Ecosystems In South Africa Research Articles

Monitoring changes in South Africa’s surface water extent for reporting Sustainable Development Goal sub-indicator 6.6.1.a

For the first progress reporting on the Sustainable Development Goal sub-indicator 6.6.1a in 2020, the South African and global statistics related to wetlands were compared. Firstly, in terms of the total wetland extent, the South African National Wetland Map version 5 (NWM5) represented 87% more inland, surface aquatic ecosystems than the Global Surface Water (GSW) product. More than half of the lacustrine systems and none of the palustrine and arid systems in NWM5 are represented in the GSW layer. Secondly, in terms of changes in the extent of wetlands, both the global and South African statistics showed a decreasing trend in the spatial extent of surface aquatic ecosystems in South Africa. These trends should be further investigated against systematic assessments of decadal drought periods. The hydroperiod information (permanent, seasonal and ephemeral inundation periods) of the GSW products show that South African lacustrine wetlands do not have a single dominant class (≥70% of the extent of a polygon) of inundation, but consist of a mosaic of these classes.Significance:
 
 The South African National Wetlands Map version 5 represents 87% more of the extent of lacustrine, palustrine and arid wetlands than the Global Surface Water products that are used for progress reporting on the Sustainable Development Goal sub-indicator 6.6.1a.
 South African and global statistics suggest a decline in the extent of lacustrine wetlands, although a systematic comparison with decadal drought periods is required to confirm these trends.
 South African lacustrine wetlands consist of a mosaic of hydroperiod classes (permanent, seasonal and ephemeral inundation periods) with no individual class dominating (≥70% of the extent of) wetlands polygons.

Drought Disaster Risk Adaptation through Ecosystem Services-Based Solutions: Way Forward for South Africa

Ecosystem services refer to the direct and indirect benefits to humanity from an ecosystem. The ability to spatially incorporate multiple biophysical environments is crucial to ecosystem services, thus promoting cooperation between science and policy in seeking solutions to global challenges, including drought disasters. Therefore, understanding ecosystem services, for instance, from forest/vegetation in view of contributing to drought disaster risk adaptation is critical to human-nature interactions and proper sustainable conservation thereof. No known study has been done on ecosystem services and their contributions to drought management or other climate adaptation in South Africa. This study aimed at quantifying drought disaster risk adaptation based on ecosystem services in South Africa. It was identified that ecosystem services to society have been directly affected by anthropogenic and natural phenomena, thereby influencing drought severity and its impacts. These impacts and their associated risks are evident globally, including in South Africa. We found out that ecosystems in South Africa have been affected and extremely vulnerable to recurrent natural disasters, such as droughts. To achieve long-term solutions to such drought-related risks and challenges, feedback mechanisms between human-natural and related factors and ecosystem services-based drought adaptation need to be understood and planned. Timely spatiotemporal assessment, planning and management strategies need to be considered to find solutions or ways forward to South Africa in combating drought disasters.

Plant diversity and conservation value of wetlands along a rural–urban gradient

Background: Wetlands are the most threatened ecosystem in South Africa despite the range of ecosystem goods and services they provide. A significant cause of wetland destruction and degradation is a lack of understanding, by planners, policymakers and developers, of their ecological and socio-economic importance.Objectives: This study assessed the floristic composition and diversity of wetlands in the former Tlokwe Municipal area along a rural–urban gradient.Methods: Fourteen wetland sites were surveyed along an urbanisation gradient. Vegetation surveys were done in quadrats along transects in each wetland recording the cover-abundance of each species. The data were analysed by using ordinations, similarity percentages, and the adjusted Floristic Quality Assessment Index.Results: Overall, the proportional species composition of urban and rural wetlands was mainly similar. Trends indicated that the alpha diversity increased with both habitat size and heterogeneity along a rural–urban gradient. In all wetlands, indigenous species were the most abundant, with the highest score in the largest urban wetland. The floristic quality varied widely along the gradient with none of the sites in pristine condition.Conclusion: The similarity in species composition and floristic quality of the wetlands, as well as the high levels of indigenous species richness, indicated that urban wetlands are worthy of conservation. However, the signs of disturbances and the presence of alien species means that restoration strategies need to be implemented to improve the quality of the wetlands.

Microbial substrate stoichiometry governs nutrient effects on nitrogen cycling in grassland soils

Human activities have increased nitrogen (N) and phosphorus (P) inputs in terrestrial ecosystems and altered carbon (C) availability, shifting the stoichiometry of microbial substrates in soils, such as the C:N:P ratios of the dissolved organic matter pool. These stoichiometric deviations between microbial biomass and its substrate may control microbial processes of N cycling. We studied the effects of this stoichiometric mismatch using a full factorial N and P addition experiment replicated in six grassland ecosystems in South Africa, the USA, and the UK. We found that N and P addition changed the dissolved organic matter C:N ratio, but not the C:N ratio of the soil microbial biomass. Compared to P addition, N addition decreased microbial N acquisition via non-symbiotic N2 fixation by −55% and increased microbial N release via net N mineralization by +134%. A possible explanation is that the dissolved elements, e.g., dissolved organic C (DOC) and dissolved total N (DN), serve as the main microbial substrate and its C:N ratio defines whether N is scarce or abundant with respect to microbial demands. If N is available in excess relative to microbial demands, net N mineralization increases. In contrast, when N is scarce, immobilization outweighs release decreasing net N mineralization. However, the activity of leucine aminopeptidases, which decompose peptides, was not affected by nutrient additions. Further, C rather than P availability may control the rates of non-symbiotic N2 fixation in the six studied grassland sites. In conclusion, globally increasing nutrient inputs change processes of microbial N acquisition and release in grassland ecosystems and these changes are largely driven by shifts in substrate stoichiometry.

Rates and patterns of habitat loss across South Africa’s vegetation biomes

The loss of natural habitat resulting from human activities is the principal driver of biodiversity loss in terrestrial ecosystems globally. Metrics of habitat loss are monitored at national and global scales using various remote sensing based land-cover change products. The metrics go on to inform reporting processes, biodiversity assessments, land-use decision-making and strategic planning in the environmental and conservation sector. We present key metrics of habitat loss across South Africa at national and biome levels for the first time. We discuss the spatial patterns and trends, and the implications and limitations of the metrics. Approximately 22% of the natural habitat of South Africa has been lost since the arrival of European settlers. The extent and the rate of habitat loss are not uniform across South Africa. The relatively mesic Grassland, Fynbos and Indian Ocean Coastal Belt biomes have lost the most habitat, while the arid Nama-Karoo, Succulent Karoo and Desert have lost the least. Rates of loss increased across all biomes in recent years (2014–2018), indicating that the historical drivers of change (i.e. expansion of croplands, human settlements, plantation forestry and mining) are intensifying overall. We should caution that the losses we report are conservative, because the land-cover change products do not capture degradation within natural ecosystems. Preventing widespread biodiversity losses and securing the benefits we derive from biodiversity requires slowing and preventing further habitat degradation and loss by using existing land-use planning and regulatory tools to their full potential.
 Significance:
 
 The loss of natural habitat resulting from human activities is the principal driver of biodiversity loss in terrestrial ecosystems in South Africa.
 Monitoring trends and patterns of habitat loss at a national scale provides a basis for informed environmental decision-making and planning, thus equipping civil society and government to address habitat loss and protect biodiversity while also meeting key development and socio-economic needs.
 
 Open data set:
 https://doi.org/10.15493/SAEON.FYNBOS.10000011

A review of Capezoum Adlbauer, 2003 (Coleoptera: Cerambycidae) with the description of two new species from the Succulent Karoo ecosystem in South-Africa.

Capezoum Adlbauer, 2003 is known only from male specimens. Herein, we describe two new species: Capezoum richardi sp. nov. and C. brunneopunctatus sp. nov., from the Northern Cape region in South-Africa. The discovery of these new species, one of them represented by both sexes, allowed us to describe the hitherto unknown female. Moreover, the genus is transferred to the tribe Xystrocerini and a key to the species of the genus is provided. Lastly, the position of Mythozoum Thomson, 1878 in Cerambycidae is discussed.

Using very‐high‐resolution satellite imagery and deep learning to detect and count African elephants in heterogeneous landscapes

AbstractSatellites allow large‐scale surveys to be conducted in short time periods with repeat surveys possible at intervals of <24 h. Very‐high‐resolution satellite imagery has been successfully used to detect and count a number of wildlife species in open, homogeneous landscapes and seascapes where target animals have a strong contrast with their environment. However, no research to date has detected animals in complex heterogeneous environments or detected elephants from space using very‐high‐resolution satellite imagery and deep learning. In this study, we apply a Convolution Neural Network (CNN) model to automatically detect and count African elephants in a woodland savanna ecosystem in South Africa. We use WorldView‐3 and 4 satellite data –the highest resolution satellite imagery commercially available. We train and test the model on 11 images from 2014 to 2019. We compare the performance accuracy of the CNN against human accuracy. Additionally, we apply the model on a coarser resolution satellite image (GeoEye‐1) captured in Kenya, without any additional training data, to test if the algorithm can generalize to an elephant population outside of the training area. Our results show that the CNN performs with high accuracy, comparable to human detection capabilities. The detection accuracy (i.e., F2 score) of the CNN models was 0.78 in heterogeneous areas and 0.73 in homogenous areas. This compares with the detection accuracy of the human labels with an averaged F2 score 0.77 in heterogeneous areas and 0.80 in homogenous areas. The CNN model can generalize to detect elephants in a different geographical location and from a lower resolution satellite. Our study demonstrates the feasibility of applying state‐of‐the‐art satellite remote sensing and deep learning technologies for detecting and counting African elephants in heterogeneous landscapes. The study showcases the feasibility of using high resolution satellite imagery as a promising new wildlife surveying technique. Through creation of a customized training dataset and application of a Convolutional Neural Network, we have automated the detection of elephants in satellite imagery with accuracy as high as human detection capabilities. The success of the model to detect elephants outside of the training data site demonstrates the generalizability of the technique.

IP Regulation in South Africa – Evolution, Current Status and comparison with SADC region countries

Este artículo revisa y analiza de manera crítica el desarrollo de las regulaciones de propiedad intelectual relacionadas con patentes de productos farmacéuticos en Sudáfrica con un enfoque particular en los casos clave que han dado forma a la evolución y al estado actual del ecosistema de propiedad intelectual en patentes en Sudáfrica. En el documento se encontrará una evaluación técnico-jurídica pero también una narración sociopolítica de las circunstancias, posiciones políticas y avances jurisprudenciales clave que han dado forma a la respuesta de Sudáfrica frente a los grandes retos en materia de enfermedades comunicables y de salud pública, en especial de VIH- sida que ha debido enfrentar en las últimas décadas. Un breve recuento de las regulaciones y prácticas en los países de la región SADC ha sido incluido como ejercicio comparativo examinando la legislación y los procedimientos adelantados. Adicionalmente, se ha agregado la necesaria mención de India, ya que además de ser uno de los principales proveedores de medicamentos patentados y genéricos, ha sido un referente para la evolución legislativa y jurisprudencial de la región.

Remotely sensed characterization of Acacia longifolia invasive plants in the Cape Floristic region of the Western Cape, South Africa

Acacia longifolia, like any other invasive species, poses a threat to the natural ecosystems in South Africa and beyond. In South Africa, the species is reported to cause significant loss to vegetation biodiversity and is associated with high water use. It remains a challenge to understand the extent of their invasion in complex landscapes, where the use of ground-based surveys is difficult. Considering the heterogeneity and complexity of hydrological and ecological processes at catchment scale, the implementation of remote sensing to detect the distribution of these species becomes critical for continuous monitoring of their extent and associated impacts. We, therefore, aim at species-specific characterization of the spatial distribution of Acacia longifolia invasive wood species at catchment scale within the Cape Floristic region located in the Western Cape Province, using Sentinel 2 remotely sensed data. Overall, the distribution of A. Longifolia was found to be patchy and heterogeneous, across the catchment. However, the main hot spots were detected within the fynbos vegetation, low-lying areas, as well as along the southern coastal belt. Although the catchment is predominantly under cultivation, A. longifolia was found to occupy almost 10% of its area. Classification using combined variables, using both vegetation indices and bands produced the highest overall accuracy of 88.66%, than when bands (66.19%) and indices (76.05%) were used as independent dataset. For example, the producer’s classification accuracy of A. longifolia increased by almost 15%, whereas the user’s increased by almost 10% from spectral bands accuracies. The classification of A. longifolia was primarily attributed to near-infrared, short wave-infrared (centered at 2190 nm), red edge (705 and 740 nm), as well as, chlorophyll vegetation index, the leaf water content index, and normalized difference vegetation index, derived using the near-infrared and red-edge band (at 740 nm) variables. The findings of this study underscore the relevance of satellite-based remote sensing in monitoring invasions in natural ecosystems and can be used as baseline information for invasive-species clearing endeavors in the area.

Alnus glutinosa (Betulaceae) in South Africa: invasive potential and management options

Invasive alien plants cause major environmental and economic impacts and preventing the establishment and spread of emerging invaders is crucial. Black Alder (Alnus glutinosa) is well established as a widespread invader in a number of countries, notably the USA and New Zealand, and was recently detected invading riparian ecosystems in South Africa's Western Cape Province. We review the introduction history, current distribution and invasion potential (via species distribution and risk analysis) of Black Alder in South Africa, collate information on its biology, environmental impacts and options for management from its native and invaded range, assess its potential range and management attempts in South Africa, and provide guidelines for effective management. Furthermore, correlative modelling predicted areas of the southern and eastern part of South Africa to have suitable environments for Black Alder establishment. However, water availability will likely limit the species to riparian areas, and areas where the annual rainfall exceeds 500 mm per annum. We estimated control costs to be minimum R 82 000 per month, and the vigorous resprouting nature of Black Alder and its riparian zone preferences presents large management challenges. We propose that Black Alder should be listed as Category 1a under the National Environmental Management: Biodiversity Act (NEMBA) in South Africa. We advise that riparian areas in particular be monitored closely to prevent Black Alder from becoming a widespread invader.

The evolution and alignment of institutional shareholder engagement through the King and CRISA reports

Purpose The purpose of this study is to provide a high-level review of the evolution of shareholder activism and institutional investor engagement in the corporate governance ecosystem in South Africa. Furthermore, it specifically seeks to explain the incorporation of such aspects into the various key codes and reports on corporate governance in South Africa since 1994. Design/methodology/approach Historical narrative and analysis. Findings This study highlights how shareholder activism and institutional investor engagement in the corporate governance ecosystem have been considered and addressed in South Africa since the publication of the First King Report in 1994. The progress that has been made specifically with regard to the introduction of a code for institutional investors is highlighted. The study ultimately acknowledges that this evolution is a continuing journey on the road to stakeholder inclusivity and engagement, and then concludes that the specific role and impact of institutional investors, particularly given some of the recent corporate governance failures, will require further consideration going forward. This should ensure the continued alignment of all stakeholders and assist in making the necessary improvements to the overarching governance framework and attendant culture. Originality/value This study is a part of a special issue that looks at the contribution of the King reports to governance globally.

National Wetland Map 5: An improved spatial extent and representation of inland aquatic and estuarine ecosystems in South Africa

The improved representation of freshwater and estuarine ecosystems and associated data was a key component of the 2018 National Biodiversity Assessment, and is an essential step in enhancing defensible land use planning and decision making. This paper reports on the enhancement of the National Wetland Map (NWM) version 5 for South Africa and other data layers associated with the South African Inventory of Inland Aquatic Ecosystems. Detail is provided on (i) the extent of wetlands mapped in NWM5, compared to previous versions of the NWMs; (ii) the improved extent of inland wetlands mapped in focus areas in NWM5 relative to NWM4; (iii) the type of cover associated with the wetlands (inundated, vegetated or arid); (iv) the ecotone between rivers and estuaries; and (v) level of confidence for the inland wetlands in terms of how well the extent and hydrogeomorphic units were captured for each sub-quaternary catchment of South Africa. A total of 4 596 509 ha (3.8% of South Africa) of inland aquatic ecosystems and artificial wetlands have now been mapped, with NWM5 delineating 23% more inland wetlands (2 650 509 ha or 2.2% of SA) compared with NWM4. The estuarine functional zone, which encapsulates all estuarine processes, and associated habitats and biota, was refined for 290 systems totalling 200 739 ha, with the addition of 42 micro-estuaries totalling 340 ha. Nearly 600 000 ha (0.5% of SA) of artificial wetlands were mapped in SA. Inland wetlands are predominantly palustrine (55%), with some arid (34%) and a few inundated systems (11%). Ecotones between rivers and estuaries, ecotones where biota and processes continuously vary from freshwater to estuarine, formed a small fraction (<1.5%) of river total extent (164 018 km). Most inland wetlands (~70%) had a low confidence ranking for designation of extent and typing, because they were not mapped by a wetland specialist and not verified in the field. Future improvements of the map should be focused on catchment-based improvements, particularly in strategic water-source areas, areas of high development pressure and those with low confidence designation.

Diet of Glossogobius callidus (Teleostei: Gobiidae) in freshwater impoundments in the Sundays River Valley of the Eastern Cape, South Africa

Despite the high abundance of the gobiid fish Glossogobius callidus in many freshwater ecosystems in South Africa, very few studies have assessed the biology and ecology of the species. Here, we investigated the diet of G. callidus populations sourced from Sundays River irrigation ponds. A total of 571 fish grouped into two size classes (TL, range ± SD: juveniles of 20–60 ± 45 mm; adults of 61–140 ± 85 mm) were sampled by seine netting; prey items were removed from the guts and identified and sorted to obtain dietary information for each prey group. Of the examined guts, 97% contained prey comprising 17 taxa within 10 taxonomic groups. Teleosts were identified to species level, whereas most dietary components were identified to a broad taxonomic group. Aquatic invertebrates were the most important component of the diet of G. callidus, but the index of relative importance (%IRI) of dominant invertebrate taxa varied according to ontogenetic stage of G. callidus and season. Prey taxa included: Diptera, Hemiptera, Trichoptera, Odonata, Cladocera, Copepoda, Hydracarina, Amphipoda, Mollusca and Teleostei. Dipteran prey taxa were consistently encountered in both size classes and across all seasons. G. callidus can therefore be regarded as a generalist invertivore.

The evidence ecosystem in South Africa: growing resilience and institutionalisation of evidence use

The evidence-informed approach to policy-making and implementation is, at its core, about better decisions for a better future. It is focused on the effective use of scarce resources, on avoiding harm and maximising good. It is grounded in principles of equity and equality, of accountability and transparency. Given these characteristics, for those of us who work in this field, there is arguably a moral, economic, social and political case for paying closer attention to evidence-informed decision-making ecosystems in the South. Evidence-based policy and implementation, or evidence-informed decision-making in line with the most recent thinking, is often framed from two inter-related but limited perspectives: first, it is viewed as an approach that has originated from ‘developed’ Northern countries, and second, it is conceptualised as a technical intervention. However, there has been a shift in how the approach is conceived, moving away from assumptions that it is an intervention implemented from outside, from the North, for the benefit of the South. As part of this shift, certain initiatives in Africa have gained greater momentum. It is in acknowledging that there are different ways to think (epistemic diversity) about Southern evidence-informed decision-making, that this work has arisen. It seizes on the opportunity to view evidence-informed decision-making in a new light, exploring the evidence ecosystems in the South as systems strongly influenced by, but not defined by, Northern stimuli, including, but not limited to, technical interventions. This work set out to describe the evidence ecosystem in South Africa. In doing so, it finds that the ecosystem is increasingly resilient despite some limitations. It has strong structural foundations, includes many diverse organisations, is supported by not inconsiderable investment, is enabled by growing and significant capacity, contains iterations and innovations, and last but not least, incorporates complexity that gives the ecosystem resilience. The work demonstrates, through its focus on South Africa’s evidence ecosystem, that the global movement has much to learn from the South.

Comparison of two remote sensing models for estimating evapotranspiration: algorithm evaluation and application in seasonally arid ecosystems in South Africa

Remote sensing tools are becoming increasingly important for providing spatial information on water use by different ecosystems. Despite significant advances in remote sensing based evapotranspiration (ET) models in recent years, important information gaps still exist on the accuracy of the models particularly in arid and semi-arid environments. In this study, we evaluated the Penman-Monteith based MOD16 and the modified Priestley-Taylor (PT-JPL) models at the daily time step against three measured ET datasets. We used data from two summer and one winter rainfall sites in South Africa. One site was dominated by native broad leaf and the other by fine leafed deciduous savanna tree species and C4 grasses. The third site was in the winter rainfall Cape region and had shrubby fynbos vegetation. Actual ET was measured using open-path eddy covariance systems at the summer rainfall sites while a surface energy balance system utilizing the large aperture boundary layer scintillometer was used in the Cape. Model performance varied between sites and between years with the worst estimates (R2<0.50 and RMSE>0.80 mm/d) observed during years with prolonged mid-summer dry spells in the summer rainfall areas. Sensitivity tests on MOD16 showed that the leaf area index, surface conductance and radiation budget parameters had the largest effect on simulated ET. MOD16 ET predictions were improved by: (1) reformulating the emissivity expressions in the net radiation equation; (2) incorporating representative surface conductance values; and (3) including a soil moisture stress function in the transpiration sub-model. Implementing these changes increased the accuracy of MOD16 daily ET predictions at all sites. However, similar adjustments to the PT-JPL model yielded minimal improvements. We conclude that the MOD16 ET model has the potential to accurately predict water use in arid environments provided soil water stress and accurate biome-specific parameters are incorporated.

Diatrypaceae species overlap between vineyards and natural ecosystems in South Africa

Abstract Diatrypaceae species collected from 33 woody hosts occurring near vineyards were characterised. Plants showed symptoms of dieback, necrosis and cankers. Phylogenetic analyses based on ITS-rDNA and the β-tubulin gene separated the 265 isolates obtained into 14 species. The five most frequently encountered species, Cryptovalsa ampelina, Eutypa cremea, Eutypa lata, Eutypella citricola and Eutypella microtheca, were also found on grapevine in a previous study in South Africa. Several plant species, therefore, serve as hosts for these pathogens. First reports in South Africa include Cryptosphaeria ligniota, Eutypella leprosa and Eutypella australiensis. Host ranges of Cryptosphaeria multicontinentalis, Eu. australiensis and Eu. microtheca were also expanded. Diatrypaceae species caused brown discolouration when inoculated onto wounded grapevine tissues, which suggests that cross-infections are possible between grapevine and other woody hosts. Campelina., Eu. microtheca and Eu. citricola were the most virulent species and their virulence was comparable to that of Eu. lata, a known pathogen causing Eutypa dieback.

Elephant effects on treefall and logfall highlight the absence of megaherbivores in coarse woody debris conceptual frameworks

Despite the importance of coarse woody debris (CWD) in woody ecosystems, conceptual frameworks of its dynamics currently exclude the role of the megaherbivores, focusing instead on the role of insects, disease, fire, wind and droughts. However, recognizing the ecological roles of the megaherbivores is one of the most urgent contemporary issues, particularly as their decline will likely have unanticipated outcomes at the ecosystem-level. Here we used sites with and without elephants in a semi-arid woodland ecosystem in South Africa to test whether elephants changed the quantitative and qualitative features of the CWD profile in relation to other wood producers. We show that elephants increased the abundance of CWD, influenced its quality by toppling mostly maturing trees, and changed the distribution of large woody items along gentle hillslopes. Surprisingly, and despite the recognized importance of both CWD and elephants for biodiversity, there is almost no published data on the role of elephants in shaping wood-living communities by changing fallen woody debris dynamics. Our study contributes towards developing a broader conceptual framework of CWD dynamics that includes the role of megaherbivores and provides a novel view of the ecological consequences of the loss of the Pleistocene megaherbivores. Our findings have important implications for CWD restoration efforts in transformed systems that previously supported megaherbivores.

Water temperature and riverine ecosystems: An overview of knowledge and approaches for assessing biotic responses, with special reference to South Africa

Available information pertaining to water temperature in riverine ecosystems is examined and consolidated into an overview that describes the spatial and temporal variation in water temperature, the importance of water temperature in lotic ecosystems, the measurement and modelling of water temperature, anthropogenic factors that modify water temperature, the effects of temperature changes on the physical and chemical characteristics of water; and on aquatic organisms and ecosystems. Methods for assessing the effects of temperature changes on aquatic organisms are discussed and current water temperature guidelines for the protection of aquatic ecosystems are outlined. This paper highlights the complexity of water temperature in the aquatic environment and the importance of understanding the spatio-temporal variability in water temperature and the variable responses of aquatic organisms to thermal stress. Anthropogenic modifiers of the thermal regime, which include heated discharges, flow modifications, riparian vegetation removal and global climate change; present ongoing threats to aquatic ecosystems. Whilst Northern Hemisphere information on water temperature is plentiful, this overview has identified the huge gap that exists in temperature-related data in South Africa. Without baseline data on water temperature and the thermal requirements of aquatic organisms, it is extremely difficult to adequately manage aquatic ecosystems. The risk of increasingly harsh conditions caused by greater water demands and climate change accentuates the need for a greater understanding of the thermal conditions in aquatic ecosystems in South Africa and the requirements and triggers of the associated aquatic biota. Future directions for thermal research are described.

The dispersal and spread of invasive alien Myrtillocactus geometrizans in the southern Karoo, South Africa

The invasion of Cactaceae into semi-arid and arid ecosystems in South Africa is of conservation concern, particularly those species that produce juicy fruit that attract avian frugivores.Bird-dispersed Bilberry Cactus (Myrtillocactus geometrizans) is invading natural areas around the village of Prince Albert and appears to have originated from a cactus collection that was established about 40 years ago, and from there has spread locally over an area of about 1 km2. We surveyed the invaded area, recording a GPS point and size data for each of 156 Bilberry Cactus plants.The height-class distributions of Bilberry Cactus plants recorded in our survey suggest that recruitment is episodic rather than continuous or annual, with clearly defined invasion, or survival events.As this cactus species matures slowly and recruits episodically, the rate of the invasion has been slow. However, the presence of suitable pollination and dispersal mutualists and indigenous shrubs that serve as protective host plants suggest that the populations will continue to grow and spread unless controlled. Moreover the large size of mature Bilberry Cactus plants is likely to have a negative effect on the small endemic succulents that share the same host plants.

Description of two new Obriini Mulsant, 1839 (Coleoptera: Cerambycidae) from the Tankwa Karoo biome in South Africa and Namibia.

Two new species of Capezoum: C. tankwakarooensis sp. nov. and C. museiconfluentiarum sp. nov. are described from the Succulent Karoo ecosystem in South Africa and Namibia.