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M.Sc. (Zoology) Please refer to full text to view abstract

MSc (Zoology), North-West University, Potchefstroom Campus, 2015 In this study, fish were used as bio-indicators to evaluate the present ecological state (PES) in different reaches of the Senqu River downstream of the proposed Polihali Dam in Lesotho. However, information regarding fish of the Senqu River is limited, although the various Lesotho fish species received attention with the introduction of trout populations in the 1930s to 1960s. In the 1960s fishery studies and research shifted towards the biology and ecology of local species, with particular attention paid to the endangered Maluti minnow (Pseudobarbus quathlambae) and the migration of cyprinids from the lower Senqu/Orange River into Lesotho in order to spawn. However, there was renewed interest in the fish species of Lesotho with the launch of the Lesotho Highlands Water Project (LHWP) during the late 1990s. After considering the approaches established in Phase I and the outcome of the use of fish to contribute to the establishment of the ecological water requirements (EWR) for the construction of the Katse and Mohale Dams, the research project team decided to use fish as ecological indicators to evaluate the PES prior to the launch of Phase II of the LHWP which entails the construction of the Polihali Dam. Seventeen fish species are known to occur in the upper Orange/Senqu River and its tributaries. These include the longfin eel (Anguilla mossambica) that was able to migrate from spawning sites in the Atlantic Ocean up the Orange River into Lesotho. Due to the establishment of many dams acting as barriers to their migration in South Africa, the access to different habitats has now been restricted in the Senqu River in Lesotho, and in the Orange River in particular. Other indigenous fishes include the now protected Maluti minnow and the rock catfish (Austroglanis sclateri) (both of which have established permanent populations within Lesotho), the Orange-Vaal River mudfish (Labeo capensis), Orange-Vaal River smallmouth yellowfish (Labeobarbus aeneus), Orange-Vaal River largemouth yellowfish (Labeobarbus kimberleyensis) and the moggel (Labeo umbratus). Until recently large numbers of all these species migrated from the middle reaches of the Orange River into the Senqu River and its tributaries. Although many individuals of these cyprinids still migrate into the Senqu River from South Africa, today as much as 90% of their migration potential is disrupted due to a series of partial barriers in the Orange/Senqu River. In addition, seven more indigenous fishes occurred in the lower reaches of the Senqu River in Lesotho and still occur in the upper Orange River catchment. These include the chubbyhead barb (Barbus anoplus), goldie barb (Barbus pallidus), straightfin barb (Barbus paludinosus), threespot barb (Barbus trimaculatus), sharptooth catfish (Clarias gariepinus), southern mouthbrooder (Pseudocrenilabrus philander) and banded tilapia (Tilapia sparrmanii). Three alien species, the rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and common carp (Cyprinus carpio) were successfully introduced into Lesotho where they have established populations. Prior to the launch of Phase II of the Lesotho Highlands Water Project, an evaluation of the combined impacts of this development on the Senqu River and its fish was required to minimize the effect of this development on the receiving environment. To achieve this, the aim of this study was to determine the effects of flow and temperature changes on the attributes of fish in the Senqu River, using multiple lines of evidence (LoE). The latter included the use of established best scientific practice measures, or tools across multiple levels of biological organisation. Therefore the objectives of this study were to: 1. Determine the influence of flow and temperature changes on the recruitment of cyprinids in the Senqu River (Chapter 2). 2. Determine direct and indirect effects of flow alterations on the feeding biology of selected fish of the Senqu River (Chapter 2). 3. Use population structures to evaluate the wellbeing of fish communities in the Senqu River (Chapter 2). 4. Use the habitat preferences and migration requirements of fish to evaluate the effects of flow alterations in the Senqu River (Chapter 3). 5. Use the Fish Response Assessment Index (FRAI) and shifts in community structures of fish to evaluate the effects of anthropogenic activities in the Senqu River (Chapter 4). In this study, a winter survey (August 2013) and a summer survey (January 2014) were carried out on four main sites on the Senqu River and on one site on the Linakeng River. Seven species of fish were observed during the 207 electro-fishing and netting efforts carried out on the more than 1 km long reach of each site. In total, 692 smallmouth yellowfish, 154 rock catfish, 145 mudfish, seven juvenile moggel, seven sharptooth catfish and two largemouth yellowfish were collected. Trout are still common in the study areas and 44 rainbow trout were collected. In addition to the fish diversity assessments, information on the population structures, recruitment, feeding ecology, and habitat requirements of the fish was gathered and evaluated during the surveys. The data gathered during these surveys were compared to available historical data to evaluate the state of the local fish communities at each site. These outcomes revealed that the state of the fish communities in the study area has deteriorated to a moderately modified state in the Senqu River downstream of the Polihali Dam site (sites IFR P1 and IFR P2), and to a moderately modified to largely modified state downstream of the confluence of the Senqu and Malibamatso Rivers below the Katse Dam, and at the confluence of the Senqu and Senqunyane Rivers below the Mohale Dam (sites IFR 5 and IFR 6). In particular, the state of the fish communities at site IFR P1 directly downstream of the proposed site of the Polihali Dam has deteriorated to a moderately modified state. Main determinants (or driver variables) contributing to the altered state of the fish communities at this site were identified as habitat state alterations – including sedimentation and a reduction in cover features – and the effect of barriers on the upstream migration of cyprinids, in particular in the Upper Orange River and Lower Senqu River. Likewise, the state of the fish communities at site IFR P2 was observed to occur in a moderately modified state (slightly worse than IFR P1). In similar fashion, the main drivers contributing to the altered state of the fish communities at this site included habitat template modifications, reduction in the abundance of cover features and the effect of barriers on the migration of cyprinids in summer. The state of the fish communities at site IFR 5 has deteriorated to a moderately modified to largely modified state. Main drivers responsible for this include modifications to the distribution and abundance of velocity-depth habitat types associated with altered flows from the Katse Dam, upstream land-use practices primarily impacting the site during winter and summer, and the effect of barriers on upstream migrations of cyprinids. Interestingly, in the vicinity of site IFR 5, it was found that some adult yellowfish and mudfish individuals maintain viable populations in the Senqu River and do not migrate into the lower reaches of the river or into the Orange River in South Africa. The state of the fish communities at site IFR 6 was also observed to be in a moderately modified to largely modified state (worse in winter). Here the extensive alterations to instream habitats – particularly substrate types – have reduced the average depth, and altered the flowdependent habitat profiles at the site. Downstream barriers were again identified as important driver variables affecting the wellbeing of fish. Based on this information, together with additional historical and regional evidence, recruitment data, feeding biology data and habitat preference data, the IFR (instream flow requirement) for the fish could be determined. In addition, the FRAI was used to assess the integrity of the fish communities. Recruitment data were obtained by determining the age of larval smallmouth yellowfish, mudfish, rock catfish and rainbow trout. Winter recruitment was evident for smallmouth yellowfish, mudfish and rock catfish between April and June, and from November to December during the summer. Rainbow trout recruitment was evident in September. Data on the feeding biology of rock catfish indicated that they rely more on macroinvertebrates as food source in winter, whereas smallmouth yellowfish rely more on algae and diatoms as food source in summer periods. Environmental variables such as flows, depths, substrata and temperatures were recorded for each site in the study. Throughout this process, these multiple variable flow requirement states were used to establish aspects of the volume, timing and duration of flows required to maintain the local fish communities. These aspects included base flows required to maintain suitable habitats for recruitment and resident fish, flows that provide key ecological cues for species, and flood flows to maintain key ecological processes. Masters

M.Sc. (Zoology) Please refer to full text to view abstract

D.Sc. (Zoology) The spermatogenesis of two freshwater species from South Africa, Barbus marequensis and B. polylepis, and three fresh water species from Israel, B. canis, B. longiceps and Capoeta damascina, was studied. A histological comparison of the process of spermatogenesis was undertaken. The breeding cycle of B. marequensis, B. polylepis, B. canis, B. longiceps and C. damascina was similar to the breeding cycle of B. aeneus and four phases occured within the cycle. The four distinctive phases are post spawning phase, rest phase, pre-spawning phase and the spawning phase (Vlok, 1986) . During the post spawning phase a decline in sperm development is observed and possible lisosomal activity is responsible for the resorption of sperm cells not shed during the spawning phase. The presence of collagen structure provides a distinctive character to the tissue of the testis. The resting phase is characterised by the absence of the lobular structure and the testis is dominated by the collagen tissue. The testis is small and unobtrusive in the abdominal cavities of both species. At the onset of the pre-spawning phase, the testis is filled with spermatogonia. The lobular structure becomes more prominent and the interstitial tissue can be distinguished. Later during the phase, the synchronised development of sperm cells in the cysts of the lobules can be observed, whilst sperm cells in adjacent lobules are in different stages of development. During the spawning phase the testis of all species studied contain mature sperm . cells in the lumens of the lobules.

M.Sc. (Zoology) Milt and blood samples of Aarbus aeneus were collected during November in order to perform chemical analyses of the blood and seminal plasma. Physical analyses were also carried out on milt. Throughout the year testes were collected in order to determine the stages of testicular development. This was done by means of histological analyses. The sperm counts averaged 8,41 x 10-3 cells rom while the spermatocrit value varied between 44% and 82% (average of 61,9%). All the milt samples collected were white in colour showing a high viscosity. Sperm motility gradually declined after activation and stopped after 82,5 seconds. Chemical values of the components tested in the blood plasma were statistically compared to those in the seminal plasma and no statistically significant differences were recorded between sodium, potassium, chloride, calcium, magnesium, glucose, total lipid, total proteien concentrations, osmolality and pH. The only component where a difference in concentration occured was fructose (30% probability). Sodium, calcium, magnesium, glucose, fructose, total lipid and total proteien concentrations in the blood plasma were significantly lower than the corresponding concentrations in the seminal plasma. In contrast the potassium concentration were higher in the seminal plasma. The pH of the seminal plasma (8,63) was alkaline while a pH of 7,5 was recorded for blood plasma. In the two lobe testis of Barbus aeneus semen is collected with seminiferous ducts into the vas deferens which together with the blood vessels are housed within a hilus. The testis is surrounded by a tunica albugenea and the seminiferous lobules are filled with cysts. The testis of the smallmouth yellowfish appears to be lobular and sperm are deposited into lumens which exist between the cysts. During the resting phase the interstitial tissue is very difficult to distinguish and is seen as a thin layer of cells between the lobules seperating them from one another...

Fishes are widely used by biologist as ecological indicators that measure key elements of complex systems, without having to capture the full complexity of a specific system. The Vaal River in South Africa is classified as Africa’s hardest working river and is home to, two yellowfish species that are socially and economically important. Both these yellowfish species are considered to be sensitive to changes in water quantity and quality, habitat destruction and utilisation pressure and are often used as ecological indicators to manage aquatic ecosystems. Very little however, is known about their movement, response to changing environmental variables and interspecies habitat preferences. This study therefore aims to use radio telemetry as a method to characterise and evaluate how yellowfish behaviour is influenced by changing environmental variables. To characterise the behavioural ecology of the Vaal-Orange River yellowfish species in lentic and lotic ecosystems, Labeobarbus aeneus (n=18) and L. kimberleyensis (n=3) were fitted with externally attached radio transmitters in Boskop Dam (L. aeneus, n=4) and the Vaal River (L. aeneus, n=14) (L. kimberleyensis, n=3). Various methods were used to collect yellowfish species including: gill nets, to target mobile individuals, in deep habitats, electro-fishing (electro-narcosis) to collect yellowfish in shallow habitats and angling techniques in a wide variety of habitats. Thereafter yellowfish species were sedated and tagged with externally attached radio transmitters, before being released back into the system. Yellowfish were monitored for eleven months using a remote monitoring system together with manual monitoring surveys. Analyses of data collected showed that L. aeneus follows distinct behavioural patterns, with some individual variations in behaviour. Labeobarbus aeneus exhibited higher movement that are associated with deeper water during daylight hours (04:00-16:00). During nocturnal periods (20:00-04:00) L. aeneus showed a decrease in movement activity and preferred shallower water compared to daytime. However, L. aeneus in the Vaal River seems to be less influenced by bright daylight and this might be due to the turbidity of the river water. Labeobarbus aeneus in Boskop Dam showed higher movement counts during full moon phases whereas L. aeneus in the Vaal River showed higher movement counts during new moon phases. All tagged fishes in Boskop Dam and in the Vaal River preferred deeper water during full moon phases than during new moon phases. Movement were significantly higher (P

M.Sc. Two yellowfish species, namely Labeobarbus aeneus and Labeobarbus kimberlyensis were collected in the Vaal Dam and Vaal River Barrage over two years. The macroscopic characteristics, such as dimension and weight were recorded prior to dissecting out the gills. The gills were examined using a stereomicroscope for Paradiplozoon sp., the number of parasites was recorded and they were flat-fixed and stored in 10% Neutral Buffered Formalin. Statistical analysis of host yellowfish dimension and weight, and Paradiplozoon sp. occurrence was performed using Statistical Processing Software Suite v.15.00. The seasonal variation in size and shape of adult life-stage Paradiplozoon sp. attachment clamp sclerites was investigated using the geometric morphometric software Morphologika2 v. 2.5. Water quality variables at the Vaal Dam and Vaal River Barrage were analyzed using RAU Water v.2 software to produce a final Aquatic Toxicity Index Solway aggregate score. Diporpa, juvenile and adult stages of Paradiplozoon sp. were collected from yellowfish in the Vaal Dam, and oncomiracidia were allowed to hatch from eggs that were maintained in vitro. Details of life-stages were examined and measured using light microscopy, epi-fluorescence microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The Solway aggregate score indicated that the water quality score in the Vaal Dam was better than the Vaal River Barrage. The water quality score was the poorest at both sites in the summer and best during the winter. Turbidity was identified to be the poorest water quality variable. No Paradiplozoon specimens were recovered from the gills of fish from 2005 to 2007 in the Vaal River Barrage. The numbers of Paradiplozoon sp. on yellowfish in the Vaal Dam were the greatest in winter at 67% prevalence, when the water quality score was the best during the study. In contrast to the elevated diplozoid numbers in rivers of poorer water quality in Europe, a low number of Paradiplozoon sp. were collected in spring when the water quality was poorer. This may be attributed to the difference in the type of aquatic pollutant in the Vaal River and European rivers. Yellowfish were longest and heaviest during spring, followed by autumn, summer and winter. It was not possible to statistically prove whether the presence of Paradiplozoon sp. negatively influences the size and weight of yellowfish. The increase in weight is suggested to be as a result of increased fat reserves, prior to spawning in spring.

M.Sc. The practice of catch-and-release (C&R) fishing has been widely promoted as a conservation strategy and fisheries management tool and is currently considered an ecologically sustainable practice. Factors negatively affecting fish as well as mortality have, however been shown to occur. The overall aims of this study were to determine the effect of C&R angling on tigerfish Hydrocynus vittatus and Vaal-Orange smallmouth yellowfish Labeobarbus aeneus by studying the physiological stress response as well as age, growth and reproductive characteristics. To determine the physiological response of tigerfish (n=63) and smallmouth yellowfish (n=96) data were collected during August/September 2008 (Okavango Delta) and from June 2008 through to December 2008 (Vaal River) for the respective species. Fish were collected using standard angling and fly-fishing techniques, anaesthetised in clove oil and blood drawn from the caudal veins; thereafter fish were weighed and measured, revived and released. To serve as controls, randomly selected fish (from each species) were kept for 72 h in pools filled with river water. Blood plasma was analysed for concentrations of glucose, cortisol and lactate to determine the effects of angling duration, fish size, and water temperature. In both species larger fish were shown to be angled for a longer duration compared to smaller fish. Levels of glucose, at times, were affected by water temperature (influenced by time of year). Plasma glucose concentrations in H. vittatus showed a slight increase whereas levels in L. aeneus decreased with greater angling durations. Few individuals from each species, (n=13 for H. vittatus and n=12 L. aeneus) showed significantly increased plasma cortisol concentrations. Lactate concentrations were found to increase significantly above control values in H. vittatus angled for < 1 min and L. aeneus angled for > 1 min. Increased handling durations of captured H. vittatus that had been angled for < 1 min showed a significant increase in plasma lactate concentrations. Results from the control fish indicated that baseline levels of lactate in H. vittatus and cortisol and lactate in L. aeneus were restored within 72 h of capture. The relative age of the selected species were determined with the aid of scales, lapillus otoliths (H. vittatus) and asteriscus otoliths (L. aeneus) The most appropriate methods found for ageing the two species were sectioned lapillus otoliths for H vittatus and whole asteriscus otoliths for L. aeneus. Males and females from both species were found throughout the age classes. Male and female H. vittatus had a longevity of 20 years and 16 years respectively, similarly, male and female L. aeneus had longevities of 19 years and 15 years respectively (relative age for both species). Summary 11 Hydrocynus vittatus males matured at a total length (TL) of 451mm and females matured at 522mm TL, corresponding to an approximate relative age of 4 years for both sexes. Labeobarbus aeneus males matured at a fork length (FL) of 289mm and females matured at 367mm FL, corresponding to relative ages of 4 and 6 years respectively. This is the first study of its type reporting on the physiological response of African freshwater game fish species as well as the first report of age determination of H vittatus in the Okavango Delta and the first for this species using otoliths. While the age of various L. aeneus populations have been studied this is the first time that otoliths are used in the Vaal River population. This study confirms that the physiological response, and potential negative effects of C&R are species specific, and that studies should be done on all targeted freshwater game fish species to ascertain the physiological stress imposed by C&R angling.