorpha, a rheophilic aquatic macrophyte (Figure 4). The species is currently listed as ‘Vulnerable’ and plays an important role in supporting an array of aquatic biota. In addition, within the survey area there are numerous creeks with a gravel and sand thalweg that drain into the system (Figure 4). These creeks provide a refuge area for various aquatic biota but these are however seasonal. Nevertheless, during low or zero flow periods there are isolated pools connected by sub-surface flow that provide habitat.

Figure 4 Photographs illustrating the Muazi River, a major tributary of the Pungwe River (clockwise from top left) – Downstream view exhibiting rapid-pool complex typical of the reach; angling in a large active channel pool; underwater photograph illustrating Hydrostachys polymorpha, an aquatic macrophyte listed as ‘Vulnerable and one of the numerous creeks that drain into the Muazi River (only isolated pools connected by sub-surface flow present during the low flow season)
As a consequence of the relatively high diversity of habitat types and biotopes within the system, including the survey area, the region supports a relatively high level of biodiversity, both terrestrial and aquatic. Of special interest within a regional context are the ichthyofauna, Odonata and terrestrial insects. These organisms although not as visible as other ‘charismatic’ species such as birds or larger mammals nevertheless are important in maintaining ecosystem processes and thereby overall wellbeing. A total of 38 species of ichthyofauna were recorded during both seasonal surveys and were typical of the Zambezian fauna. The dominant families were Cyprinidae, Mochokidae and Mormyridae. The ichthyofauna and formed unique communities within the system based on availability of cover features and substrate preferences, per redundancy analyses. Figure 5 illustrates some of the species recorded within the survey area.

Figure 5 Examples of the ichthyofauna of the survey area (clockwise from top left) Cyphomyrus discorynchus; Syndodontis zambezensis; Zaireichthys rotundiceps; Opsaridium zambezense; Marcusenius macrolepidotus and Hydrocynus vittatus

In addition, a new species or species complex of Chiloglanis (Mochokidae W. K. H. Peters, 1868) was recorded for the survey area (Figure 6). The species was typically associated with rapids and runs and utilised aquatic macrophytes, rocky crevices and cobble/boulder substrates as cover. Although data does not exist on dietary requirements, based on closely related species, it is assumed to feed on “aufwuchs” or the periphyton and invertebrate community that inhabit sold surfaces of lotic systems.

Figure 6 Top row – Photographs illustrating the lateral (left) and ventral view (right) of Chiloglanis sp. nov. Bottom row – Boxplot indicating catch per unit effort of Chiloglanis sp. nov. across hydraulic biotopes sampled. Dark horizontal line represents the median value, whisker represents 95th percentile and dots represent outliers
Due to the characteristics and size of the system as well as its inherent biodiversity, the system provides an array of ecosystem services to local communities and to society within a larger regional context. These services are varied and include subsistence fisheries, sediment deposition for agriculture, raw materials and pest control amongst others (Figure 7). However, no formal quantitative or qualitative studies have been undertaken and these are postulated based on previous knowledge from other systems and observations during the survey periods. Therefore, future research of this subject within the region should be considered if funding is available.

Figure 7 Examples of the range of ecosystem services provided by the Pungwe system (clockwise from top left) Fish trap made from reeds used during the high flow season; fish trap used during low flow periods; subsistence fishing is an important activity for local communities; maize fields in floodplain; Odonata are important pest-control agents and raw materials harvested for construction

Although the region possesses a substantial level of biodiversity the only formally protected area is Gorongosa National Park (GNP), located within the Lower Pungwe River. The Pungwe River delineates the southern boundary of GNP (Figure 8). Seasonal flooding from the Pungwe inundates shallow pans and oxbow channels on the Rift Valley plain at the southern end of the park. This flooding is vital for the newly constructed 6200 ha wildlife sanctuary near Chitengo and the DingeDinge Marshes at the confluence of the Pungwe and Urema rivers. During the high flow season, the Pungwe River branches and forms the Nhanvu River that flows into the Urema River upstream of Lake Urema and subsequently the Muaredze River before joining back into the Pungwe River. During the dry season, the Nhanvu River transforms into a series of pans (Figure 8). Nevertheless, these pans perform a vital function by providing refuge and/or nursery habitats evidenced by the relative abundance of Enteromius species, including E. haasianus, and juvenile life-stages of species recorded within the respective pans during the survey (Figure 8). During the high flow season when connectivity to the Pungwe River is restored, species are able to disperse and colonise new available habitat. Therefore, the connectivity between the pans and the Pungwe River is regarded as critical to maintain the wellbeing of the local ichthyofauna population.

Figure 8 Photos to illustrate the Pungwe River at Gorongosa National Park (clockwise from top left) Pungwe River during sunset; one of the pans fed by the Pungwe River via the Nhanvu River during high flows; pans linked to the Pungwe via the Nhanvu River are important refuge and nursery areas once isolated during the low flow season and Crocodylus niloticus at Lake Urema

At present, there are no significant water resources development projects in the Pungwe River basin in Mozambique. However, demand to harness Pungwe waters for inter-basin water transfer, municipal water supply, salinity control, hydropower, flood mitigation, large irrigated agriculture (sugar) schemes, and other uses is increasing. Furthermore, unsustainable use of the system and its catchment is leading to a decline in biodiversity and ecosystem wellbeing. Given the substantial socio-ecological importance of the system, it must be sustainably managed in a holistic manner involving all stakeholders as well as formally conserved in key areas.

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Sampling through the cold front

The team started off the River Eco-status Monitoring Program (REMP) second quarter (July-September, 2017) with the Thugela and uMngeni River catchments. The Thugela catchment team headed for central KZN and included the Mkomazana river along Sani pass. While the Umgeni team surveyed along the uMngeni River with a few sites in the Mlazi River. It so happened that a cold front swept over the province during the week of surveying creating magnificence views of KwaZulu-Natal back-dropped by the Drakensburg mountains covered in snow. The front made for some interesting weather to survey in with cold winds and temperatures.

The survey went well and even contributed to some of the genetic work the AER is doing on barbs Enteromius sp and freshwater eels, Anguilla sp.

In total 3 eels were caught, one on the Mooi River upstream from the Mooi-Thukela confluence and two on the Mlazi. All the eels were Anguilla mossambicus.  Eight E. anoplus were caught on the Mkomazana River near Sani Pass, while ever hopefull of catching the Maloti minnouw (Pseudobarbus quathlambae) there. Other barbs, E. gurneyi were caught on the Karkloof river in the Umgeni Catchment.

With over 3000km driven so far the REMP second quarter is off to a good start. We still have the southern and northern sites to do.

First field trip for our new team members !

It is time again for another River Health Programme round. Gordon and Céline, accompanied by the brand new team members, Carla Higgs, Mphatheni Mthembu and Fortunate Mashaphu conducted a site survey in the Umkomazana Catchment on the 09th February 2017.

Carla Higgs is one of our new PhD Students and she will focus her projects on ecological risk. Mphateni and Fortunate are master students who will respectively work in fisheries/river health and aquaculture. It was the occasion for our new members to train themselves in the field.

Gordon teaching Carla about SASS

Teaching how to use a clarity tube

The Umkomazana catchment is situated down Sani Pass, North of Himeville in KwaZulu Natal. It is one of major tributaries to the Umkomaas River, which enters it from the South. It has a longer upland valley section than the main river or its Northern tributaries, the Loteni and Inzinga. The Umkomazana River is a pool drop mountain stream and is 16 km in length. This entity once held a critical endangered cyprinid, the Maloti minnow, Pseudobarbus quathlambae and at the time it was recorded as showing a dramatic decline in population size following the introduction of trout to its habitat.  This species is now known to exist in six isolated Alpine populations in tributaries to the Orange River, Lesotho. The purpose of the survey was to conduct a survey (fish, invertebrates, diatoms, vegetation and water quality) in the framework of the River Health Program.

The team collected, measured, identified and recorded fish and invertebrates specimen. Presence of chubbyhead barb (Enteromius anoplus) is to be noted. DNA samples were collected for further analysis.

Welcome !

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INVITATION – Dialogue to celebrate the World Fisheries Day and workshop on SA Fish Swimway Programme

We are pleased to announce that the SA Fish Swimway Programme will be hosting a workshop on the 21st of November 2016 in Pretoria. The University of KwaZulu Natal, together with WRC and SA Fish Swimway Programme Partners, will be hosting an event to celebrate World Fisheries Day. This will include presentations by fish specialists, followed by discussions reviewing the Swimway programme and refining the next steps. One of the speakers will be Mathew Ross, who in 2015 completed his PhD on fishway design in South Africa.  Representatives from the Kingfisher Project have also been invited, to talk about the current plans for Catchment Management Agencies in South Africa. During the workshop, we would like to specifically refine a suitable proposal that can be used for funding applications relating to fish migration in South Africa. We hope you will be able to attend ! 

Interested ? Please RSVP events@wrc.co.za

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River Health Programme : Surveys in Northern KZN

While the fieldwork and draft report has been completed for the November 2014 to March 2016 increment of the River Health Programme, another round of sampling has been completed in September/October 2016. Specimens were collected, identified, DNA samples collected and biotope features where each species was collected was recorded.

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The W Primary Catchment – From the Umhlathuze to the uSuthu

The W Primary catchment is located in Northern KZN and spans from the Umhlathuze to the uSuthu River. A total of 17 sites are located in this area, with many being ecologically important due to presence of a relatively high level of freshwater biodiversity and species endemism for the province.

The area is not only important for freshwater biodiversity but terrestrial biodiversity as well.

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Many of the systems within the area were completely dry or not flowing due to the intense drought the country is presently experiencing.

However, some of the sites that retained pools were identified as important refuge areas for several species of fish as well as Odonates.

Key examples of this include a site on the Nwaku River that comprised of a series of pools where a total of 304 individuals from 6 species were recorded. Species recorded included Pseudocrenilabrus philander as well as the recently red-listed Enteromius gurneyi. 

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(c) christian Fry

 

Another important example was the site located on the Sikwebezi River. At this site the local landowner was fortunately supplying the system with surface water from his storage dam otherwise the site would have been completely dry.

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Thanks to his efforts in maintaining water in the system, a total of 167 individual fish were recorded, including juveniles of migratory species such as Labeo molybdinus and Labeobarbus natalensis.

Although some systems were possessed no flows, some of the larger systems were flowing and were identified as important areas for fish populations. Unfortunately, due to time constraints these sites were not sampled as comprehensively as warranted and the intention is to re-visit these sites to obtain a better understanding of the fish populations they possess. This included the sites on the Umhlathuze River as well as sites located within the Phongolo catchment. Below are some of the species that were recorded for these sites.

 

Unfortunately, many of the sites within the area were negatively impacted from anthropogenic activities and influences such as industry, illegal sand-mining, solid waste and over-grazing.

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Considering that society needs the ecosystem goods and services that freshwater ecosystems supply, it is critical that we effectively and sustainably manage the way we use our natural resources to ensure an optimum balance between protection and use. Education is also important if we are to ensure the protection of these vital ecosystems for the benefit of all.

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