Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320070004&lang=en vol. 103 num. 7-8 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Combined marine storm and Saros spring high tide erosion events along the KwaZulu-Natal coast in March 2007</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Sexual dimorphism in early <i>Homo</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400002&lng=en&nrm=iso&tlng=en <![CDATA[<b>Speaking truth to power in South Africa</b>: <b>nutritional influences on HIV infection and tuberculosis</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400003&lng=en&nrm=iso&tlng=en <![CDATA[<b>GM biotechnology</b>: <b>friend and foe?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400004&lng=en&nrm=iso&tlng=en <![CDATA[<b>The science in the intelligent design debate</b>: <b>teach it like it is</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400005&lng=en&nrm=iso&tlng=en <![CDATA[<b>Monitoring effects of anthropogenic climate change on ecosystems</b>: <b>a role for systematic ecological observation?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400006&lng=en&nrm=iso&tlng=en <![CDATA[<b>The diversity of culturable airborne fungi in an active South African gold mine</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400007&lng=en&nrm=iso&tlng=en Several studies have been conducted on the presence and diversity of airborne fungal spores in residential and occupational areas. This is the first investigation on this topic in the mining environment. The impact of fungi-especially as opportunistic pathogens-on their health and productivity needs to be assessed, considering the compromised health of a large number of HIV-infected miners in South Africa. Accordingly, the aim of this study was to determine the abundance of fungal spores as well as the diversity of culturable airborne fungi in an active gold mine. The results indicate that three of the sampled sites in the mine contain abundant numbers of culturable airborne fungi. The first site was next to an auxiliary extraction fan, which could act as an accumulator for airborne fungal spores from the rest of the mine. The two other sites had high human activity, disturbances from which may contribute to an elevated fungal load in the air. The presence of timber supports at one site may serve as a growth substrate for several fungal genera. The diversity of filamentous fungal genera increased from outside the mine to deeper into the mine, whereas the diversity of yeast genera followed an opposite trend, with no yeasts detected deep in the mine. Although most of the isolates identified are not pathogens, they could still have a negative impact (either as opportunistic pathogens or allergens) on workers, especially immunocompromised persons if exposed to them for prolonged periods. <![CDATA[<b>Hyper-resistance to arsenic in bacteria isolated from an antimony mine in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400008&lng=en&nrm=iso&tlng=en Soil and water sites were sampled at a South African antimony mine with elevated levels of arsenic due to the refining process. Enriched media yielded two pure bacterial cultures able to grow in both arsenite and arsenate. These were identified as Stenotrophomonas maltophilia SA Ant 15 and Serratia marcescens SA Ant 16. Stenotrophomonas maltophilia SA Ant 15 was resistant to 10 mmol l-1 arsenite and 20 mmol l-1 arsenate, whereas S. marcescens SA Ant 16 grew in 15 mmol l-1 arsenite and in up to 500 mmol l-1 arsenate, making it the most arsenic-resistant organism described to date. During growth, addition of arsenate or arsenite anions adversely affected biomass production and maximum specific growth rate and, in some instances, longer lag phases were induced. Reduction of arsenate to arsenite partly accounted for the high tolerance of the bacteria to arsenate. Our results suggest the use of these hyper-resistant bacteria as remediation agents in areas where arsenic contamination is prohibitively high. <![CDATA[<b>Frequency of stressful life events as risk indicating factors for the onset of type 1 diabetes in African children</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400009&lng=en&nrm=iso&tlng=en A total of 42 children aged 6–15 years with type 1 diabetes, and 49 control children aged 6-14 years, participated in this study. Life events during the year prior to the clinical onset of type 1 diabetes that occurred within the family were recorded on a survey consisting of 45 questions. The mean frequencies of these life events were higher in diabetic children (7.7) than in the healthy control group (4.9). Diabetic children were found to experience higher relative frequencies of stressful life events within the range of 38-48%, compared with the children of the control group (range 8-16%). The highest relative frequency of 55% for both groups was the birth or adoption of a brother or sister. Life events involving actual or threatened losses within the family, such as serious illness or death of the mother, death of brother or sister, or hospitalization of mother or father, showed significantly increased frequencies in the diabetic group (range 10-30%) than in control children (range 4-10%). We propose that these stressful life events may be factors that precipitate severe emotional stress, increasing consequent risk of later development of type 1 diabetes. <![CDATA[<b>South African Environmental Observation Network</b>: <b>vision, design and status</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400010&lng=en&nrm=iso&tlng=en The South African Environmental Observation Network (SAEON), which has its origins in the scientific community, has evolved significantly over the last five years. Core government support for this emerging initiative became a reality in 2002, when the first funding commitment was made. The establishment of an ambitious distributed national environmental observation system requires extensive partnership arrangements, ranging from participating government departments, through numerous institutions and the corporate sector, to the active individual researchers. In its first three years, SAEON has established its credentials within the South African scientific community, created and staffed a national office at the National Research Foundation, launched the first three of six envisaged distributed observation nodes, expanded its regional and international relevance, and has made great strides with an educational outreach programme. Three additional nodes are nearing completion and all should be operational by early 2008. The financial and institutional sustainability of SAEON was of paramount importance and consumed most of its energy during this establishment phase. The current three-year period (2006-2008) is devoted primarily to securing the scientific sustainability of the SAEON initiative through its nodes and associated partner networks, and to integrating its various functions. <![CDATA[<b>A biodiversity monitoring framework for South Africa</b>: <b>progress and directions</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400011&lng=en&nrm=iso&tlng=en Global declines in biodiversity, and the associated impacts on human wellbeing, have triggered national and international agreements to reduce or halt these trends. The Convention on Biological Diversity's 2002 commitment, 'to achieve, by 2010, a significant reduction in the current rate of biodiversity loss....', is an often cited example and has caused a flurry of activity in the development of biodiversity monitoring systems. At a national scale, South Africa's National Environmental Management: Biodiversity Act and associated legislation have highlighted the need for a national biodiversity monitoring framework. The National Biodiversity Strategy and Action Plan makes a significant contribution to the development of this framework. As South Africa begins to implement the action plan, a review of existing national monitoring programmes in terms of global and national biodiversity monitoring requirements is important. This paper presents the results of a review of these national programmes, to provide a broad overview, assess alignment with national and global requirements, evaluate gaps and discuss a way forward in the devising of a national biodiversity monitoring framework. We find that the National Biodiversity Strategy and Action Plan aligns well with the Convention on Biological Diversity's 2010 target objectives, but differs in terms of the indicators proposed. Existing national biodiversity monitoring programmes also exhibit these indicator differences and show several gaps in indicator development and data collation. These gaps raise concern around the country's ability to report on the Convention on Biological Diversity's 2010 target, but together with the sound platform provided by the National Biodiversity Strategy and Action Plan, provide a good indication of national priorities and a way forward through a combination of short-term achievable tasks and longer-term development of programmes. <![CDATA[<b>Progress towards marine ecosystem observing systems in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400012&lng=en&nrm=iso&tlng=en Marine ecosystem observing systems combine measurements, observations and models through a data management and interpretation process to provide information on the status of marine ecosystems. Both biotic and abiotic aspects of the marine environment need to be considered. Single variables typically can be used to represent aspects of the physical and chemical environment, but ecosystem indicators are required for the living components. There are no true marine ecosystem observing systems globally, because most observing systems focus on the physical environment. In South Africa, some fledgling systems are being developed, using the knowledge base provided by focused marine ecosystem research over the past 30 years. Further development should be based on international guidelines, which highlight three interrelated elements: (i) Measurements, obtained directly from ships, drifters or buoys, or remotely from satellites. In South Africa, sustained, long-term measurements are hampered by limited available ship's time, lack of suitable instruments, and insufficient qualified personnel. (ii) Models and other analytical tools to augment observations. South Africa is making progress in marine modelling, but not in marine data assimilation; qualified persons need to be attracted, trained and retained. (iii) Archived and disseminated data generated from measurements and models. The infrastructure and human and institutional capacity for data management and communication in South Africa needs to be enhanced. Existing programmes contribute towards the development of an effective marine ecosystem observing system, but its sustainability requires support at an institutional level. <![CDATA[<b>The changing water resources monitoring environment in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400013&lng=en&nrm=iso&tlng=en Fundamental reform of water law, introduced to South Africa through the enactment of the National Water Act of 1998, has major implications for monitoring water resources and information management. Previously, water resources management was highly centralized and largely supply driven. The new legislation is intended to promote equity, sustainability and economic efficiency, partly through devolved management. Monitoring, previously intended to support the development and operation of the national water infrastructure, now focuses on compliance with resource quality objectives, management targets and water use licence conditions at national, regional (catchment) and local levels. A new phase of management practice is envisaged in which water resource monitoring will require much greater attention to the interaction between the status of water resources, the effects of human activities and the response of management to the results of the monitoring process. Such integrated monitoring will need to cover the traditional fields of surface and groundwater quantity and quality, but will also include an increasing focus on the air and land phases of the hydrological cycle and the various human impacts. These new initiatives will require fresh approaches to appropriate governance for the crosscutting management of information. The Act provides for greater coordination, and various models to achieve this are emerging at local and regional level. Various partnerships and an action-learning approach are seen as essential elements of integrating different disciplines, institutions and business processes. <![CDATA[<b>Scaling up from site-based research to a national research and monitoring network</b>: <b>lessons from Tierberg Karoo Research Centre and other design considerations</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400014&lng=en&nrm=iso&tlng=en South Africa is in the process of setting up a national environmental observatory system (SAEON) to monitor and gain a predictive understanding of the effects of climate change and land use on biodiversity, carbon and nutrient fluxes, soils and sediments, primary and secondary productivity, hydrology and disturbance regimes. It is intended that the data should be archived, analysed and translated into information accessible to decision-makers. We present a case that illustrates the infrastructural needs and challenges for long-term research and then discuss optimal designs and collaborations required to detect change in many variables, land-use types and geographical areas of South Africa. <![CDATA[<b>Atmospheric observations and numerical weather prediction</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400015&lng=en&nrm=iso&tlng=en Today's 72-hour weather forecast is as accurate, globally, as the 24-hour forecast of the 1980s. The recent improvement in accuracy, for the southern hemisphere in particular, is remarkable. This achievement came about through scientific understanding of dynamical and physical processes in the atmosphere coupled with new and enhanced modelling techniques, increased availability of remote-sensing data from weather satellites, and progress in data assimilation techniques that incorporate weather observations into numerical prediction models. The great advances in computing power have also contributed significantly to the forecaster's performance. Further improvements in the accuracy and reliability of climate and weather forecasts are to be expected as a result of superior data observation and assimilation techniques and modelling. The challenge to the forecaster is to provide user-specific risk-management information on various time scales, so that the users of this information can realize the social and economic value of advanced weather and environmental predictions more fully. <![CDATA[<b>Integrated approach to nutrient cycling monitoring</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400016&lng=en&nrm=iso&tlng=en There are two issues of social importance in relation to nutrient cycling. The first is the depletion of nutrients in croplands and rangelands. The second is the overabundance of nutrients through the enhancement of inputs, particularly in freshwater bodies and coastal systems, which results in loss of biodiversity and ecosystem services through eutrophication. Nutrient cycling encompasses 15 or so elements, each with multiple chemical forms and phases, four media (air, soil, biomass and water) and many transformation and transport processes. It is not cost-effective to monitor them all, even in intensive research sites. The two key elements involved in both fertility loss and eutrophication are nitrogen and phosphorus; thus their changes in nutrient pools and fluxes need to be monitored. Key anthropogenic nitrogen contributions are through atmospheric deposition and liquid waste streams. A sensitive impact indicator is the nitrogen saturation index, which rises abruptly when the absorptive capacity of the landscape is exceeded. Key anthropogenic phosphorus inputs are agriculture and, in certain locations, mining and industry. Monitoring phosphorus fertilizer application rates and local-to-regional nutrient balances is useful because phosphorus is highly conserved in ecosystems. Measurement of nutrients associated with sediment fluxes in rivers is important for both nitrogen and phosphorus, as well as for carbon balance. To place current fluxes and perturbations in perspective, historical records have to be established. Additionally, tools such as isotopic tracers, which can be used unequivocally to differentiate between the natural and anthropogenic components of nutrient cycles, need to be explored. <![CDATA[<b>Monitoring soil erosion in South Africa at a regional scale</b>: <b>review and recommendations</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400017&lng=en&nrm=iso&tlng=en Loss of topsoil is one of the principal soil degradation problems confronting agriculture throughout South Africa and receives special attention by policy-makers. For effective prevention and remediation, the spatial extent of the problem has to be established and monitored. Recent developments in the application of remote sensing and GIS to the study of soil erosion offer considerable potential in this regard. This paper outlines key technologies available for monitoring, and highlights the problems to be solved at a regional scale. The status of the technologies used in South Africa are reviewed and the more recent studies related to soil erosion are presented in a comparative context. Spatial, temporal and measurement variabilities are major constraints in erosion assessment. Previous erosion studies conducted in South Africa at the regional scale have disregarded important erosion factors and have overvalued less important ones. Different processes and interactions are likely to emerge as dominant when crossing scale boundaries. Such considerations highlight the need to establish a methodological framework to guide and standardize future regional soil loss monitoring efforts. <![CDATA[<b>Long-term measurements of sulphur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in southern Africa using passive samplers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400018&lng=en&nrm=iso&tlng=en This paper reports the measurements of monthly mean gaseous sulphur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone at four remote sites-Louis Trichardt (South Africa), Cape Point (South Africa), Amersfoort (South Africa) and Okaukuejo (Namibia)- in southern Africa, over a period of nine to 11 years, using passive samplers. The 10-year mean sulphur dioxide concentrations varied from 0.43 parts per billion (ppb) at Okaukuejo to 2.8 ppb at Amersfoort. Nitrogen dioxide varied from 0.34 ppb at Okaukuejo to 2.5 ppb at Amersfoort, nitric acid from 0.23 ppb at Louis Trichardt to 0.90 ppb at Amersfoort, and ammonia from 1.2 ppb at Amersfoort to 1.5 ppb at Cape Point. Ozone exhibited a fairly constant high mean value of about 27 ppb throughout the region except for the Louis Trichardt site, with a relatively high 10-year mean of 35 ppb. The annual concentrations of all chemical species measured decreased from 1995 to 2001, after which they increased slightly. The large amounts of biofuels that are combusted on the continent, mainly in winter, substantially influence the concentrations of all measured species. The seasonal concentrations of all the gases seem to peak in winter and spring at all sites, except for ammonia at Cape Point and Okaukuejo, and sulphur dioxide at Cape Point, which peaks during the summer. Strong inter-annual variations were observed that prove the scientific value of decision-making based on long-term observations. <![CDATA[<b>The nutrient status of South African rivers</b>: <b>concentrations, trends and fluxes from the 1970s to 2005</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400019&lng=en&nrm=iso&tlng=en Eutrophication of river systems, resulting from nutrient enrichment, is globally considered to be one of the most serious threats to freshwater ecosystem services such as water quality and biodiversity. This study provides a comprehensive overview of the nutrient status of the 20 largest river catchments in South Africa, based on dissolved inorganic nitrogen (NO3- + NO2-) and phosphorus (PO4(3-)) long-term water quality monitoring data collected by the Department of Water Affairs and Forestry. Nutrient levels exceeding recommended water quality guidelines for plant life are observed in all of the rivers, except one. Additionally, dissolved-phosphorus levels exceeding recommended concentrations for aquatic animal life prevail episodically in all but 6 of the catchments. Alarmingly, statistically significant (P < 0.05) upward trends in dissolved PO4(3-) levels are found in almost 60% of the rivers evaluated. The most likely cause of increasing nutrient enrichment is effluent from dysfunctional sewage works and unsewered human settlements. This poses a serious and costly threat to water quality and biodiversity. Nutrient fluxes associated with agricultural runoff, representing loss of soil fertility, translate into fertilizer-equivalent costs exceeding several hundred million rands annually. <![CDATA[<b>Early to mid-Holocene South African Later Stone Age human crania exhibit a distinctly Khoesan morphological pattern</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000400020&lng=en&nrm=iso&tlng=en The sample of South African early to mid-Holocene Later Stone Age(LSA) human crania is small and quite fragmentary, limiting our knowledge of human craniofacial morphology for this period. Previous limited analyses have described the morphology displayed by these early crania as a combination of Khoesan and non-Khoesan traits. Although essentially Khoesan-like in terms of facial morphology, their overall large size and robust neurocranial structure were regarded as atypical of Khoesan craniofacial morphology, leading to questions about the role of these early populations in the ancestry of recent Khoesan populations. Here we provide a quantitative analysis in which we compare five well-preserved pre-5000 BP LSA crania with (i) a large sample of post-5000 BP LSA Khoesan crania; and (ii) a sample of crania from recent South African Bantu-speakers. We show that these pre-5000 BP crania fall comfortably within the range of variation observed for the post-5000 BP Khoesan sample, in terms of both size and shape, suggesting that distinctive Khoesan craniofacial morphology was already present in South African LSA populations by the first half of the Holocene.