1834 research outputs found
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An assessment of recreational bank angling in the Free State province, South Africa, using licence sale and tournament data
No full textRecreational angling is an important form of utilisation of inland fisheries in South Africa but there is little information on this sector. The objective of this study was to provide an assessment of recreational bank angling in the Free State Province using licence sale and tournament data. During 2013 and 2014, 8 256 and 7 710 angling licences were sold, respectively. This represents a decline of 76% compared to the total licence sales in the Province in 1971. Tournament catch and effort data were obtained for 4 796 tournaments that were held on 17 dams from 1974 to 2014. Reported tournament effort decreased by 67% from 8 548 tournament days in 1998 to 2 828 days in 2014. Tournament catch composition was dominated by alien common carp Cyprinus carpio. Overall, this species comprised 81% of the weight and 77% of the number of fish landed during tournaments making it the most important angling species. The recent observed increase in subsistence angling could not be included in the analysis as participants are mostly not licensed. Alternative methods are therefore required if total catch and effort are to be estimated
Gill net catch composition and catch per unit effort in Flag Boshielo Dam, Limpopo Province, South Africa
No full textGill net surveys were conducted in 2013 to determine species composition and fisheries potential of Flag Boshielo Dam. Species contributing the most towards total biomass were Labeo rosae (40%), Oreochromis mossambicus (15%), Schilbe intermedius (10%) and Labeobarbus marequensis (9.8%). Catch per unit effort for gill nets set at night (4.4 ± 0.6 kg•100 m-net⁻¹•hr⁻¹) was significantly higher (P < 0.05) than for those set during the day (0.9 ± 0.1 kg•100 m-net⁻¹•hr⁻¹). Total fish biomass captured in 30, 50, 70, 90 and 110 mm mesh sized nets was 3.1, 31.5, 43.5, 23.5 and 16.1 kg, respectively. Catch in gillnets with mesh sizes ≥ 70 mm was dominated by L. rosae comprising 60% of the catch in the 70 mm mesh; L. rosae (40%) and O. mossambicus (36%) in the 90 mm mesh; and O. mossambicus (40%) and Clarias gariepinus (40%) in the 110 mm mesh. If a small-scale fishery were to be initiated, it is recommended that mesh sizes should exceed 70 mm and that further research on the biology and ecology of the main target species and of the current utilisation of the fishery be conducted to guide sustainable utilisation. © 2017, South African Water Research Commission. All rights reserved
Register of grants, 2016/17
No full textThe NRF Register of Grants provides information to all NRF stakeholders on the grants that have been awarded in the financial year 2016/2017 to researchers by the NRF’s Research and Innovation Support Advancement Directorate (RISA).National Research Foundation (South Africa
Response of Crested Guinea-fowl (Guttera edouardi), a forest specialist, to spatial variation in land use in iSimangaliso Wetland Park, South Africa
No full textGlobally anthropogenic pressures on natural environments have caused species decline. Ground dwelling bird species declined in numbers because of loss of habitat and nesting sites. Protected areas (PAs) are generally perceived as areas with little disturbance; however, many have/are also subjected to anthropogenic land use change, such as agroforestry. Consequently, we investigated the presence and habitat use of a terrestrial avian species, the Crested Guinea-fowl (Guttera edouardi), in iSimangaliso Wetland Park, South Africa, a PA with varying land use change. We used single-season camera trap data from 99 trap stations across 24 days, and single season occupancy models to quantify the influence of habitat conversion and habitat characteristics on occupancy and detection probability of Crested Guinea-fowl. The average site occupancy (±standard error) and detection probability (±standard error) under the variable influence was 0.40 ± 0.07 and 0.43 ± 0.06 respectively from the top models. The most influential variables were natural forests, shrub cover, leaf litter, weed dominance, distance to water and narrow path. The natural forests, weed dominance and shrub cover positively influenced the occupancy of Crested Guinea-fowl. Leaf litter and distance to water had a positive influence on detection probability while narrow path had a negative influence. Our findings highlight the importance of natural forests to the survival of Crested Guinea-fowl in landscapes modified for agroforestry. Management initiatives are mandatory to ensure protection of adequate natural habitat for the conservation of forest specialists.National Research Foundation (South Africa
Observations of microtrash ingestion in Cape Vultures in the Eastern Cape, South Africa.
No full textIngestion of man-made items by birds can reduce stomach volume and block the digestive track. In southern Africa, microtrash within the regurgitation of Cape Vulture nestlings was last documented in 1983. We present evidence of nestling microtrash ingestion after a 30-year gap. Vulture nestlings were captured at a breeding colony in the Eastern Cape, South Africa. One nestling regurgitated three microtrash fragments. Two pieces of microtrash were collected from the nest of another nestling. Neither nestling appeared to have skeletal deformities or feather stress bars. Our results highlight the persistence of microtrash ingestion by Cape Vulture nestlings, which could impact the species negatively.National Research Foundation (South Africa
Three years comparative media coverage for DST-NRF-SAASTA and facilities (2014/2015, 2015/2016, 2016/2017)
No full textThe report covers the media articles from 2014/2015 to 2016/2017 that were able to be detected by the tracking system for DST, NRF, SAASTA and the facilities. It should be noted that the system does not cover all of the media especially the community media. Some of the media articles might have been missed during the tracking as a result the report focuses on those articles that were able to be tracked. This report does not cover social media report. The following was covered in the report; media coverage, AVE, language covered, provincial coverage, the regional and international coverage and the type of media. The data collected reflect the raw count in each case
Closed doors: gendered power relations and the use of mature themes in eurocentric fairytales
No full textEstablished critics, such as Jack Zipes, assert that the subject matter of fairytales shows evidence that the Westernised 'classics' (by authors such as Charles Perrault or the Grimm brothers) were influenced by the cultural norms of their contemporary society and served as a pedagogical tool for mass socialisation. Often authors writing for younger audiences deliberately inserted a moralising function into these tales, in order to normalise and further disseminate certain gender ideals. Their presentation of adult or mature themes (such as sexuality) is often problematic, with some references presented quite naturally and others excluded entirely. This paper investigates modern retellings of Eurocentric fairytales, and speculates on the significance of the perpetuation or complete elision of such themes, and what their selective invocation might intimate about the culture in which the story is produced. It argues that the way in which the fairytale narrative engages with mature themes is demonstrative of its contemporary ethos and its associated cultural bias, which is conveyed unconsciously through the vehicle of the text. Through a critical analysis of relevant literature, the paper explores the maintenance of socio-cultural norms in fairytales as being emblematic in their establishment as cultural relics.National Research Foundatio
The application of kinematics to reproduce patellar cartilage and determine the compression thereof during specific movements
No full textThe aim of this study is to investigate the biomechanics of the patellofemoral joint
in an in-vitro model. The project has three objectives: Firstly, a process needs to be
designed that is able to estimate the geometry of the patellofemoral joint cartilage.
Secondly, cartilage compression as a result of the investigated movements are
determined. Finally, the associated stresses are estimated. The outcome of the
objectives will provide information on the degree of cartilage deformation during
different functional tasks.
The geometry of the patellar cartilage was estimated through the use of kinematics,
the bones from the CT scans of the patella and femur, and the MRI scans of the
uncompressed patellofemoral cartilage. This process included reproducing the
kinematic models of two knees for a passive and squat motion and then using the
results to estimate the patellar cartilage. It was found that the process was able to
estimate the geometry of the patellar cartilage through the application of the
kinematics and the uncompressed cartilage produced by the MRI scans. It was noted
that the cartilage geometry differed between motions and between investigated
knees in terms of thickness, but in general conformed to the geometry of patellar
cartilage.
The deformation and compression of the patellofemoral cartilage was also
determined by comparing the resulting estimated cartilage with the uncompressed
cartilage segmented from the MRI scans. The main finding was that compression
of the cartilage does result from the application of the investigated movements and
that there was a definitive difference between the passive and squat movements.
Finally, the stresses as a result of the different compressions on the cartilage were
investigated through FEA. The main findings was that the squat movement
consistently resulted in larger stresses than the passive movement and that the
stresses recorded on the patellar osseous-cartilage surface interface also produced
larger stresses than the stresses found on the cartilage surface.
It was concluded that the designed process was able to determine the geometry of
the patellar cartilage by using kinematics and the CT scans of the knee with little
input from the MRI scans. Furthermore, through using kinematics, the compression
of the cartilage due to these movements could be determined. It was concluded that
the squat movement consistently produced larger compressions and stresses than
the passive movement. This leads to the conclusion that it would be more
appropriate to use the passive compression to modify and improve patellar
replacements since it results in less compression and smaller stresses on the patella.
Therefore, the replacement can still be modified to improve the geometry and
account for some compression in the replacement, but not modified too much
through the use of the squat movement to cause excessively larger stresses in the
knee.National Research Foundatio
Comparative genomics of Knoxdaviesia species in the core Cape subregion
No full textKnoxdaviesia capensis and K. proteae are saprotrophic fungi that inhabit the seed cones
(infructescences) of Protea plants in the Core Cape Subregion (CCR) of South Africa.
Arthropods, implicated in the pollination of Protea species, disperse these native fungi from
infructescences to young flower heads (inflorescences). Knoxdaviesia proteae is a specialist
restricted to one Protea species, while the generalist K. capensis occupies a range of Protea
species. Within young flower heads, Knoxdaviesia species grow vegetatively, but switch to
sexual reproduction once flower heads mature into enclosed infructescences. Nectar becomes
depleted and infructescences are colonised by numerous other organisms, including the
arthropod vectors of the fungi.
The aim of this dissertation was to study the ecology of K. capensis and K. proteae by
making use of their genome sequences. Knoxdaviesia belongs to the family
Gondwanamycetaceae, for which no genomes were available at the start of this study. Using
Illumina technology, we determined the genome sequences of both CCR Knoxdaviesia
species and applied them to investigate reproduction, substrate use and tolerance to
competition.
Population genetic studies on K. capensis and K. proteae have revealed massive diversity,
suggesting an outcrossing reproductive strategy. To determine the genetic basis for this
diversity, we used the genomes to identify and characterise their mating type (MAT) loci.
Each species contained only a single MAT idiomorph per isolate, indicating that they require
an individual of the opposite mating type for sexual reproduction. The MAT loci of the two
Knoxdaviesia species were almost identical, reflecting their phylogenetic relatedness. The
features of the Knoxdaviesia MAT1-2-7 gene also suggested a historic recombination event
between the MAT1-1 and MAT1-2 idiomorphs.
The carbon resources that Knoxdaviesia species utilise were investigated with phenome
assays and compared to the carbon usage profile of a Protea pathogen, Ceratocystis
albifundus. Knoxdaviesia capensis, the generalist, utilised the widest range of substrates,
whereas the pathogen utilised the least. The Knoxdaviesia species were able to grow on all
monosaccharides that occur in Protea nectar. The predicted proteins in the Knoxdaviesia and
C. albifundus genomes suggested that cell wall degradation is important to the nutrition of
Knoxdaviesia species in infructescences, whereas the pathogen prefers plant storage polysaccharides. Overall, carbon metabolism in three ecologically different, but related fungi
reflected their ecological adaptations.
Knoxdaviesia species appear to be effective competitors in infructescences. Few secondary
metabolite biosynthesis clusters were, however, detected from the K. capensis and K. proteae
genomes. This may suggest that it is the antimicrobial products of Streptomyces bacteria that
rid infructescences of fungal competitors. The few secondary metabolite clusters of the
Knoxdaviesia species likely produce compounds that enable them to tolerate these bacteria
and arthropod and nematode predation. Proteins involved in cell defence were also detected
among the predicted secreted proteins of K. capensis and K. proteae. Knoxdaviesia proteae
appears to have some non-functional secondary metabolite clusters and secretes less cell
defence proteins than K. capensis, suggesting that its specialisation on a single host has
resulted in the loss of some functions.National Research Foundatio
Investigating the impact of MpAPr1, an aspartic protease from the yeast Metschnikowia pulcherrima, on wine properties
No full textProtein removal is a key step during the production of white wine in order to avoid the possible
appearance of a harmless but unsightly haze. Alternatives to the use of bentonite are actively
sought because of technological, organoleptic and sustainable issues associated with its use.
Acid proteases that are able to break down proteins under winemaking conditions could be one
such alternative. Recent literature reports the successful outcome of the addition of fungal
aspartic proteases from Aspergillus and Botrytis. In this study, MpAPr1, an extracellular aspartic
protease previously isolated and partially characterised from the yeast Metschnikowia
pulcherrima, was cloned and expressed heterologously in Komagataella pastoris. Enzymatic
properties of MpAPr1 were initially (Km, Vmax, K’i, optimal pH and temperature for protease
activity, impact of minerals, sugars and ethanol on protease activity) characterised in a crude
extract. After several attempts using different techniques, MpAPr1 was successfully purified via
cation exchange chromatography. Its activity against haze-forming grape proteins was initially
tested in a model solution under optimal environmental conditions (for MpAPr1 activity) and
under those occurring during winemaking (pH 3.5 and 25°C). Thereafter, MpAPr1 activity was
evaluated in grape must and throughout alcoholic fermentation. These experiments showed that
MpAPr1 was able to degrade certain haze-forming proteins, especially chitinases, under optimal
conditions and to a lesser extent under winemaking conditions. Prior denaturation of the target
proteins by heat treatment was also not required. Moreover, MpAPr1 was able to degrade yeast
proteins in a model solution under both conditions. Finally, the presence of MpAPr1,
supplemented to grape must, resulted in the partial degradation of grape proteins throughout
fermentation and ultimately in a slight difference in the wine’s volatile compound composition.
Winemaking conditions limited its impact and it is thus proposed that future work focus on
enhancing MpAPr1 activity to make it a viable alternative to bentonite. The study nevertheless
provides further evidence that aspartic proteases could represent a potential alternative to
bentonite for the wine industry and that non-Saccharomyces yeasts such as M. pulcherrima
could have a beneficial impact on wine properties.National Research Foundatio