Scielo RSS http://www.scielo.org.za/rss.php?pid=0038-235320130002&lang=es vol. 109 num. 3-4 lang. es http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200001&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200002&lng=es&nrm=iso&tlng=es South Africa has a long track record in Southern Ocean and Antarctic research and has recently invested considerable funds in acquiring new infrastructure for ongoing support of this research. This infrastructure includes a new base at Marion Island and a purpose-built ice capable research vessel, which greatly expand research opportunities. Despite this investment, South Africa's standing as a participant in this critical field is threatened by confusion, lack of funding, lack of consultation and lack of transparency. The research endeavour is presently bedevilled by political manoeuvring among groups with divergent interests that too often have little to do with science, while past and present contributors of research are excluded from discussions that aim to formulate research strategy. This state of affairs is detrimental to the country's aims of developing a leadership role in climate change and Antarctic research and squanders both financial and human capital. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200003&lng=es&nrm=iso&tlng=es South Africa has a long track record in Southern Ocean and Antarctic research and has recently invested considerable funds in acquiring new infrastructure for ongoing support of this research. This infrastructure includes a new base at Marion Island and a purpose-built ice capable research vessel, which greatly expand research opportunities. Despite this investment, South Africa's standing as a participant in this critical field is threatened by confusion, lack of funding, lack of consultation and lack of transparency. The research endeavour is presently bedevilled by political manoeuvring among groups with divergent interests that too often have little to do with science, while past and present contributors of research are excluded from discussions that aim to formulate research strategy. This state of affairs is detrimental to the country's aims of developing a leadership role in climate change and Antarctic research and squanders both financial and human capital. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200004&lng=es&nrm=iso&tlng=es South Africa has a long track record in Southern Ocean and Antarctic research and has recently invested considerable funds in acquiring new infrastructure for ongoing support of this research. This infrastructure includes a new base at Marion Island and a purpose-built ice capable research vessel, which greatly expand research opportunities. Despite this investment, South Africa's standing as a participant in this critical field is threatened by confusion, lack of funding, lack of consultation and lack of transparency. The research endeavour is presently bedevilled by political manoeuvring among groups with divergent interests that too often have little to do with science, while past and present contributors of research are excluded from discussions that aim to formulate research strategy. This state of affairs is detrimental to the country's aims of developing a leadership role in climate change and Antarctic research and squanders both financial and human capital. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200005&lng=es&nrm=iso&tlng=es South Africa is the world's third most biodiverse country. The system of protected areas, however, does not capture its biodiversity comprehensively. Local land-use planning processes, and the integration of spatial conservation assessments in these processes, have been proposed as an effective approach to conserving biodiversity outside of protected areas. However, an understanding of the day-to-day processes in local government and the role conservation does or could play, is lacking. We used social marketing, a strategic and analytic approach to influence people's behavioural choices, to investigate why biodiversity conservation maps have failed to provide the biodiversity protection envisaged and how land-use planners could be persuaded to use the maps effectively. We interviewed 24 officials in six Eastern Cape coastal municipalities. We found that in large municipalities the maps were used by environmental units, whereas in intermediate and small municipalities they were used primarily by the consultants that prepare municipal planning documents. The land-use planning system was not fully functional, because of a lack of capacity and importance accorded to the issue. We could not identify any benefits that land-use planners might perceive in using the maps that directly related to conservation. We found that the younger generation of officials showed less sensitivity to biodiversity concerns. Furthermore, we found the relationship to the political hierarchy to be pivotal. For conservation to succeed, new approaches - for example engaging with the land-use planning domain to include conservation assessments - will be necessary. Including political actors in the processes is crucial http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200006&lng=es&nrm=iso&tlng=es The antioxidant activity of the leaves and flowers of the Moringa oleifera plant were investigated and the results were compared to those of selected vegetables (cabbage, spinach, broccoli, cauliflower and peas). Antioxidant activity was determined by analysing the total phenolics content, total flavonoids content, reducing power and radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl free radical method. The total phenolics content of moringa was almost twice that of the vegetables and the total flavonoids content was three times that of the selected vegetables. The reducing power of moringa was higher than that of the vegetables and the percentage of free radicals remaining was lower compared with the vegetables. These results combined show that moringa is a good source of antioxidants. This finding also explains why moringa forms part of the diet of people in many developing countries, especially in the southern hemisphere. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200007&lng=es&nrm=iso&tlng=es Taxonomic revisions, monographs and floras are the most important, and often the only source of data for assessing the extinction risk of plants, with recent revisions contributing to more accurate assessments. The recently completed Red List of South African plants involved an overview of the taxonomic literature pertaining to the South African flora, providing an opportunity to identify critical gaps in taxonomic coverage. In this study we identified taxonomic research priorities for effective conservation of South African plants. Priorities were identified at genus level, according to time since last revision, level of endemism, collecting effort, proportion of taxa included in revisions, and specimen identification confidence. Although the results indicate that 62% of the flora has been recently revised, revisionary taxonomic output has declined drastically, particularly in the past 10 years. This decline is a result of a decrease in revisionary productivity per taxonomist and not a result of a decline in the number of working taxonomists. The family Aizoaceae is the top priority for taxonomic research with 55% of taxa in need of revision, followed by Hyacinthaceae with 34% of taxa not yet revised. Ericaceae, Euphorbiaceae, Rutaceae, Malvaceae, Asteraceae and Acanthaceae are also priorities with over 30% of taxa last revised before 1970. We recommend the reinstatement of the Flora of Southern Africa project in an online format in order to centralise South Africa's existing taxonomic information and reinvigorate revisionary taxonomic study. This project will allow South Africa to fulfil its commitments to the Convention on Biodiversity by achieving Target 1 of the Global Strategy for Plant Conservation. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200008&lng=es&nrm=iso&tlng=es We report on the use of modern spatial computing technology in the development of spatial tourism policy and planning in the context of a bounded resource base. We refer briefly to provincial tourism development policy, expand on the tourism marketing framework and use the express tourist preferences to determine suitability indicators or attraction features for a spatial tourism resource base, paying special attention to the conceptual foundations of attraction and the mapping of tourism potential variables. We applied the methodology to a combination of tourism products in the Western Cape Province of South Africa in an approach that involved applying the spatial multiple criteria evaluation through the weighted linear combination of spatial factor layers as images in a geographical information system. We performed an analysis of the gap between tourism potential and tourism resource provision at a spatial resolution of individual towns' spheres of influence, as represented by Thiessen polygons. The outcome in map format demonstrates the applicability of the technique to the Western Cape. The fine-scale spatial result was analysed for its strategic planning implications. Our results are useful for entrepreneurial and regulatory planning and can be replicated in different spatial locations if the appropriate database can be constructed. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200009&lng=es&nrm=iso&tlng=es Multispectral remote sensing application in thematic urban land-use or land-cover (LULC) classification has gained popularity in the recent past. However, as a result of the complexity of urban landscapes and spectral limitations in commonly used imagery, accurate urban LULC classification has often been impeded by confusion of spectra among multiple urban LULC types. The emergence of multispectral aerial photographs, characterised by high spatial resolution and multispectral information, offers great potential for LULC classification. In this study, we hypothesised that textural information using optimum Haralick textural features inherent in multispectral aerial photographs can be used to generate reliable land-cover maps in heterogeneous urban landscapes. Haralick textural feature optimisation and object-based classification were used to discriminate diverse urban LULC types. Grey-level co-occurrence matrix (GLCM) Entropy, GLCM Mean and GLCM Angular Second Moment texture features were used to discriminate different LULC types while the Jeffreys-Matisuta separability analysis was used to identify optimum thresholds for the development of object-based classification rules. Results from object-based classification were also compared to classification output using the aerial photograph's spectral information. Results show that use of both object-based Haralick textural features and the spectral characteristics on multispectral aerial photographs can be used to generate reliable LULC classes. Classification based on object-based Haralick textural features produced higher accuracy than that based on spectral information. Multispectral aerial photographs using both object-based Haralick textural features and spectral information offer great potential in mapping urban landscapes often characterised by heterogeneous cover types. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200010&lng=es&nrm=iso&tlng=es Sea level variability in the coastal ocean affects water levels in adjacent estuaries over a wide range of periods and to varying distances landward. An assessment is given here of the responses of a number of South African estuaries, focusing on tidal and subtidal periods where the dominant effects are found and the necessary data are available. Shorter period inputs tend to be limited to mouth regions and require more detailed, higher frequency data. Subtidal fluctuations, in particular those caused by coastal trapped waves, play an important part in the dynamics of estuaries in the Western Cape and Eastern Cape. In many cases their influence dominates tidal oscillations farther upstream, and it is apparent that such fluctuations must be considered in any assessment of estuarine characteristics, and indeed their upstream extent. Nonetheless, it should be emphasised that each estuary has unique properties, and must be assessed individually. Sea level variability changes dramatically north of the Kei Estuary, and particularly off the coast of KwaZulu-Natal. Unfortunately, few measurements were available from these estuaries, but the mouth conditions of the estuaries and the build-up of river flow appear to be important factors in resulting estuary water levels. These results show that using only tidal variations in the sea can result in very misleading conclusions about concurrent water levels in estuaries. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200011&lng=es&nrm=iso&tlng=es Moringa [Moringa oleifera) is a plant that is commonly consumed as a nutritional supplement by some communities in South Africa. Contamination of moringa with toxic heavy metals could be deadly for consumers. However, some metal elements are essential for consumers in trace amounts. We therefore investigated the concentrations of heavy metals, including major and trace nutrient elements, in the soil and in the leaves and flowers of moringa grown on two farms in South Africa. After total digestion in the microwave, the concentrations of metals were determined using inductively coupled plasma optical emission spectroscopy. No toxic heavy metals were detected in the leaves and flowers of moringa. On average, moringa contained higher concentrations of Ca (18 500 mg/kg) and Mg (5500 mg/kg) than selected vegetables (spinach, cabbage, cauliflower, broccoli and peas). The concentrations of other major nutrients in moringa were similar to those of the vegetables. Based on reports of antioxidant activity, we also investigated the concentrations of flavonols (myricetin, quercetin, kaempferol) in moringa leaves and flowers in comparison with the selected vegetables. A high concentration of flavonols is related to antioxidant activity. Plant and vegetable materials were extracted under reflux using an acidified methanol (1% HCl) solution and the flavonols were identified and quantified using reverse-phased high-performance liquid chromatography with UV detection. Moringa leaves had higher concentrations of myricetin (1296.6 mg/kg), quercetin (1362.6 mg/kg) and kaempferol (1933.7 mg/kg) than vegetables (spinach: myricetin 620.0 mg/kg, quercetin 17.9 mg/kg, kaempferol 215.3 mg/kg). No major differences were found between the plants growing on the two farms. Moringa is thus nutritionally valuable and safe to consume. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200012&lng=es&nrm=iso&tlng=es Complementary medicines containing the succulent herb Sceletium are being sold without information regarding their phytochemical contents, which is essential for the quality control of medicines. Furthermore, several different Sceletium species exist and little has been reported on the alkaloidal identities and contents of the various species. We therefore conducted phytochemical investigations on six selected Sceletium specimens, identified on the basis of their venation pattern as either 'emarcidum' or 'tortuosum' type. The tortuosum type consisted of S. tortuosum, S. expansum and S. strictum, whereas the emarcidum type consisted of S. emarcidum, S. exalatum and S. rigidum. Analysis was conducted by high-performance liquid chromatography with UV and alkaloids were identified by online mass spectroscopy. S. tortuosum and S. expansum samples contained mesembrine together with mesembrenone, mesembranol and epimesembranol, although the latter two alkaloids were present in low concentrations in S. expansum. S. strictum contained mesembrenone, mesembrine and either 4'-0-demethylmesembrenone or 4'-0-demethylmesembrenol. The emarcidum type specimens showed a complete absence of the major alkaloid mesembrine, as well as the other alkaloids usually associated with these species. In only one of the species of the emarcidum type - S. exalatum - two peaks corresponded to either 4'-0-demethylmesembrenone or O-methyljoubertiamine and either 4'-O-demethylmesembrenol or N-demethylmesembrenol, respectively. This study clearly indicates that not all Sceletium species contain the mesembrine-type alkaloids usually associated with Sceletium. It is thus important to identify the correct Sceletium species to ensure correct alkaloidal content for the manufacture and quality control of products containing this plant material. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200013&lng=es&nrm=iso&tlng=es The richness of fossil tetrapods from the Beaufort Group of South Africa has enabled biostratigraphic subdivision of this Permo-Triassic succession, with global applicability. Despite being the thickest of the seven biozones recognised, attempts at further subdivision of the Middle Permian Tapinocephalus Assemblage Zone (Abrahamskraal Formation) have not been successful, largely because the exact stratigraphic ranges of fossil taxa are unknown. This gap in knowledge has limited stratigraphic correlation of the Abrahamskraal Formation and hindered understanding of Middle Permian Karoo basin development. Currently, the lowermost Beaufort Group is split between an eastern and a western stratigraphic scheme and, because of poor outcrop and the relative paucity of fossils in the east, stratigraphic correlation between the two areas has been uncertain. Recent fossil discoveries of the parareptile Eunotosaurus africanus in the Eastern Cape and Free State provinces have extended its known geographic range in the east. An additional specimen from the lower Middleton Formation in the Eastern Cape has, for the first time, enabled the biostratigraphic correlation of this unit with the Poortjie Member of the Teekloof Formation in the west. These finds confirm the diachroneity of the boundary between the marine Ecca Group and the terrestrial Beaufort Group. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000200014&lng=es&nrm=iso&tlng=es Severe coastal erosion occurred along the KwaZulu-Natal coastline between mid-May and November 2011. Analysis of this erosion event and comparison with previous coastal erosion events in 2006/2007 offered the opportunity to extend the understanding of the time and place of coastal erosion strikes. The swells that drove the erosion hotspots of the 2011 erosion season were relatively low (significant wave heights were between 2 m and 4.5 m) but of long duration. Although swell height was important, swell-propagation direction and particularly swell duration played a dominant role in driving the 2011 erosion event. Two erosion hotspot types were noted: sandy beaches underlain by shallow bedrock and thick sandy beaches. The former are triggered by high swells (as in March 2007) and austral winter erosion events (such as in 2006, 2007 and 2011). The latter become evident later in the austral winter erosion cycle. Both types were associated with subtidal shore-normal channels seaward of megacusps, themselves linked to megarip current heads. This 2011 coastal erosion event occurred during a year in which the lunar perigee sub-harmonic cycle (a ±4.4-year cycle) peaked, a pattern which appears to have recurred on the KwaZulu-Natal coast. If this pattern proves true, severe coastal erosion may be expected in 2015. Evidence indicates that coastal erosion is driven by the lunar nodal cycle peak but that adjacent lunar perigee sub-harmonic peaks can also cause severe coastal erosion. Knowing where and when coastal erosion may occur is vital for coastal managers and planners.