Philosophiae Doctor - PhD (Biodiversity and Conservation Biology)

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Characterisation, Isolation, Purification and Toxigenicity ofDiplodiatoxin produced by Stenocarpella maydis in Maize
(University of the Western Cape, 2002) Rao, Shailaja Kishan; Rees, D Jasper G
Mycotoxins attract worldwide attention because of the significant economic losses associated with their impact on human health, animal productivity, domestic and international trade. Over 300 mycotoxins have been discovered, of which a few are of serious concern (Smith and Moss 1985; Rheeder et al., 1994). Exposure to these mycotoxins can produce both acute and chronic effects ranging from death to effects upon the central nervous, cardiovascular, pulmonary systems and upon the alimentary tract. Mycotoxins may be carcinogenic, mutagenic, teratogenic and immunosuppressive (Ferrante et al., 2002). Mycotoxins are currently considered as a major problem in developing countries (Miller, 1994).
Salt tolerance and modification of wheat salt resistance by plant hormones
(University of the Western Cape, 2004) Adam, Muftah Ahmed; Raitt, Lincoln; Aalbers, Johannes
The history of salt tolerance and the factors effecting salt resistance of plants were literature surveyed, and it was concluded that ion concentration, salt accumulation, compatible solutes and the genetic traits play a major role in the salt tolerance of plants. Differences in salt resistance of wheat cultivars were investigated at the germination and early seedling stages. Considerable intervarietal differences in salt resistance between wheat cultivars were reported. The interaction between salinity and plant hormones was studied and showed that N6- benzyladinin treatments caused some changes in some parameters that were studies, GA3 treatments showed more effects on these parameters of salt stressed plants. This study showed that the treatment with some organic acids, citric acid and malic acid, did not cause significant changes in the parameters measured of the wheat plants. No effects on seed germination were due to the decreases in the pH value due to the GA3 treatment were found. The study concludes that treatment of salt stressed wheat cultivars with GA3 could alleviate some of harmful effects of high salt levels, and that it could be useful to treat plants grown in brackish soil or saline environment.
The Shallow water bryozoans of the West Coast of South Africa
(University of the Western Cape, 2005) Florence, Wayne Kevin; Gibbons, Mark
The South African biota is characterised by high levels of diversity and endemism. While commercially viable taxa have been well-studied, cryptic organisms such as bryozoans, have been neglected in terms of study. Taxonomic research on the South African Bryozoa has a brief and fragmented history. As a consequence most of the previous studies have focused on the south and east coasts of South Africa, and at depths deeper than 100 m. It is suggested that previous studies of the Bryozoa in South Africa have failed to reveal more than a fraction of the potential faunal complexity for this region. Earlier studies of the South African bryozoan fauna have described -255 species, mainly from the south and east coasts. The current study, therefore, attempts to identify and describe the shallow water bryozoan fauna from the west coast of South Africa and to compare the South African fauna with that of other regions. Specimens collected from localities, ranging from False Bay to Port Nolloth, along the west coast of South Africa, yielded 63 species, representing three orders (Cyclostomata, Ctenostomata and Cheilostomata), 32 families and 46 genera. Five species are cyclostomes, three are ctenostomes and 55 are cheilostomes. The ratio between the orders is not surprising considering the relatively low diversity of Cyclostomes and Ctenostomes in marine habitats. Thirteen species are new to science (-21% of the total species described in this study), of which seven species are found in seven genera (Eurystrotos, Klugeflustra, Thalamoporella, Bitectipora, Schizosmittina, Fenestrulina and Celleporina) that are newly reported from South Africa and thirteen species are reported from the west coast for the first time, of which one, Hippomonavella formosa, is a new record for South Africa. Including the species described here, approximately 269 valid species, representing three orders (Cyclostomata, Ctenostomata and Cheilostomata), 73 families, and 130 genera have been reported from South Africa. An accurate species number is not yet possible from this area as there are still outstanding problems with synonymies.
Linking biology and sustainable livelihoods to the proposed establishment of community -based Eucheumoid farming in southern Kenya
(University of the Western Cape, 2005) Wakibia, Joseph .G; Keats, Derek; Raitt, Lincoln; Bolton, John
Growth rates of three commercial eucheumoids: brown Eucheuma denticulatum and green and brown Kappaphycus alvarezii were studied at three sites (Gazi Bay, Kibuyuni and Mkwiro) in southern Kenya. The study was conducted using the fixed off-bottom rope technique over a 15 month period from August 2001 to October 2002, in 4 plots (5 m x 1.5 m) set up at each site. The brown E. denticulatum had the highest mean growth rate over the entire period of 4.7% day-I compared to the green and brown K. alvarezii which were 4.3% day l and 4.2% dayl, respectively. Mean relative growth rates were highest at Gazi (5.6% dayl), and lowest in Kibuyuni (3.2% day-I) with intermediate values of 4.8% dail at Mkwiro. Increased water motion was observed to increase thallus nitrogen and hence the growth of eucheumoids. The 'ice-ice' syndrome affected both brown E. denticulatum and brown K. alvarezii but not green K. alvarezii. Mean growth was higher during the southeast monsoon (4.7% day+) than during the northeast monsoon (4.0% dayl).The carrageenan characteristics of the three morphotypes were measured for 12 months. The highest carrageenan yield was obtained for green K. alvarezii (59.1% dry wt), whereas the average carrageenan yield for brown K. alvarezii was 56.5% dry wt and 56.6% dry wt for brown E. denticulatum. The plants at Gazi (58.0% dry wt) had a slightly, though significantly, higher carrageenan yield than both those at Kibuyuni (57.1 % dry wt) and Mkwiro (57.3% dry wt). However, from a commercial point of view the differences in carrageenan yields were not meaningful. Highest gel strengths were obtained in carrageenans from green K. alvarezii (1042.1 g cm") and brown K. alvarezii (1053.7 g ern"), whereas low values of 100.8 g ern" were obtained for brown E. denticulatum. The brown E. denticulatum had carrageenan with higher viscosity (81.7 mPa.s) and sulphate content (29.1% dry wt) than both green and brown K. alvarezii. The gel viscosities of all the morphotypes were higher during the southeast monsoon (67.3 mPa.s) than during the northeast monsoon (46.3 mPa.s) and were positively correlated with gel strengths.A survey was conducted among households in the three villages, from April to September 2001 to assess their socio-economic characteristics. There were 182 household heads interviewed; about 20% were women. Fishing was the main source of livelihood for about 48% of the household members. In 2001, the average monthly income for the surveyed households was Kshs. 9904 (1 US$=75 Kshs.), with about 67% having less than Kshs. 10 000. The average prevalence of poverty among the households surveyed was 45.1% with 38.8%,54.8% and 46.7% of households in Gazi, Kibuyuni and Mkwiro villages, respectively, living below the poverty line of Kshs. 1239 per month per adult person. An economic feasibility study for growing brown E. denticulatum and brown K. alvarezii in pilot farms of 0.1 ha was conducted at Gazi and Kibuyuni. A higher yield of 793 kg dry wt was obtained for plants grown at Gazi than those at Kibuyuni (793 kg dry wt). The net income derived from E. denticulatum was estimated at Kshs. 7549 annually in a 0.1 ha seaweed farm. A higher annual income of Kshs. 49 126 was generated from K. alvarezii. The rate of return on investment in farming E. denticulatum ranged from 15 to 63%, while 122 to 380% for K. alvarezii. The pay back period was shorter for the latter (0.3 to 0.7 years) than the former (1.2 to 2.7 years).A cross-sectoral policy analysis regarding legislation and policy relevant to the introduction and development of eucheumoid cultivation in Kenya, with particular reference to Kenyan legislation was conducted. The analysis showed that there is no system of promoting or regulating mariculture, though there are fragmented regulations that are scattered among the policies, Acts and regulations of various institutions. Such regulations were not designed specifically for mariculture and as a result they do not fully address the needs of mariculture. The establishment of a national mariculture development programme in Kenya is proposed as a means to develop and manage the farming of marine resources, including seaweeds.
A global revision of the nongeniculate coralling algal genere Porolithon Foslie (defunct) and Hydrolithon Foslie (Corallinales, Rhodophyta)
(University of the Western Cape, 2005) Maneveldt, Gavin W.; Keats, Derek; Weitz, Frans; Faculty of Science
The purpose of this thesis was to provide a revision and characterization of the species of nongeniculate coralline algae previously ascribed to the now defunct genus Porolithon; to provide a modern account of selected taxa from the genus Hydrolithon and descriptions of taxa found to conform the generic delimitation of Hydrolithon and to use a phenetic cluster analysis to determine the taxonomic relationships between the various taxa ascribed to the genera Polorithon and Hydrolithon.
The ecology of tadpoles in a temporary pond in the Western Cape with comparisons to other habitats
(University of the Western Cape, 2006) Hopkins, Samantha; Channing, Alan; Faculty of Science
This work centered on the tadpoles in a temporaray pond in the middle of Kenilworth racecourse, Cape Town, South Africa. Trapping was carried out over two wet seasons and five species were found. The racecourse was selected to investigate the tadpole community occupying temporary winter pools. The main focus of this study was the community of tadpoles that occur in the ephemeral ponds in the centre of Kenilworth Racecourse. This study was a very broad insight into tadpole ecology in the Western Cape.
Seasonal effects on the feeding ecology and habitat of Chersina Angulata in the South Western Cape
(University of the Western Cape, 2008) Joshua, Quinton Ignatius; Hofmeyr, Margaretha D.; Henen, Brian T.
Nearly one-third of the world’s tortoises live in South Africa, but little is known about their habitat requirements and feeding ecology. Chersina angulata, the angulate tortoise, is endemic to southern Africa, with a wide distribution along the western and southern coasts. Because this tortoise occupies a number of different habitat types, it has always been considered a generalist herbivore, although little is known about its diet and other needs. This study evaluates the habitat characteristics and feeding ecology of C. angulata at two study sites in the southwestern Cape, the West Coast National Park (WCNP) and Dassen Island (DI). The WCNP is a large conserved area in the Fynbos biome, along the southwestern coast of South Africa, whereas DI is a small offshore island with low floral and faunal diversity, just south of the WCNP. The efficacy of three methods used to study the feeding ecology of herbivores, focal observations, macroscopic faecal analysis and histological analysis of scats, was evaluated. Plant cover, species diversity, and the variety of growth forms were substantially larger at the WCNP than on DI. In the WCNP, shrubs and grasses were the dominant growth forms but the vegetation also included herbs, succulents, restios, sedges and parasitic plants. A few perennial species such as the grass Ehrharta villosa, shrubs such as Helichrysum niveum, Nylandtia spinosa and Rhus spp., and succulents such as Carpobrotus edulis and Ruschia spp., provided most of the plant cover. DI had a depauperate flora, consisting of succulents and herbs, and ephemeral plants contributed more than perennials did to plant cover throughout the year. The succulents Mesembryanthemum crystallinum and Tetragonia fruticosa provided most of the cover on DI. Angulate tortoises are herbivores and 72 diet plants in 32 plant families were identified to the species or genus level. Several diet species, however, could not be identified. In addition to angiosperms, the tortoises’ diet included mosses, mushrooms, insects,snails and animal faeces. The most important growth forms in the diet were herbs and grasses. The diet of the WCNP tortoises was more diverse than the diet of DI tortoises, but the number of principal food items in the diet did not differ between the two sites. Over an annual cycle, WCNP tortoises had four principal food plants while DI tortoises had five principal food plants. At both sites, principal food plants changed with the season and few plants remained principal food items in more than one season. Cynodon dactylon was a principal food item in three of the four seasons in the WCNP, whereas Trachyandra divaricata was a principal food plant each season on DI. Most principal food plants were grass or herb species but the sedge Ficinia nigrescens, and a succulent that could be identified only to the family level (Aizoaceae), featured strongly in the spring diets of DI and WCNP tortoises, respectively. The three study methods did not provide the same type or quality of information about the feeding ecology of angulate tortoises. The small size and wary nature of angulate tortoises compromised focal studies because it was often not possible to see what the tortoises ate. This method, however, provided the interesting observation that rabbit faecal pellets contributed nearly 30% to summer and autumn diets on DI when food was scarce. Rabbit faeces may not only provide a source of nutrients but may also supplement the microflora, required to digest cellulose, in the tortoises’ guts. Macroscopic evaluation of the tortoises’ scats appeared to be an ineffective method to identify diet plants, and the bulk of the scat mass could not be identified. This indicates that angulate tortoises either selected food low in fibrous content or that the digestive system of the tortoises dealt efficiently with tough plant material. The macroscopic method was the only method that highlighted the large contribution of fruits / seeds to the diet of angulate tortoises. Since the tortoises digested many seeds only partially, or not at all, C. angulata is potentially an important agent of seed dispersal in the southwestern Cape. The macroscopic study showed that on DI, sand made up 28% of the scat mass in spring, whereas sand never made a substantial contribution to the scat composition of WCNP tortoises. Lithophagy may be an important strategy in a depauperate habitat, such as DI, because the abrasive action of sand may help with the digestion of tough plants, or the sand may provide the tortoises with important minerals that are deficient in their food plants.The histological analysis of scats provided the most comprehensive diet list for C. angulata. Selection indices based on data from the histological analysis indicated that angulate tortoises were highly selective in their food choice. Most of the principal food items were selected out of proportion to their availability and the tortoises avoided the most abundant plants in their habitats. Several factors, such as palatability, accessibility and profitability, may have influenced their food choice. The proportional similarity indices for WCNP and DI tortoises, respectively, were 0.31 and 0.16, confirming that C. angulata is a food specialist and not a food generalist as was previously thought. This factor should be considered in the management of this species and in future conservation planning of its habitat.
A yeast 2-hybrid screen to identify and characterize interaction partners of the cancer associated protein Retinoblastoma binding protein 6
(University of the Western Cape, 2009) Chibi, Moredreck; Pugh, David JR
Retinoblastoma binding protein 6 (RBBP6) is a 250 kDa protein that is implicated in mRNA processing and ubiquitination functions and has been shown to be highly up-regulated in a number of cancers. In humans and mice, RBBP6 interacts with both tumour suppressors p53 and pRb, suggesting that it is involved in regulation of transcription, induction of apoptosis and cell cycle control. Knock-out of an RBBP6 homologue PACT resulted in p53 dependent cell cycle arrest and apoptosis. Although the biological functions of RBBP6 remain largely unclear, it is possible that its functions are mediated through interaction with other cellular proteins. Since it is possible to unveil novel functions of a target protein through identifying its interacting protein partners, this study aims to further characterize the functions of RBBP6 through identifying novel protein interacting partners using a yeast 2-hybrid screen. In order to identify interaction partners of RBBP6, two well characterized domains of RBBP6, the N-terminal ubiquitin-like DWNN domain and RING finger domain, were used as baits in a yeast 2-hybrid screen of a human testis cDNA library. Putative interactors were verified using in vitro and in vivo immunoprecipitation assays. The RING finger domain was shown to interact with transcriptional factors V-Box binding protein 1 (YB-1) and zinc finger and BTB containing protein 38 (zBTB38), resulting in their ubiquitination. In the case of YB-1 ubiquitination was correlated with a decrease in the intra-cellular levels of YB-1, suggesting that ubiquitination leads to degradation in the proteosome. The DWNN domain was shown to interact with a splicing associated small nuclear ribonucleoprotein polypeptide G (snRPG) and heat shock protein 70 (Hsp70). The results of this work suggest that, at least in the case of YB-1 and zBTB38, RBBP6 plays a role in the regulation of gene expression by ubiquitination of transcription factors, causing them to be degraded in the proteosome. The study provides further evidence of RBBP6's involvement in mRNA splicing through its interaction with snRPG. The interaction with Hsp70 suggests a possible role in protein quality control similar to that played by other E3 ligases such as Parkin and CHIP.
Impacts of degradation on critically endangered Oudtshoorn Gannaveld
(2010) Wheeler, Alan David; Knight, Richard
In the Succulent Karoo biome of South Africa vegetation degradation by overgrazing is a recognized threat to biodiversity. In the eastern Little Karoo region of the Western Cape Province, ostrich farming has degraded large areas of natural vegetation, particularly in the Gannaveld habitat of the Oudtshoorn basin. Little quantified vegetation data exists on the impacts of degradation and the composition of the Gannaveld vegetation types. This study quantifies the composition of Oudtshoorn Gannaveld and the impacts of degradation on this critically endangered vegetation type. The diversity of this vegetation type is added to by the occurrence of mima-like circular soil mounds, termitaria, which support distinctive plant assemblages. Perennial plant data and soil data were collected from the largest remaining remnant of Oudtshoorn Gannaveld perceived to contain different levels of degradation from near pristine to severely degraded. The results show 72 species in 49 genera and 17 families were recorded with the Aizoaceae, Asteraceae and Amaranthaceae families being dominant. The off termitaria plant community is dominated by the Asteraceae, Aizoaceae and Crassulaceae families while the on termitaria community is dominated by the Asteraceae, Amaranthaceae and Zygophyllaceae families. Four levels of degradation were identified in each of the broader on and off termitaria communities. It was found that grazing and trampling induced degradation on termitaria results in the loss of perennial plant cover and plant litter and an increase in bare ground while degradation off termitaria results in a loss of species. There are changes in soil chemistry both on and off termitaria as a result of vegetation degradation. Degradation results in palatable species being replaced by unpalatable and disturbance indicating species. Perennial plant cover off termitaria is resilient to grazing and trampling, however species richness, plant functional type composition and the abundance of individual species are not. Species richness on termitaria is resilient to grazing and trampling but cover, plant functional type composition and the abundance of individual species are not. Degradation results in shifts from succulent and woody shrub dominated communities to dwarf succulent and dwarf succulent shrub dominated communities. These changes hold implications for agriculture,biodiversity conservation and the provision of ecosystem services.
How do teachers and learners navigate the terrain of ecology and what are the associated conceptual understandings?
(University of the Western Cape, 2011) Raitt, Rosemary Ruth; Holtman, L.B.
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focussed on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The results of the misconceptions questionnaire for the PGCE students revealed that a high percentage of them had very little understanding of ecology and that they held several common misconceptions, despite having completed a degree which qualified them to teach Life Science or Natural Science in high school. This study demonstrated that more attention needs to be given to the proper training of Life Science teachers, and to instruction in practical work and fieldwork in the Life Sciences.
How do teachers and learners navigate the terrain of ecology and what are the associated conceptual understanding?
(2011) Raitt, Rosemary Ruth; Holtman, L.B
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focussed on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The questionnaire revealed that learners lacked an understanding of photosynthesis and respiration, which forms the basis for an understanding of food chains and energy flow within an ecosystem. Learners were confused about ecology and did not understand basic concepts. The misconceptions held in high school carried over to university, as shown by the fact that the first-year Life Science students, tested before they had had any lectures, still held many of the misconceptions that were found among the high school learners. A few second-year students still held misconceptions, but their understanding of photosynthesis and respiration was better than that of first-year students. The questionnaire also revealed that learners lack language skills. Good language skills are necessary for the development of scientific literacy.
An analysis of primary and secondary production in lake Kariba in a changing climate
(University of Western Cape, 2011) Ndebele-Murisa, Mzime R.; Musil, Charles; Raitt, Lincoln
Analysis of temperature, rainfall and evaporation records over a 44-year period spanning the years 1964 to 2008 indicates changes in the climate around Lake Kariba. Mean annual temperatures have increased by approximately 1.5oC, and pan evaporation rates by about 25%, with rainfall having declined by an average of 27.1 mm since 1964 at an average rate of 6.3 mm per decade. At the same time, lake water temperatures, evaporation rates, and water loss from the lake have increased, which have adversely affected lake water levels, nutrient and thermal dynamics. The most prominent influence of the changing climate on Lake Kariba has been a reduction in the lake water levels, averaging 9.5 m over the past two decades. These are associated with increased warming, reduced rainfall and diminished water and therefore nutrient inflow into the lake. The warmer climate has increased temperatures in the upper layers of lake water, the epilimnion, by an overall average of 1.9°C between 1965 and 2009. The warmer epilimnion has led to a more stable thermocline in the lake, and its upward migration from a previously reported 20 m depth to the current 2 to 5 m depth reported in the lake’s Sanyati Basin. A consequence of the more stable thermocline has been the trapping of greater amounts of nutrients in the deep, cold bottom waters of the lake, the hypolimnion, and this coupled with a shorter mixing (turnover) period is leading to reduced nutrient availability within the epilimnion. This is evident from a measured 50% reduction in nitrogen levels within the epilimnion, with phosphorus levels displaying a much smaller net decline due to localised sources of pollution inflows into the lake. These changes in lake thermal dynamics and density stratification have reduced the volume of the lake epilimnion by ~50%, which includes the well mixed, oxygenated euphotic zone leading to more acidic waters (lower pH) and increased water ionic concentrations (conductivity), and decreased dissolved oxygen levels, which have resulted in a 95% reduction in phytoplankton biomass and a 57% decline in primary production rates since the 1980s. The reduced nitrogen levels especially have contributed to a proliferation of nitrogen-fixing Cyanophyceae, the dominant Cylindrospermopsis raciborskii comprising up to 66% of the total phytoplankton biomass and 45.6% of the measured total phytoplankton cellular concentrations. Also, shifts in seasonal dominance of different phytoplankton groups have been observed in the lake during turnover, the Cyanophyceae having increased in dominance from 60% of the total phytoplankton biomass in the early 1980’s to the current 75%. In contrast, the Bacillariophyceae have declined substantially, from 18% of the total phytoplankton biomass in the early 1980’s to the current 1.7%. The diminished phytoplankton biomass of more palatable phytoplankton, and the proliferation of smaller, less palatable phytoplankton taxa, has resulted in reduced zooplankton biomass and species richness and altered zooplankton species composition. Concentrations of large Cladocera and Copepoda especially have declined substantially in the lake by up to 93.3% since the mid 1970s, with small Rotifera currently comprising 64% of the total zooplankton biomass. The reductions in zooplankton biomass correspond with recorded decreases in catches per unit effort for the sardine Limnothrissa miodon (Kapenta), which have been steadily declining in the lake since 1986.
How Do Teachers and Learners Navigate the Terrain of Ecology and What are the Associated Conceptual Understandings?
(University of the Western Cape, 2011) Raitt, Rosemary Ruth; Holtman, L.B.
This thesis relates the teaching of ecology in schools to the requirements of the National Curriculum Statements, Grades R-9 and Grades 10-12, for Natural and Life Sciences. It examines the conceptual understanding of the learners to determine their level of bioliteracy. The effectiveness of various teaching strategies in enhancing bioliteracy is considered. The study was a case study involving classroom observations of Grades 4 to 7 at a primary school and Grades 8 to 11 at a high school in the Western Cape of South Africa, and the administration of a misconceptions questionnaire to learners in Grades 8 to 11. The Department of Education did not allow researchers into the Grade 12 classes. To counter this, the misconceptions questionnaire was also administered to first-year Life Science students and to students in one second-year course in the Department of Biodiversity and Conservation Biology. It was administered to a small sample of the Postgraduate Certificate in Education (PGCE) students (prospective teachers) at the University of the Western Cape, in order to determine whether misconceptions would be carried into their teaching. In-depth interviews which focused on the particular student's misconceptions were used to verify the misconceptions which the first-year students held. The questionnaire revealed that learners lacked an understanding of photosynthesis and respiration, which forms the basis for an understanding of food chains and energy flow within an ecosystem. Learners were confused about ecology and did not understand basic concepts. The misconceptions held in high school carried over to university, as shown by the fact that the first-year Life Science students, tested before they had had any lectures, still held many of the misconceptions that were found among the high school learners. A few second-year students still held misconceptions, but their understanding of photosynthesis and respiration was better than that of first-year students. The questionnaire also revealed that learners lack language skills. Good language skills are necessary for the development of scientific literacy. Three of the seven teachers whose classes were observed admitted to finding it difficult to teach ecology. One of them suggested that the Department of Education provide special training to teachers in this area of teaching. Issues relevant to South African problems were not addressed in any of the classes observed. - Too-little time is allocated to the teaching of ecology to allow for any discussion of social issues relating to this subject. Time, resource constraints, and a lack of training in teaching ecology make it impossible for teachers to fulfil the requirements of the curriculum. Grade 10 learners were required to identify abiotic and biotic factors operating in a local ecosystem, and to describe the trophic relationships present. Grade 11 learners were required to study and report on one local example of human influence on the environment. These requirements were not met. While teachers were prepared to take learners out of the classroom to study ecology, some of them were not able to do so because of extremely large classes and associated problems. The results of the misconceptions questionnaire for the PGCE students revealed that a high percentage of them had very little understanding of ecology and that they held several common misconceptions, despite having completed a degree which qualified them to teach Life Science or Natural Science in high school. This study demonstrated that more attention needs to be given to the proper training of Life Science teachers, and to instruction in practical work and fieldwork in the Life Sciences.
Sources of heavy metals in vegetables in Cape Town and possible methods of remediation
(University of the Western Cape, 2012) Meerkotter, Marÿke; Raitt, Lincoln; Brendonck, L.; Dept. of Biodiversity and Conservation Biology; Faculty of Science
Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted.
Biochemical investigation of anti-cancer activity of Tulbaghia violacea
(UWC, 2012) Saibu, Gbemisola Morounke; Meyer, Mervin; Katerere, David
Natural products have been a source of many pharmaceutical drugs and a number of drugs that are currently used in the treatment of cancer are derivatives of compounds originally isolated from natural products. There is evidence that extracts of Tulbaghia violacea can be used to treat cancer. The activation of apoptosis in cancer cells is a target for the development of novel anti-cancer drugs since one of the characteristics of cancer cells is resistance to apoptosis due to the deregulation of biochemical pathways leading to apoptosis. In fact, many current anti-cancer drugs exert their effects through the activation of apoptosis. Previous studies showed that extracts of T.violacea induce apoptosis in cancer cells and one study reported on the isolation of a compound (methyl-ԃ-D-glucopyranoside), which is responsible for the pro-apoptotic activity of the T.violacea extract. Therefore the aim of this study was to investigate the anti-cancer activity of methyl-ԃ-Dglucopyranoside and extracts prepared from T.violacea. In this study the pro-apoptotic activity of methyl-ԃ-D-glucopyranoside and extracts prepared from T.violacea were investigated on a panel of human cancer cell lines, which included HepG2, MCF7, H157, HT29 and the non-cancerous cell line, KMST6. The induction of apoptosis was evaluated by flow cytometry using several bioassays which measures biochemical events (caspase activation, phosphatidylserine externalisation and reactive oxygen species (ROS) production that is associated with the induction of apoptosis. The results demonstrated that the effects of methyl--D-glucopyranoside on cultured cells are transient and that the cells recover from the effects of methyl--D-glucopyranoside. This suggested thatmethyl-ԃ-D-glucopyranoside is not the compound responsible for the pro-apoptotic bioactivity in the T.violacea extract. This study also showed that cytotoxic and pro-apoptotic bioactivity of the leaf-extract was significantly higher in comparison to the tuber-extract. The bioactivity of the organic solvent extracts (dichloromethane, hexane, methanol and 50% methanol/water) of T.violacea leaves was also significantly higher than water extracts of T.violacea leaves. A comparison of the different organic extracts prepared from the T.violacea leaves showed that the highest activity was observed for the dichloromethane and hexane extracts. In an effort to identify the bioactive compound(s) the dichloromethane extract was subjected to Versaflash® column chromatography. However, due to problems experienced with the solubility of the dichloromethane sub-fractions, these compounds could not be tested for their bioactivity. Palmitone (16-hentriacontanone) was identified as one of the major compounds present in the dichloromethane sub-fractions. This compound was previously shown to have anticonvulsant bioactivity but there is no evidence in the literature that it has anti-cancer or pro-apoptotic activities. Fingerprinting of the methanol extract showed the presence of long chain fatty acid derivatives, flavonoids and allicin derivatives in the methanol extract. Although, this study failed to isolate the pro-apoptotic bioactive compound(s) present in the extracts of T.violacea, it confirmed that extracts of this plant induce apoptosis in cultured human cancer cell lines.
Ecology and morphology of the Kalahari tent tortoise, Psammobates oculifer, in a semi-arid environment
(University of the Western Cape, 2012) Keswick, Tobias; Hofmeyr, Margaretha D.; Faculty of Science
Southern Africa harbours one-third of the world's Testudinid species, many of which inhabit arid or semi-arid areas, but ecological information on these species is scant. I studied the habitat, morphology and ecology of Kalahari tent tortoises over 13 months in semi-arid Savanna at Benfontein farm, Northern Cape Province, South Africa. In order to allow continuous monitoring of individuals, I attached radiotransmitters to males and females, split equally between two habitats, sites E (east) and W (west), with apparent differences in vegetation structure. Results of the study were based on data obtained from 27 telemetered tortoises and 161 individuals encountered opportunistically. Female Kalahari tent tortoises were larger than males and the sex ratio did not differ from 1:1. Based on person-hours to capture tortoises, the population appeared to have a low density, with more time required to capture a juvenile (35 hours) than an adult (10-11 hours). The frequency distribution of body size ranges was indicative of recruitment. Relative age, based on annuli counts, suggested that males were younger than females, perhaps because males as the smaller sex are more predation-prone than females. Linear relationships between annuli counts and shell volume indicated that, after reaching sexual maturity, female body size increased faster in volume than did male body size, possibly because a larger volume may enhance female reproductive success. Body condition differed between sites, sexes and among seasons. The hot and dry summer may account for low summer body condition, whereas vegetation differences and size effects, respectively, may account for the low body condition of tortoises in site W and in males. Site E was sandy with grasses, particularly Schmidtia pappophoroides, being the prevalent growth form. This habitat resembled a Savanna vegetation type Schmidtia pappophoroides – Acacia erioloba described for a neighbouring reserve. Site W was stonier, dominated by shrubs, and was reminiscent of Northern Upper Karoo vegetation (NKu3). Neither site resembled Kimberley Thornveld (SVk4), the designated vegetation type of the area. Differences in substrate and grazing intensity may have contributed to site vegetation differences. Rainfall had an important influence on seasonal vegetation. Short grass abundance correlated with rainfall and annual plants sprouted after spring rain. Refuge use changed according to season and sex. Males selected denser refuges than females did, perhaps because males were smaller and more vulnerable to predation and solar heat. Tortoises selected sparse, short grass as refuges in cool months, probably to maximise basking whilst remaining in protective cover. During hot periods, mammal burrows were preferred to vegetation as refugia. The smaller males spent more time in cover than females, which may be related to predator avoidance or thermoregulation. Females spent more time basking than males, perhaps due to their larger size and to facilitate reproductive processes. Tortoises did not brumate, but through a combination of basking, and orientation relative to the sun in their refuges, managed to attain body temperatures that allowed small bouts of activity. Body temperature for active tortoises was similar among seasons, and was higher for more specialised active behaviours, such as feeding and socialising, than for walking. Increased activity by males in spring could relate to mating behaviour while females were more active in autumn, when they foraged more than males, perhaps due to the high cost of seasonal reproductive requirements. Males displaced further per day than did females, but home range estimates did not differ between sexes. Annual home range estimates varied substantially among individuals: 0.7–306 ha for minimum convex polygons and 0.7–181 ha for 95% fixed kernel estimates. The ability to cover large areas would assist tortoises in finding resources, e.g., food, in an area where resource distribution may be patchy. Differences among seasonal home ranges and movements probably reflect seasonal climatic change; activity areas shrinking when temperatures were extreme. In order to assess the effects of a semi-arid environment on the morphology of P. oculifer, I compared its morphology to that of its ‘cool-adapted’ sister taxon Psammobates geometricus, using live and museum specimens. Both P. oculifer and P. geometricus are sexually dimorphic and differences between the two species could indicate environmental or sexual selection effects, or a combination of the two. The shorter bridge length, which allowed more leg space, and wider front feet in P. oculifer cohorts probably represent traits for manoeuvring in a sandy habitat, while wider heads in P. oculifer possibly relate to interspecific differences in diet. The flatter shell in female P. oculifer, relative to P. geometricus, may represent a trade-off between space for reproductive structures, e.g., eggs, and the need to fit into small refuges, e.g., mammal burrows. Male P. oculifer had wider shells, more space around their hind legs, and wider hind feet than P. geometricus males had, all characteristics which may assist males to fight and mate in a sandy environment.
Studies on the ecology and taxonomy of nematodes of Saldanha Bay, South Africa
(University of the Western Cape, 2013) Hendricks, Martin Gustav John; Gibbons, Mark.J
Few studies of shallow water marine nematodes have been conducted around South Africa, and none from the west coast. Here, I analyse the composition of nematode communities from six stations along a 3 km transect in Saldanha Bay during both summer and winter, in order to describe the communities present and to explore the effects of sediment composition and heavy and trace metal concentrations on community structure. In order to put the local data into a global context, these data are analysed together with some consolidated data from elsewhere and patterns of richness and composition (at the level of genus and species) examined The transect in Saldanha Bay extended from below a mussel raft at one end into the bay, and six cores (35.7mm diameter) were collected at each station. All nematodes were counted and 100 randomly identified from each core. A total of 136 nominal species, 117 genera and 36 families were identified from both summer and winter stations. Nematode abundance was highest at stations under the mussel raft, which were characterized by high mud content and high concentrations of trace and heavy metals: diversity was comparatively low and the assemblage was dominated by a few, non-selective deposit feeders (especially Sabatieria). Abundance decreased, but diversity increased, with an increase in distance from the mussel raft, which was coupled with an increase in the particle size of sediments and a significant reduction in metal concentrations. There were three dominant (Comesomatidae, Desmodoridae and Linhomoeidae, present in 96%, 85% and 83% of samples, respectively) and four subdominant families (Chromadoridae, Microlaimidae and Xyalidae, all in 79% of samples) that were largely responsible for determining the community structure across the bay. Multivariate analysis of the data using PRIMER indicated that copper was the single variable that best accounted for the structure of the communities (70.1%), and the best 2-variable combinations were copper and organic nitrogen (70.3%), followed by copper, organic nitrogen and mean grain size (69.7%). Abundance was higher at all stations in winter than summer, and the results of the PERMANOVA test on station and season indicated that the variation in between Station- Season accounted for 27% of the differences in community structure. Although these results should be treated with caution owing to limited temporal sampling, they are similar to those obtained elsewhere in the world and indicate that nematodes can be used to study anthropogenic impacts in a local context. Despite the fact that Saldanha Bay has been subjected to industrial activities for more than thirty years, estimates of species richness for Saldanha Bay were surprisingly high: S= 136; ICE = 150; CFE= 173. As too were estimates of generic richness (S= 117; ICE = 131; CFE= 149), which were the fourth most rich of those global sites compared from similar depths. Incorporation of these data into a global dataset revealed an absence of any clear latitudinal pattern in the distribution of richness (genera or families), and there was no obvious geographic structure to global communities, based on the available data. These results suggest that genera and families are poor proxies for species (at the evolutionary level, but not at the ecological level) and they support the idea that everything is everywhere. Comments on ways that nematode research can be advanced in South Africa are made.
Assisted flocculation of Chlorella Sorokiniana by co-culture with filamentous fungi
(University of the Western Cape, 2015) Mackay, Stephen; Bauer, R.
Biofuel production from microalgae is currently not economically competitive with fossil fuels due to high operational costs. A sustainable system needs to be developed which considers cultivation, harvesting and conversion to fuels as a single loop. The harvesting step has been identified as a major bottleneck within the biofuel production process, contributing to a significant proportion of the operational cost (20-30%). Chemical flocculation is a more affordable alternative to centrifugation and filtration. Chemical flocculants however negatively impact the quality of biomass and conversion efficiency to biofuel by increasing biomass ash content. Bioflocculation with biopolymers or microbes have a minimal impact on the quality of biomass. In this study, the interaction between the filamentous fungus Isaria fumosorosea and the microalgae C. sorokiniana is investigated. Under strict autotrophic conditions at pH 7-8, co-culture of microalgae (2-20 μm) with fungal blastospores resulted in theidevelopment of large pellets (1-2 mm) which may be easily harvested by sedimentation or filtration at 95% harvesting efficiency. Fungal assisted bioflocculation was compared to other harvesting methods with respect to cost and impact on the hydrothermal conversion process. Low cost carbon sources, including waste hydrothermal nutrients, minimal sugar concentrations and algal exudate may reduce fungal cultivation costs. Waste products, such as organic carbon, N, P, CO₂ and trace metals can be recycled and used for algae and fungal cultivation, closing the loop to make the system sustainable.
Systematics of the non-geniculate coralline red algae from the South African south coast
(University of the Western Cape, 2015) Van der Merwe, Elizabeth; Maneveldt, Gavin W.; Channing, Alan
The aim of this study was to document the intertidal and shallow subtidal species of non-geniculate coralline red algae from the South Africa south coast. The main emphasis of the study are encompassed in four research chapters and one concluding chapter focusing on: 1) the documentation of the non-geniculate coralline red algae occurring along the South Africa south coast; 2) revisiting the Leptophytum-Phymatolithon complex in order to resolve the taxonomic status of species previously ascribed to the genus Leptophytum from South African; 3) starting to prepare modern monographic accounts of the higher taxa; and 4) the production of updated keys to all the currently recognised taxa of non-geniculate coralline algae for South Africa. Although nowhere near complete, here we present our findings and report on the current biodiversity status of the non-geniculate coralline red algae after a further four years of extensive sampling.
Systematics, diversification and ecology of the Conophytum-clade (Ruschieae; Aizoaceae)
(University of the Western Cape, 2016) Powell, Robyn Faye; Boatwright, James S.; Magee, A. R.; Klak, C.
The Ruschieae is the most diverse and speciose tribe within the large subfamily Ruschioideae (Aizoaceae), with approximately 71 genera and a distribution centred in the arid parts of the Greater Cape Floristic Region (GCFR) of South Africa. Recent phylogenetic analyses provided the first insights into generic relationships within the tribe, with a number of novel generic relationships discovered. The tribal phylogeny recovered 12 large clades, of which the Conophytum-clade was one the most morphologically diverse based on leaf and capsule characters. The Conophytum-clade is an early-diverging lineage of the Ruschieae and includes the following 10 genera: Cheiridopsis N.E.Br., Conophytum N.E.Br., Enarganthe N.E.Br., Ihlenfeldtia H.E.K.Hartmann, Jensenobotrya A.G.J.Herre, Namaquanthus L.Bolus, Octopoma N.E.Br., Odontophorus N.E.Br., Ruschianthus L.Bolus and Schlechteranthus Schwantes. The present study presents an expanded phylogenetic analysis of the Conophytum-clade, with the sampling of the majority of species in the genera and a representative sampling (56% of species) of the speciose genus Conophytum. Phylogenetic data for up to nine plastid gene regions (atpB–rbcL, matK, psbJ–petA, rpl16, rps16, trnD– trnT, trnL–F, trnQᶷᶷᶢ–rps16, trnS–trnG) were produced for each of the sampled species. The produced plastid data was analyses using maximum parsimony, maximum likelihood and Bayesian inference. The combined plastid phylogenetic analyses were used in combination with morphological, anatomical and palynological data to assess generic and subgeneric circumscriptions within the clade. Upon assessment of generic circumscriptions in the Conophytum-clade, the number of recognised genera in the clade decreased from ten to seven. Arenifera A.G.J.Herre, which had not been sampled in any phylogeny of the Ruschieae, and Octopoma were recovered as polyphyletic, with species placed in the Conophytum-clade, while the type species was placed in the xeromorphic clade of the tribal phylogeny. The species of Arenifera and Octopoma placed in the Conophytum-clade were subsequently included in Schlechteranthus upon assessment of generic circumscriptions between the taxa. Two morphological groupings were recognised within Schlechteranthus, one including the species of Schlechteranthus and the other including species previously recognised as Arenifera and Octopoma. These two morphological groupings were treated as subgenera, with the erection of the new subgenus Microphyllus R.F.Powell. A detailed taxonomic revision of subgenus Microphyllus is presented with a key to species, descriptions of the species (including a new species: S. parvus R.F.Powell & Klak), known geographical distributions and illustrations of the species. In addition to the changes mentioned above, the expanded sampling and phylogenetic analyses of the Conophytum-clade recovered Ihlenfeldtia and Odontophorus embedded in Cheiridopsis. The species of Ihlenfeldtia were recovered with species of heiridopsis subgenus Aequifoliae H.E.K.Hartmann, while the species of Odontophorus were recovered as polyphyletic within the Cheiridopsis subgenus Odontophoroides H.E.K.Hartmann clade. Cheiridopsis was subsequently expanded to include the species of Ihlenfeldtia and Odontophorus, with these species accommodated in the subgenera of Cheiridopsis. The phylogenetic placement and relationship of these species was supported by the shared capsule morphology. The expanded sampling of the clade did not resolve the phylogenetic relationship of the monotypic genera Enarganthe, Jensenobotrya, Namaquanthus and Ruschianthus, with these genera unresolved in the Conophytum-clade. These genera however, exhibit a unique combination of morphological characters, such as a glabrous leaf epidermis and variation in pollen exine and colpi structure, in contrast to the other genera of the clade. The assessment of the generic circumscription of these genera, based on the molecular, morphological, anatomical and palynological data suggested that the generic statuses of these monotypic genera should be maintained. The expanded phylogenetic sampling of the morphologically diverse and speciose genus Conophytum recovered the genus as monophyletic. This monophyly was supported by the unique floral type in Conophytum, with the fused petaloid staminodes forming a tube. None of the sectional classifications were recovered as monophyletic but the phylogenetic analyses did recover a few clades which more or less corresponded to the current sectional classification of the genus. A number of clades were also recovered which included species from a range of different sections. Diverse leaf and floral traits were shown to have evolved numerous times across the genus. This was particularly interesting with regards to the selected floral traits, as the phylogeny indicated a number of switches in floral morphologies across the genus. The floral diversity was assessed in complex species communities of Conophytum across the GCFR, where up to 11 species of Conophytum are found occurring sympatrically, and floral traits were shown to be different across the species within the communities. Pollination competition and adaptation were suggested as possible drivers of floral diversity in the genus, with differences in phenology, anthesis and floral morphology within the species complex communities. The unique floral type of Conophytum has enabled the species to develop a diverse range of specialised flowers, with a variety of structures, scents and colours, resulting in the diverse floral morphologies found across the genus. The complex Conophytum species communities included both closely as well as distantly related species, suggesting the soft papery capsules of Conophytum are wind dispersed. This adaptation to long distance seed dispersal resulted in a significantly higher phylogenetic diversity in Conophytum when compared to its sister genus, Cheiridopsis. A population genetics study of Conophytum also suggested that the capsules may be wind dispersed, with an indication of genetic connectivity between the geographically isolated populations of C. marginatum Lavis across the Bushmanland Inselberg Region. Although the capsules are dispersed by wind, the seeds are released from the hygrochastic capsules by runoff during rainfall events. The relationship between seed dispersal and runoff is evident from the genetic structure of populations of C. maughanii N.E.Br. and C. ratum S.A.Hammer that occur on the tops and the surrounding bases of the inselbergs, as the drainage pattern was found to directly influence population structure in these species. In addition, the AFLP analyses provided insight into the conservation of the flagship species C. ratum. The summit populations of this species were shown to sustain the populations at the base of the Gamsberg. This finding is especially important, as the distribution of the species is restricted to the Gamsberg inselberg, where mining has already commenced as of this year.

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