Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320190003&lang=pt vol. 115 num. 5-6 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Reflecting on the nature of knowledge</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300001&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>CSIR launches novel online climate risk profiling and adaptation tool: The Green Book</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300002&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>South Africa's Copyright Amendment Bill: Implications for universities</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300003&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>A new era for marine forecasting in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300004&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Programme for the development of weather and climate numerical modelling systems in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300005&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Learning to doubt and challenge everything related to Eskom and other parastatals in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300006&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Tracing the origins of South African constitutionalism</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300007&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Quantifying a sponge: The additional water in restored thicket</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300008&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Building assessment practice and lessons from the scientific assessment on livestock predation in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300009&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Progress towards obtaining valid vaccination coverage data in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300010&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Colourful chemistry of South African latrunculid sponges</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300011&lng=pt&nrm=iso&tlng=pt Marine sponges - in common with many other sessile marine invertebrates seemingly devoid of obvious physical forms of defence against predators, e.g. spines or shells - are the sources of a diverse array of organic chemical compounds known as marine natural products or secondary metabolites. Recent research has indicated that the production of natural products via cellular secondary metabolic pathways in some sponge species may not occur within the sponge cells themselves, but rather in microbial endosymbionts which inhabit the surface and interstitial spaces within the sponge tissue. Regardless of their biosynthetic origin, the bioactivity, e.g. toxicity, of many of these marine natural products may be utilised by sponges as chemical feeding deterrents to discourage predation or to provide a chemical anti-fouling competitive edge in the intense competition for living space amongst filter-feeders on space-limited benthic reefs. Paradoxically, a small number of sponge natural products have serendipitously shown potential as new pharmaceuticals, e.g. novel anti-cancer drugs. Marine biodiscovery (or bioprospecting) is the search for new pharmaceuticals from marine organisms. Exploration of the taxonomy, natural products chemistry and biomedicinal potential of the rich diversity of South African latrunculid sponges (family Latrunculiidae), at Rhodes University, the South African Department of Environmental Affairs and the University of the Western Cape has continued unabated for over a quarter of a century as part of a collaborative marine biodiscovery programme. A short review of this multidisciplinary latrunculid sponge research is presented here. SIGNIFICANCE: • Research into the taxonomy, chemistry and microbiology of latrunculid sponges is the most comprehensive, multidisciplinary investigation of any group of African marine sponges. • The potent cytotoxicity of the pyrroloiminoquinone alkaloid pigments isolated from latrunculid sponges may have biomedical applications. • This review underlines the importance of conserving and protecting South Africa's unique marine invertebrate resources. <![CDATA[<b>Plagiarism in South African management journals: A follow-up study</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300012&lng=pt&nrm=iso&tlng=pt Internationally, a rise in plagiarism by academics has been reported. The objective of the present study was to examine the extent of plagiarism in articles appearing in 19 South African management journals published in 2016 and to compare the findings to a study undertaken in 2015 using 2011 data from the same 19 journals. This study progresses the debate around academic ethics and academic integrity in the country - a topic, thus far, that has received little research attention. A total of 454 published articles were submitted through the similarity detection software Turnitin™. High and excessive similarity was identified and over 80% of submissions evidenced similarity in excess of 9%. University administrators, journal editors and publishers, and the South African Department of Higher Education and Training are alerted to this plagiarism that undermines the academic pursuit. This awareness is particularly important as faculty serve as role models to students. Measures should thus be taken to ensure that faculty provide sound role models as ethical researchers. SIGNIFICANCE: • Plagiarism is an ongoing and increasing problem and is particularly concerning when faculty themselves plagiarise, as it impacts institutional integrity and culture, and negatively influences role modelling for students. • The present study highlights the increase in plagiarism in the field of management and alerts other fields of academia to this problem. • University administrators and journal editors and publishers are reminded about the roles they can play to address plagiarism. <![CDATA[<b>Nurdle drifters around South Africa as indicators of ocean structures and dispersion</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300013&lng=pt&nrm=iso&tlng=pt Dispersion processes in the ocean typically involve wind, ocean currents and waves. All these factors were included in an analysis to model nurdle dispersion from an accidental spill in Durban Harbour, South Africa, in October 2017. Nurdle sightings on beaches by members of the public are used as indicators of the dispersion which extended over 2000 km of the South African coastline in a period of 8 weeks. Using known oceanographic current structures, satellite imagery, wave data and surface wind drift values of between 5% and 8% of wind speed, good agreement was found between the modelled dispersion and nurdle sightings. In particular, it was found that nurdles remained in specific sections of the coast for long periods, and that sporadic wind events were required to move them into new coastal areas. Such results may also contribute to understanding the dispersal behaviours and strategies adopted by larval stages of marine organisms, particularly fishes, that have pelagic larval durations that extend over weeks to months. The event was recognised as a major pollution incident rivalling other nurdle spillages reported worldwide, and extensive efforts were made to collect the nurdles, particularly along the northern KwaZulu-Natal coast. However, 9 months later, less than 20% had been recovered. The results emphasise the connectivity of different ocean regions, and in particular that pollution of the ocean is not a localised activity. Matter discharged at one point will disperse over a wide area - in this case, significantly further afield than the area of recovery operations. SIGNIFICANCE: • Wind drift in the upper metre or two of the ocean has been notoriously difficult to quantify, and the spread of nurdles along the South African coastline can only be explained by using drift percentages two or three times the generally accepted value of 3% or less. Nonetheless, it is important to realise that there are substantial differences in dispersion rates between the upper few centimetres of the ocean and that even a metre or two deeper. • The rapid manner in which nurdles, and other microplastics, can be dispersed is important in terms of understanding the spread of this form of pollution in the world's oceans. The results also confirm the important role that wind can play in the movement of eggs, larvae and invertebrates and the significance of vertical migrations in and out of the surface layers. • Finally, the results confirm many of the accepted coastal current regimes on the east and south coasts of South Africa. Moreover, it is shown that certain sections can have very long residence times, where drifters are only removed under sustained wind conditions. <![CDATA[<b>Historical and projected trends in near-surface temperature indices for 22 locations in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300014&lng=pt&nrm=iso&tlng=pt Motivated by the risks posed by global warming, historical trends and future projections of near-surface temperature in South Africa have been investigated in a number of previous studies. These studies included the assessment of trends in average temperatures as well as extremes. In this study, historical trends in near-surface minimum and maximum temperatures as well as extreme temperature indices in South Africa were critically investigated by comparing quality-controlled station observations with downscaled model projections. Because climate models are the only means of generating future global warming projections, this critical point comparison between observed and downscaled model simulated time series can provide valuable information regarding the interpretation of model-generated projections. Over the historical 1951-2005 period, both observed data and downscaled model projections were compared at 22 point locations in South Africa. An analysis of model projection trends was conducted over the period 2006-2095. The results from the historical analysis show that model outputs tend to simulate the historical trends well for annual means of daily maximum and minimum temperatures. However, noteworthy discrepancies exist in the assessment of temperature extremes. While both the historical model simulations and observations show a general warming trend in the extreme indices, the observational data show appreciably more spatial and temporal variability. On the other hand, model projections for the period 2006-2095 show that for the medium-to-low concentration Representative Concentration Pathway (RCP) 4.5, the projected decrease in cold nights is not as strong as is the case for the historically observed trends. However, the upward trends in warm nights for both the RCP4.5 and the high concentration RCP8.5 pathways are noticeably stronger than the historically observed trends. For cool days, future projections are comparable to the historically observed trends, but for hot days noticeably higher. Decreases in cold spells and increases in warm spells are expected to continue in future, with relatively strong positive trends on a regional basis. It is shown that projected trends are not expected to be constant into the future, in particular trends generated from the RCP8.5 pathway that show a strong increase in warming towards the end of the projection period. SIGNIFICANCE: • Comparison between the observed and simulated trends emphasises the necessity to assess the reliability of the output of climate models which have a bearing on the credibility of projections. • The limitation of the models to adequately simulate the climate extremes, renders the projections conservative, which is an important result in the light of climate change adaptation. <![CDATA[<b>The meaning and practice of stewardship in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300015&lng=pt&nrm=iso&tlng=pt Stewardship offers a means of addressing social-ecological sustainability challenges, from the local to the global level. The concept of stewardship has had various meanings attached to it over time, and the links between the theory and practice of stewardship are not well understood. We sought to characterise the practice of stewardship in South Africa, to better understand the relationship between theory and practice. We found that practitioners' understandings of stewardship coalesce around two core notions: the idea of stewardship as 'responsible use and care' of nature, and stewardship as a 'balancing act' between stewards' use of natural resources for agricultural production and their responsibility to protect and manage the wider ecosystem. Stewardship practice in South Africa is strongly influenced by the biodiversity stewardship tool; however, many practitioners are integrating biodiversity stewardship with other approaches. These emerging social-ecological stewardship initiatives operate at landscape-level and work towards integrated social and ecological stewardship outcomes, by facilitating collaboration among diverse stakeholders. Further research is needed to better understand what is required to support these integrated, collaborative and cross-sectoral initiatives. Policy mechanisms that facilitate integrated place-based stewardship practice can contribute to expanding the practice of biodiversity stewardship in South Africa. SIGNIFICANCE: • Our findings contribute to a growing understanding of what stewardship looks like in South Africa and how it is put into practice. • We show that biodiversity stewardship is a prevalent understanding of stewardship practice in South Africa and is often combined with other approaches for sustainable landscape management. • A broader understanding of stewardship, for example through the concept of social-ecological stewardship, can enable more integrated, collaborative approaches to landscape management, addressing the wide range of environmental and social development challenges faced in rural landscapes across South Africa. <![CDATA[<b>Anthropogenic disturbances of natural ecohydrological processes in the Matlabas mountain mire, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300016&lng=pt&nrm=iso&tlng=pt Matlabas is a mountain mire in Marakele National Park, located within the headwaters of the Limpopo River in South Africa. This mire consists of a complex of valley-bottom and seepage wetlands with small elevated peat domes. The occurrence of one decaying peat dome, which has burnt, and desiccated wetland areas with terrestrial vegetation has raised concerns. The aim of this study was to understand the mire features and water flows in order to identify the potential drivers causing wetland degradation. Wells and piezometers were installed to monitor the hydraulic head and collect water samples for analysis of ion composition, 18O and ²H stable isotope content, and δ13C and 14C isotope content for radiocarbon dating. Moreover, peat temperature profiles were measured and peat deposits were also dated using radiocarbon. Results indicate that the Matlabas mire developed in the lowest central-east side of the valley by paludification at the onset of the Holocene. During the Mid-Holocene, peat development was extended laterally by autogenic and allogenic processes. Three types of water flows driving peat development were identified - sheet flow, phreatic groundwater flow and deep groundwater flow - two of which are surface or near surface flows. The recent occurrence of decaying peat domes and desiccated wetland areas is possibly related to loss of exfiltrating deep groundwater flows that have resulted from drainage by the head-cut channels in the mire and interception of near surface water flow by an access road, respectively. Interventions should be undertaken to prevent further degradation of the mire. SIGNIFICANCE: •This study is the first, as far as we are aware, on the ecohydrology of an inland mountainous mire in southern Africa. •The results highlight the importance of the current wetland management (including rehabilitation) initiatives in South Africa. •The integrative ecohydrological methods can be applied in other headwater wetlands in southern Africa. <![CDATA[<b>The ecosystem of e-learning model for higher education</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300017&lng=pt&nrm=iso&tlng=pt We present the ecosystem of e-learning (EeL) model, which can be applied to any higher education context, and which takes full account of all inhabitants and their interrelationships, not only the components, of the e-learning food chain. Specifically, this model was applied to our context within the University of the Western Cape, highlighting the role of the academic developer within the model. A key argument advanced in this paper is that academic developers should work to reduce complexities associated with emerging e-tools. The EeL model is used to emphasise the role of academic developers as mediators between components and relationships. SIGNIFICANCE: • By the application of the EeL model, it is demonstrated that the use of e-tools and their alignment with pedagogies within any context must be sensitive to the entire ecosystem, with the recognition that this is simultaneously a top-down and a bottom-up process. • The student must be the core focus in the adoption of emerging technologies and the learning process, but simultaneously the student can only be in focus when they are placed within their broader ecosystem - including the societal level. • Our findings add to the debate on physics education specifically, and more broadly by providing new ways of conceptualising an e-learning ecosystem. • It is advocated that an academic developer-mediator should step in to mediate between academics, tutors and emerging e-tools, through a structured developmental process for learning and teaching. • The EeL model can afford an insight into the processes involved when incorporating a learning management system (and emerging e-tools) into learning and teaching in higher education institutions. <![CDATA[<b>Metatarsophalangeal proportions of <i>Homo naledi</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300018&lng=pt&nrm=iso&tlng=pt Post-cranial differences between extant apes and humans include differences in the length, shape and size of bone elements relative to each other; i.e. differences in proportions. Foot proportions are influenced by the different functional requirements of climbing and bipedal locomotion. Phalangeal length is generally correlated with locomotor behaviour in primates and there is variation in hominins in relative phalangeal lengths - the functional and evolutionary significance of which is unclear and currently debated. Homo naledi has a largely modern rearfoot (i.e. tarsal skeleton) and midfoot (i.e. metatarsal skeleton). The proximal pedal phalanges of H. naledi are curved, but the relative lengths are unknown, because the phalanges cannot reliably be associated with metatarsals, or in many cases even with ray number. Here, we assess the lengths of the proximal pedal phalanges relative to the metatarsals in H. naledi with resampling from modern human and chimpanzee (Pan troglodytes) samples. We use a novel resampling method that employs two boundary conditions, assuming at one extreme that elements in the sample are associated, and at the other extreme that no elements are associated. The associated metatarsophalangeal proportions from digits 1 and 2 are within the 95% confidence interval of the modern human distribution. However, the associated and unassociated proportions from digits 3-5 fall above the 95% confidence interval of the human distribution, but below and outside of the chimpanzee distribution. While these results may indicate fossil preservation bias or other sample-derived statistical limitations, they potentially raise the intriguing possibility of unique medial versus lateral pedal column functional evolution in H. naledi. Additionally, the relevant associated proportions of H. naledi are compared to and are different from those of H. floresiensis. Both species suggest deep phylogenetic placement so the ancestral condition of the pedal phalanges in the genus Homo remains unclear. SIGNIFICANCE: • Modern humans demonstrate straight and relatively short pedal phalanges, whereas H. naledi demonstrates curved phalanges of an unknown relative length. This research analyses the relative length of the proximal phalanges to the metatarsals to determine if H. naledi has relatively short phalanges similar to modern humans or is distinct from modern humans in both its phalangeal length and curvature. • This analysis further develops a statistical resampling method that was previously applied to large fossil assemblages with little association between bones. • A more comprehensive understanding of pedal morphology of H. naledi could provide insight into the ancestral pedal form of the genus Homo as the overall morphology of H. naledi appears to be deeply rooted in the genus. <![CDATA[<b>Developmental stress in South African hominins: Comparison of recurrent enamel hypoplasias in <i>Australopithecus africanus</i> and <i>Homo naledi</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300019&lng=pt&nrm=iso&tlng=pt Discovery of a new hominin (Homo naledi) in the same geographical area as Australopithecus africanus creates the opportunity to compare developmental dental stress in higher latitude hominins with low that in latitude apes, among whom repetitive linear enamel hypoplasia (rLEH) recurs seasonally at about 6 or 12 months. In contrast to equatorial Africa, a single rainy/dry cycle occurs annually in non-coastal southern Africa. It is predicted that LEH will recur annually but not differ in duration between ancient and more recent hominins. Data were collected from epoxy casts of anterior teeth attributed to H. naledi (18 incisors, 13 canines) and A. africanus (29 incisors, 8 canines) using a digital microscope, surface scanner and scanning electron microscope. The location, number, width, depth and distance between defects (including perikymata counts and spatial measurements) of 136 LEH events were compared among crown moieties (deciles 4-6 and 7-9), tooth types and taxa. Enamel defects are concentrated in the cervical half of anterior crowns, and in similar numbers in each taxon. Contrary to expectations, H. naledi show bimodal LEH durations reconstructed at about 2 and 8 weeks compared to just 4 weeks in A. africanus. Both taxa show bimodally recurrent episodes of LEH centring on 2 and, more commonly and severely, 6 months. A combination of two independent annual stressor types, one disease and one seasonal, could explain the observations. These estimations of duration and recurrence of developmental stress require evaluation using actual perikymata periodicity for H. naledi and more refined understanding of palaeoenvironments for both taxa. SIGNIFICANCE: • Seasonal stress is a central concern in the biological and health sciences. Because of the innate way that enamel is deposited, the timing of stress in the childhood of apes, modern humans and their fossil ancestors can be measured with a precision of about 1 week. • Application of this method to South African Pliocene Australopithecus africanus and Mid-Pleistocene Homo naledi reveals that, unexpectedly, both forms show semi-annual stress - a finding that is tentatively attributed to two independent annual stressors, possibly disease and malnutrition. <![CDATA[<b>A comparison of hominin teeth from Lincoln Cave, Sterkfontein L/63, and the Dinaledi Chamber, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000300020&lng=pt&nrm=iso&tlng=pt Prior to the recovery of Homo naledi from the Dinaledi Chamber of the Rising Star Cave system, the Middle Pleistocene fossil record in Africa was particularly sparse. With the large sample size now available from Dinaledi, the opportunity exists to reassess taxonomically ambiguous teeth unearthed at the nearby site of Sterkfontein. Teeth recovered from Lincoln Cave South and area L/63 at Sterkfontein have been considered 'most probably Homo ergaster' and 'perhaps Archaic Homo sapiens', respectively. Given the similarities shared between Lincoln Cave, area L/63, and the Dinaledi Chamber with regard to climatic/geologic depositional context and age, two teeth from the former sites, StW 592 and StW 585 respectively, were compared with corresponding tooth types of H. naledi from the Dinaledi Chamber. The results of our study indicate that the Lincoln Cave and area L/63 teeth are morphologically inconsistent with the variation recognised in the H. naledi teeth. SIGNIFICANCE: • The similar age and climatic/geologic depositional and post-depositional circumstances at Lincoln Cave South, area L/63 at Sterkfontein and the Dinaledi Chamber, Rising Star raise the possibility that these fossils might represent the same species. • The teeth StW 592 and StW 585 are not consistent with the variation evident in the known H. naledi sample. • The results of the study do not add to the question of the existence of at least two species of the genus Homo living in close proximity to each other in South Africa at approximately the same time.