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Background & Research Aims: Understanding how people and wildlife coexist is crucial to informing conservation and management of biodiverse areas, supporting both wildlife conservation and human well-being. Yet, most studies of human-wildlife conflict and coexistence focus on a limited number of wildlife species. Methods: This study characterizes patterns of reported human-wildlife conflict in the Okavango region of Botswana based on records for all species from the Botswana Department of Wildlife and National Parks (2008 – 2016). Results: The reported incidents implicated a diverse range of wildlife species in conflict. The patterns indicated that for conflicts like crop and property damage, only a few main species were implicated, while livestock damage reports had more diversity of conflict species. Additionally, people in this region faced wildlife challenges throughout the year. Conclusion & Implications for Conservation: Having such variable types and timing of conflict, and from diverse species, may make it particularly difficult for people to mitigate costs and prevent further conflicts. [ABSTRACT FROM AUTHOR]

Where wetlands transcend country borders, cooperation is key for their management, comparable with transboundary rivers and lakes. Building on existing research on rivers, lakes and groundwater, this paper uses document analysis and interviews to understand how countries work together on transboundary wetlands. First, indicators of cooperation are identified based on the water diplomacy literature. These are then applied to three wetlands, finding strong evidence of cooperation in the Wadden Sea, moderate evidence in the Okavango Delta and no evidence in the Hamoun Wetlands. Wetland cooperation seems highest where it is institutionalized. [ABSTRACT FROM AUTHOR]

The Angolan Highlands region includes the Angolan miombo woodland ecoregion which supports miombo woodland, grasslands, subsistence agricultural land, and peatland deposits. Extensive fires, slash and burn agriculture, peat fuel extraction, and peatland drainage are among the anthropogenic practices that threaten these peatland deposits. Peat fires cause peatland degradation, release significant amounts of greenhouse gases, deteriorate air quality, and contribute towards climate change and biodiversity loss. This study presents an analysis of the fire regimes over the period 2001 to 2020 in an under-studied area of the Angolan Highlands. Moderate Resolution Imaging Spectroradiometer (MODIS) fire and vegetation data were used in combination with a land use/land cover (LULC) classification map to calculate fire frequency, burn area, and fire regimes. The fire patterns within the study site are comparable to those found in African woodland savannas. Across the study site, 6976 km2 (11.31%) of the land surface area burned at least nine times from 2001 to 2020, occurring largely within in the river valley environment. Considering the different LULC classes, peatlands were calculated to (a) burn more frequently (average fire frequency from 2001 to 2020 = 9.12), (b) have the smallest proportion (4.11%) of area which remained unburnt over the fire archive, and (c) have the largest average proportion (45.65% or 746 km2) of burnt area per year. Peatland burning occurred predominantly during drier months from May to September. The results of this study highlight the strong influence of LULC on the fire frequency and distribution in the study area, requiring unique fire management strategies. As has been documented for boreal and tropical peatlands across the globe, we stress the importance of peatland conservation and protection; continued unsustainable management practices may lead to the loss of these important peatland deposits. [ABSTRACT FROM AUTHOR]

Chonopeltis lisikili Van As and Van As, 1996 was original described from the Eastern Caprivi (Namibia) and the Okavango System (Botswana), collected from five Synodontis Cuvier, 1816 (Mochokidae) species. This fish genus is endemic to Africa, with 130 valid species, making it one of the most species-rich and widely distributed mochokid catfish family. During parasitological surveys conducted in the Phongolo River (South Africa), a Chonopeltis Thiele, 1900 species was collected from Synodontis zambezensis Peters, 1852. In total, 21 adult females, four adult males, as well as representatives of the larval developmental stages were found. After morphological comparison, this branchiuran was identified as C. lisikili. This paper provides additional information on body measurements and morphological information of all the life stages of the Phongolo material. Information on Chonopeltis material collected from the Okavango River, Botswana, not yet published is also included as well as the first molecular characterisation of a Chonopeltis species using COI and 18 S rRNA partial sequencing. The endemicity of the host and fish lice necessitates a discussion on the host origin and distribution in more than one river system, particularly referring to host specificity for Chonopeltis species.

Okavango River Bridge in Botswana, Africa – elephant tusks for the Okavango The Okavango River in Botswana, Africa, flows into an inland delta. The resulting fertile areas are the basis for the unique richness of flora and fauna – a point of attraction for tourists from all over the world. To facilitate access to the northeastern part of the delta, it was decided to replace the existing ferry connection with a fixed bridge connection as a cable‐stayed bridge. To emphasize the symbolic character of the structure, the towers were designed in a special design idea as A‐towers in the shape of crossing elephant tusks. This article describes the design history as well as the implementation of the special proposal of the execution with its important details. Construction has been underway on site since 2018, with the ceremonial opening and traffic clearance taking place at approximately the same time as the publication of this journal issue. The structure will make a significant contribution to the improvement and development of the infrastructure of the Okavango Delta. [ABSTRACT FROM AUTHOR]

Inland fisheries play a critical role in the ecology of the Okavango Delta, but their conservation is particularly complex. For nearly a decade, communities, conservancies, policy makers, and partner organisations have worked to establish fish reserves across the Kavango and Zambezi. Guidelines on the establishment of fish reserves have been developed to delineate the process through which these protected areas are established, and a structured learning process has unpacked knowledge held by different stakeholders to better understand the opportunities and limitations of fish reserves and to subsequently revise these guidelines. This article aims to share these lessons and to contribute to the debate on the most effective institutional arrangements for this unique space of conservation. [ABSTRACT FROM AUTHOR]

Abstract The Okavango Delta in northern Botswana is an endorheic ecosystem formed by 150,000 islands surrounded by a flood plain. The vegetation of these islands displays an external tree ring enclosing a barren interior domain with evaporitic deposits. We sampled the groundwater into piezometers across an island at the southwest of the Delta, and drilled sediments. The geochemical analysis of the water exhibits two different compositions: a fresh water in the floodplain and a saline water in the interior part. These inner samples display enrichments in heavy metals, metalloids and critical metals such as, Rare Earth Elements (REE). The latest show a continuous enrichment from LREE to HREE and positive Ce and Eu anomalies, associated to alkaline pH. Overall, the two types of displayed REE patterns fingerprint two different water sources. The geochemistry of sediments indicates the same composition whatever the sample location and no traces of evaporitic deposits was found. The variations in the water table depth in the piezometers shows different hydrological behaviors in between the floodplain and the barren zone which does not follow the flood cycle. Thus, we document two different aquifers with independent hydrological behaviors: a surface fresh‐water aquifer in the floodplain connected to the channels, and a saline confined aquifer below the islands. The contrasted geochemical composition of the waters explains the distribution of the vegetation which survives through access to fresh water. The hydrological architecture of this island in the southwestern Delta differs from other islands, highlighting the hydrological complexity of the Okavango Delta.

The Okavango Delta in northern Botswana is an endorheic ecosystem formed by 150,000 islands surrounded by a flood plain. The vegetation of these islands displays an external tree ring enclosing a barren interior domain with evaporitic deposits. We sampled the groundwater into piezometers across an island at the southwest of the Delta, and drilled sediments. The geochemical analysis of the water exhibits two different compositions: a fresh water in the floodplain and a saline water in the interior part. These inner samples display enrichments in heavy metals, metalloids and critical metals such as, Rare Earth Elements (REE). The latest show a continuous enrichment from LREE to HREE and positive Ce and Eu anomalies, associated to alkaline pH. Overall, the two types of displayed REE patterns fingerprint two different water sources. The geochemistry of sediments indicates the same composition whatever the sample location and no traces of evaporitic deposits was found. The variations in the water table depth in the piezometers shows different hydrological behaviors in between the floodplain and the barren zone which does not follow the flood cycle. Thus, we document two different aquifers with independent hydrological behaviors: a surface fresh‐water aquifer in the floodplain connected to the channels, and a saline confined aquifer below the islands. The contrasted geochemical composition of the waters explains the distribution of the vegetation which survives through access to fresh water. The hydrological architecture of this island in the southwestern Delta differs from other islands, highlighting the hydrological complexity of the Okavango Delta. Plain Language Summary: Endorheic basins are hotspots for biodiversity and human activities. The Okavango Delta in northern Botswana is one of the largest wetlands in Africa, and forms a huge oasis in the arid Kalahari Desert. The water flowing from Angola reaches the mega‐alluvial fan confined in between two fault zones, before being absorbed by evaporation and evapotranspiration. The 150,000 islands scattering the wetland are surrounded by an annually flooded alluvial plain. The depth of the water table in the floodplain follows the water level variations in the channels; whereas it remains deeper and nearly constant in the interior part of the island. The chemical analysis of the water samples recovered in piezometers reveals that the deep saline water contains high concentrations of trace elements, whereas the water sampled in the floodplain is fresh with low concentrations in trace element. The chemical quality of the waters and the non‐correlated variations in the water tables through time indicate the occurrence of two independent aquifers: one on the surface with fresh water and a second one at a table depth of 2–3 m with more saline water. This model proposed for the southwestern part of the Delta differs from the hydrochemical system established for islands in the eastern region, highlighting the hydrological complexity of the endoreic ecosystem of Okavango. Key Points: Hydrological data, Rare Earth Elements (REE) patterns and geochemical data reveal different sources of water located in two independent aquifersTwo different types of water with low element concentrations for fresh water in an unconfined aquifer versus highly enriched chemical concentrations in a confined aquifer at depthAlkaline groundwater inside island displaying REE patterns exhibiting enrichment from LREE to HREE [ABSTRACT FROM AUTHOR]

Chonopeltis lisikili Van As and Van As, 1996 was original described from the Eastern Caprivi (Namibia) and the Okavango System (Botswana), collected from five Synodontis Cuvier, 1816 (Mochokidae) species. This fish genus is endemic to Africa, with 130 valid species, making it one of the most species-rich and widely distributed mochokid catfish family. During parasitological surveys conducted in the Phongolo River (South Africa), a Chonopeltis Thiele, 1900 species was collected from Synodontis zambezensis Peters, 1852. In total, 21 adult females, four adult males, as well as representatives of the larval developmental stages were found. After morphological comparison, this branchiuran was identified as C. lisikili. This paper provides additional information on body measurements and morphological information of all the life stages of the Phongolo material. Information on Chonopeltis material collected from the Okavango River, Botswana, not yet published is also included as well as the first molecular characterisation of a Chonopeltis species using COI and 18 S rRNA partial sequencing. The endemicity of the host and fish lice necessitates a discussion on the host origin and distribution in more than one river system, particularly referring to host specificity for Chonopeltis species. [Display omitted] • First COI sequence for genus Chonopeltis. • First phylogenetic analysis of Branchiurans using 18 S rRNA. • New host and locality record for Chonopeltis lisikili. • First illustrations of the majority of C. lisikili life stages, in fact for any of the known Chonopeltis species. [ABSTRACT FROM AUTHOR]

Inland fisheries play a critical role in the ecology of the Okavango Delta, but their conservation is particularly complex. For nearly a decade, communities, conservancies, policy makers, and partner organisations have worked to establish fish reserves across the Kavango and Zambezi. Guidelines on the establishment of fish reserves have been developed to delineate the process through which these protected areas are established, and a structured learning process has unpacked knowledge held by different stakeholders to better understand the opportunities and limitations of fish reserves and to subsequently revise these guidelines. This article aims to share these lessons and to contribute to the debate on the most effective institutional arrangements for this unique space of conservation.

Kassinula is a monotypic genus of small frog in the family Hyperoliidae, only represented by Kassinula wittei. This species morphologically resembles both Kassina Girard, 1853 and Afrixalus Laurent, 1944, and its taxonomic status has been debated for decades. It has previously been subsumed within Kassina, and is currently placed as a sister genus to Afrixalus, although it has not been included in any phylogenetic studies until now. This species is poorly represented in museum collections and is only known from fewer than 35 specimens from southern Democratic Republic of the Congo and adjacent Zambia. Newly collected material from central Angola, a range extension of 400–800 km west of previously known localities, allowed us to revisit the taxonomic placement of the genus with the aid of phylogenetic analysis and shed light on its geographic distribution, morphology and natural history. Although our phylogenetic analysis is limited to a single mitochondrial gene (16S), we place Kassinula in the subfamily Hyperoliinae and closely related to Afrixalus, with a high degree of confidence. Further phylogenetic studies are needed before formally synonymising Afrixalus with Kassinula. [ABSTRACT FROM AUTHOR]

Reports of a mass die-off of ~350 elephants ( Loxodonta africana) in northern Botswana over a period of two months (May-June 2020), has fuelled speculation and concern regarding the cause. Although the area in which these mortalities occurred is not protected and is considered a hotspot for human--elephant conflict and poaching, both malicious poisoning and poaching are unlikely to have played a role as other species were not affected, and elephant carcasses were found with tusks intact. In the absence of a confirmed cause we sought to identify the lines of enquiry that are most likely to lead to a definitive answer. In particular, we consider viral and bacterial agents that could precipitate species-specific mortalities on this scale, potential environmental sources of poisoning and the samples and tests that would assist in excluding/confirming these candidate causes. Whilst it may be argued that these mortalities are unlikely to negatively impact the broader elephant population of ~130 000 individuals in Botswana, the same cannot be said of the many vulnerable population pockets in other parts of Africa. For this reason, it is essential that the cause of the current die-off is identified as it is the only way to prevent similar losses of susceptible elephants elsewhere. [ABSTRACT FROM AUTHOR]

Vector mosquitoes contribute significantly to the global burden of diseases in humans, livestock and wildlife. As such, the spatial distribution and abundance of mosquito species and their surveillance cannot be ignored. Here, we surveyed mosquito species across major tourism hotspots in semi-arid Botswana, including, for the first time, the Central Kalahari Game Reserve. Our results reported several mosquito species across seven genera, belonging to Aedes, Anopheles, Culex, Mansonia, Mimomyia, Coquillettidia and Uranotaenia. These results document a significant species inventory that may inform early warning vector-borne disease control systems and likely help manage the risk of emerging and re-emerging mosquito-borne infections.

Canadian oil and gas company, Reconnaissance Energy Africa (ReconAfrica), plans to exploit potential oil reserves in the Cubango Okavango River Basin (CORB) in Namibia and Botswana, where little is known about the local groundwater systems and how contamination and its effects could impact the region. Using borehole data from target oil and gas areas, we calculated hydraulic gradients, flow direction, and flow velocity to map potential groundwater contamination effects from oil and gas drilling in the region. We also plotted the major geological structures, calculated flowpaths, and estimated travel times for contaminated groundwater that may travel along these preferential flowpaths from the drill sites to the Okavango River and Delta. Results indicate that contaminated groundwater from the oil lease areas could take 3–23.5 years to reach the Okavango River system via the shallow sandy aquifer, but in a worst-case scenario, contamination could reach the Delta within four days via structures associated with dykes and faults that serve as primary flowpaths. Such contamination could adversely affect human health and the region's ecosystems and biodiversity. We recommend prohibiting oil exploration and production activities within the CORB until future studies can determine the impacts of hydrocarbon extraction with greater certainty. • Oil is currently being explored for in the Okavango region. • Oil drilling contaminants could pollute the groundwater in the drilling area. • Current drilling site contamination could reach the Okavango River within 10 years. • Groundwater contamination could have lasting effects on ecosystems and communities. [ABSTRACT FROM AUTHOR]

Climate change is expected to have a major impact on the arid savanna regions of southwestern Africa, such as the Okavango Basin. Precipitation is a major constraint for agriculture in countries like Namibia and Botswana and assessments of future crop growth conditions are in high demand. This GIS-based approach uses reanalysis data and climate model output for two scenarios and compares them to the precipitation requirements of the five most important crops grown in the region: maize, pearl millet, sorghum, cassava and cow pea. It also takes into account the dominant soil types, as plant growth is also limited by nutrient-poor soils with unfavorable physical and chemical properties. The two factors are then combined using a fuzzy logic algorithm. The assessment visualizes the expected shifts in suitable zones and identifies areas where farming without irrigation may experience a decline in yields or may even no longer be possible at the end of the 21st century. The results show that pearl millet is the most suitable crop in all scenarios while especially the cultivation of maize, sorghum and cow pea may be affected by a possible reduction of precipitation under the high-emission scenario.

Gnathostomiasis is a zoonotic nematode parasite disease, most commonly acquired by eating raw or undercooked fish. Although the disease is well known in parts of Asia and Central and South America, relatively few cases have been reported from Africa. Raw fish consumed in the Okavango River delta area of Botswana, and in nearby western Zambia, has previously produced laboratory-proven gnathostomiasis in tourists. The purpose of this communication is to record additional cases of the infection acquired in the Okavango delta, and to alert visitors to the inadvisability of eating raw freshwater fish in the southern African region.

Aim: The social-ecological systems of south east Angola currently undergo rapid transformations and at the same time the region is highly understudied. We aim to provide a first comprehensive analysis of vegetation types, their environmental drivers and woody species diversity of the region. Study area: Cubango River Basin in south-east Angola and northern Namibia. Methods: We conducted a plot-based vegetation survey covering all major terrestrial vegetation types. 190 relevés of 1000 m2 were classified based on a numerical classification approach. We used NMDS ordination and data on soils from field sampling, topography, climate and remotely sensed land surface phenology to investigate vegetation-environment relationships. The number of woody species was estimated using four non-parametric species richness estimators and rarefaction curves. Results: We provided a detailed description of the resulting twelve woody plant communities, in terms of species composition, structure, and habitat characteristics. At the scale of the Cubango Basin, differences in the regional climate were the most important drivers of plant species composition. Topsoil properties did not vary much throughout the study area, but higher contents of silt and clay in the lower soil horizons appeared to drive species composition in the miombo woodlands. Furthermore, we demonstrated how the usage of land surface phenology metrics add value to the interpretation of ecological properties of plant communities in providing insights on the timing of the growing season and on different aspects of above-ground biomass. The number of woody species in the entire Cubango Basin was estimated to be 471 (SD=29) species, for the miombo woodlands 302 (SD=11) species, and for the Baikiaea woodlands 262 (SD=20) species. Conclusion: The presented classification scheme and the analysis of environmental drivers of vegetation types provide a solid basis for future investigations of the vegetation of southeast Angola, and will provide important baseline data for conservation planning and sustainable natural resource management. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the influence of distance from surface water on riparian woodland communities in the Okavango Delta. Vegetation sampling was conducted in seven sites within the Okavango Delta in 20 m × 10 m belted plots placed perpendicular to the river bank. The plots were placed at 0-10 m, 10-20 m, 20-30 m, 30-40 m and 40-50 m distance classes increasing away from the river bank. Tree height, basal area, species richness, canopy cover and diversity were determined for each distance class. Indicator species analysis was used to determine the characteristic species at each distance class. Single-factor ANOVA and Tukey post hoc analysis were used to compare species diversity, mean tree height, cover and basal area between distance classes. Correlation between distance from surface water and vegetation parameters was sought using Spearman regression analysis. All parameters except for species richness varied significantly ( P < 0.05) along distance from surface water. Distance from surface water was positively correlated all vegetation parameters except for mean species richness/plot. These results show that distance from surface water influences riparian plant community composition and distribution in the Okavango Delta. This implies that riparian plant species can be indicators of long-term hydrologic conditions in the Delta. [ABSTRACT FROM AUTHOR]

The Okavango Graben (OG) has been considered as the terminus of the southwestern branch of the East African Rift System (EARS) since the 1970s based on fault morphology and early seismic and geophysical data. Thus it has been assumed to be an incipient rifting zone, analogous to the early stage of mature rifts in the EARS. Recent geodetic data and geophysical studies in the area bring new insights into the local crust and lithosphere, mantle activity and fault activity. In this study, we computed the velocities for three permanent GPS stations surrounding the graben and undertook a review of the new geophysical data available for the area. The northern and southern blocks of the graben show an exclusively low strike-slip displacement rate of about 1mm/year, revealing the transtensional nature of this basin. The seismic record of central and southern Africa was found to be instrumentally biased for the events recorded before 2004 and the OG may not represent the most seismically active area in Botswana anymore. Moreover, no significant lithosphere and crustal thinning is found in the tectonic structure nor any strong negative Bouguer anomaly and surface heat flux. Thus the OG does not match the classical model for a rifting zone. We propose a new geodynamic model for the deformation observed west of the EARS based on accommodation of far-field deformation due to the differential extension rates of the EARS and the displacement of the Kalahari craton relative to the Nubian plate. [ABSTRACT FROM AUTHOR]

Cross-border studies offer unique situations to study the impact of different land-use regimes on ecosystems. Along the Angolan and Namibian border formed by the Okavango River, the environmental conditions and traditional land-use practises are the same on either side of the river. However, decades of civil war in Angola led to a stagnant development while political stability in Namibia fostered a recent socio-economic transformation. We investigated the impact of spatially diffuse land use on plant diversity of the dry tropical woodlands covering the vast, sandy hinterlands of the river. As accessibility is the major factor governing land use, we used distance to road as a proxy for land-use intensity. Based on 58 vegetation plots sized 20 m × 50 m, we showed that species richness increased with distance to road in Angola while in Namibia it remained constant on a lower level. Evenness showed an inverse pattern to species richness and Shannon diversity index showed no response. Analysing diversity patterns according to life forms revealed that these patterns are primarily driven by woody species. The study showed that spatially diffuse land use has a measurable effect on plant diversity and illustrates that roads act as vectors of change. [ABSTRACT FROM AUTHOR]

Water is both a key and limited resource in the Okavango Catchment of Southern Africa. It is vital for the ecosystem and the three riparian states Angola, Botswana and Namibia who use the water of the catchment for multiple purposes including pastoralism, farming and tourism. Socioeconomic changes, primarily strong population growth and increasing development demands pose significant challenges for the Okavango Catchment and its Integrated Water Resource Management (IWRM). In this paper, we first review the socioeconomic background and the current and projected water situation. Against this background, we analyze the dependence of the riparian states and the local livelihoods on the Okavango Catchment. Third, we discuss the implications of socioeconomic changes and increased water demand for the IWRM in the catchment. We review the scientific literature and relevant reports. Further we utilize (geo-spatial) analysis of socioeconomic, livelihood and hydrological data, supplemented by a field visit to Namibia and Botswana. Our findings suggest that strong population growth and the stabilization of Angola are likely to increase the pressure to develop the region along the Okavango. The central challenge for IWRM is hence to enable Angola to meet its development needs without limiting livelihood and economic prospects in Botswana and Namibia.

In the Okavango Delta information on the riparian woodland vegetation community composition and distribution is generally lacking. Past studies in the Delta were mainly focused on the quantitative classification of seasonal floodplain herbaceous vegetation communities. The aim of this study was to determine riparian woodland vegetation communities in the Okavango Delta. Vegetation sampling was conducted in 20 m × 50 m randomly placed plots. The plots were placed along a gradient from the main water body to the drier fringe of the riparian zone. Plant species present in each plot were recorded with their estimated percentage cover using the Braun–Blanquet cover abundance scale. Hierarchical cluster analysis was used to determine vegetation communities. Indicator species analysis was used to calculate indicator values for species groups defined from the cluster analysis. Plant species and diversity were determined for each vegetation cluster. Multi-response permutation procedures (MRPP) were used to determine significance of differences between communities. The Kruskal–Wallis test was used to compare species diversity and richness between vegetation communities. Four vegetation communities were identified:Croton megalobotrys– Hyphaene petersiana,Vachellia erioloba–Diospyros lycioides,Syzygium cordatum–Phoenix reclinataandGarcinia livingstonei–Senegalia nigrescens.In this classification, theSyzygium cordatum–Phoenix reclinataandGarcinia livingstonei–Senegalia nigrescensplant communities are found in frequently flooded regions, whereas theCroton megalobotrys–Hyphaene petersianaandVachellia erioloba–Diospyros lycioidesare in occasionally flooded regions. Total number of species was highest in theGarcinia livingstonei–Senegalia nigrescensand lowest in theSyzygium cordatum–Phoenix reclinatavegetation communities. The MRPP showed that there was significant (p< 0.05) differences between vegetation communities. Species diversity and richness were significantly (p< 0.05) higher in theGarcinia livingstonei–Senegalia nigrescensvegetation community. This study provided an inventory of riparian woodland plant communities, which can be used as a vital monitoring tool of vegetation change in the Okavango Delta. [ABSTRACT FROM AUTHOR]

Dry tropical woodlands are the characteristic natural vegetation type of southeast Angola, where precipitation is seasonal and nutrient content of soils is very low. Subsistence farmers overcome the poor abiotic conditions by using shifting cultivation based on specific site selection. We describe the vegetation composition of a previously unstudied dense woodland tract, which is preferred for agriculture, comparing it to nearby open woodland. We placed 25 vegetation plots randomly in the two types of natural woodland vegetation (open and dense) as well as in fallows with three different durations of land use. In each plot the cover of all vascular plant species was recorded. Variables describing vegetation structure, including basal area and leaf area index, were recorded. We analyzed soil samples for texture, pH, conductivity and nutrients, and investigated the impact of land use duration on woodland regeneration. We found that species composition and vegetation structure of the dense woodland differed greatly from the surrounding open woodland. The dense woodland is preferable for agriculture because of its higher soil content of silt, clay and potassium, higher woody biomass, and more abundant soft litter. A longer duration of land use affects species composition and diversity of the regenerating vegetation as well as nutrient content in the soil. In the near future, the increasing demand for agricultural land is likely to change the structure and composition of the dense woodland. [ABSTRACT FROM AUTHOR]

Atmospheric methane (CH) is one of the three key greenhouse gases (GHGs) driving global climate change. The atmospheric concentration of CH has increased by about 150 % above pre-industrial levels of 400-700 ppb due to anthropogenic activities. Although tropical wetlands account for 50-60 % of the global wetland CH emissions, the biogeochemistry of these wetlands, including controls of CH emissions from the systems, is poorly understood compared to temperate wetlands. This has resulted in large inter-model variations of the magnitude and distribution of CH emission estimates from these tropical wetlands. A recent study in the Okavango Delta, Botswana, estimated diffusive CH flux at 1.8 ± 0.2 Tg year, accounting for 2.8 ± 0.3 % of the total CH emission from tropical wetlands. In this paper we present an assessment of relationships between diffusive CH flux rates and physicochemical variables in the overlying water column to identify and understand regulatory variables for the diffusive CH fluxes in the Delta. The results show that diffusive CH flux rates from the Delta seem to be controlled by a combination of physicochemical variables. Although site specific fluxes seem to be controlled by different combinations of factors, temperature was the primary predictor of CH flux rates at almost all the sampled habitats and sites in the Delta. Most physicochemical variables, especially in the permanent swamps, were correlated with temperature implying that their regulatory effect on diffusive CH fluxes could be modified by climate change feedback as well. [ABSTRACT FROM AUTHOR]

Only a few reports exist on diplostomid metacercariae found in southern African fish and even less information is available on the pathology associated with these infections. During surveys conducted in December 2008 and August 2010, different fish species were collected from the Okavango (Botswana) and Orange–Vaal (South Africa) River Systems. Histological sections were done from intactTilapia sparrmaniiA. Smith, 1840 andCoptodon rendalli(Boulenger, 1896) eyes and the brains of infectedBrycinus lateralis(Boulenger, 1900) in order to determine the precise site of infection and the possible pathological effects. It was found that the encapsulated diplostomids from the eyes of the infected haplotilapiine species from the Okavango System caused localised retinal and/or choroid detachments. No pathological effects were observed in the histological sections of the brains ofB. lateralisthat were infected with diplostomids, except for the presence of red blood or rodlet cells.Tilapia sparrmaniicollected from the Orange River were not infected with diplostomids. [ABSTRACT FROM PUBLISHER]

The complex life cycles of most trematode parasites include three hosts. The first intermediate host is a snail, the second is normally a teleost fish and a piscivorous bird serves as the definitive host. Lymnaeid snails are most likely to be responsible for cercarial shedding, which infect exposed fish and in turn are eaten by piscivorous birds. From 2008 to 2010 fish in the Okavango and Orange-Vaal River Systems were collected and dissected in order to determine the prevalence and intensity of larval trematode infections in the eyes and brains. This paper discusses the possible ecological factors which can influence the probability of certain fish species becoming infected with diplostomid cercariae and hence metacercariae. The feeding strategies and sizes of piscivorous birds, which could act as definitive hosts for the adult worms, are summarized and discussed. Information on the snail species responsible for furcocercous cercarial shedding in the two study sites is also included. [ABSTRACT FROM AUTHOR]

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Highlights: [•] We assess role of anthropogenic climate change in recent floods in the Okavango basin. [•] Hydrological model is forced with simulated current and pre-industrial climates. [•] Anthropogenic climate change has reduced probability of high floods in the Okavango. [•] Reduction is due to increased evaporation; rainfall changes are minor. [Copyright &y& Elsevier]

The Okavango River system flows through Angola, Namibia and Botswana. It is in near-natural condition and supports globally iconic wetlands and wildlife. The basin’s people are poor and development is inevitable: the next decade is critical. The river could become an example of responsible planning that resolutely addresses the three pillars of sustainable development. Recognizing this, the Member States completed a transboundary diagnostic analysis (TDA) in 2010 funded by the three governments and the Global Environment Facility. A central feature of the TDA was a basin-wide environmental flow assessment using the DRIFT (Downstream Response to Imposed Flow Transformation) holistic approach. This produced scenarios of increasing water resource use that spelled out the costs and benefits in terms of the health of the river ecosystem, associated social structures and local and national economies. The results were used to help create a transboundary strategic action programme, which the Member States are now beginning to act on. This article describes the DRIFT application, the findings and how these could be used to help achieve sustainable development.Editor D. Koutsoyiannis; Guest editor M. AcremanCitation King, J., Beuster, H., Brown, C., and Joubert, A., 2014. Pro-active management: the role of environmental flows in transboundary cooperative planning for the Okavango River system. Hydrological Sciences Journal, 59 (3–4), 786–800. [ABSTRACT FROM PUBLISHER]

We conducted herbaceous and woody vegetation surveys across Botswana's southern Okavango Buffalo Fence, which separates wildlife management from tribal grazing areas, to determine whether the restriction of herbivore movement by fencing has influenced vegetation composition, diversity and structure. We sampled herbaceous and woody vegetation at twenty paired sites every 2 km along the fence. For the herbaceous layer, ten 0.25 m2 quadrats were laid every 10 m perpendicular to the fence; while for the woody vegetation, variable quadrat plots were used. Paired t-tests were run. Results show little difference in forb or grass composition between the two sides. However, the cover and diversity of many woody species were greatly reduced across most height classes on the wildlife management side. Overall woody cover on the wildlife side of the fence was nearly half that of the tribal grazing side ( t = 2.83, P = 0.011, df = 19), while overall wood diversity was also significantly less on the wildlife side ( t = 3.29, P = 0.004, df = 19). We conclude that the concentration of wildlife due to the fence, while improving habitat for some herbivore species, is having a detrimental effect on plant diversity in general. [ABSTRACT FROM AUTHOR]

The Angolan Highlands region includes the Angolan miombo woodland ecoregion which supports miombo woodland, grasslands, subsistence agricultural land, and peatland deposits. Extensive fires, slash and burn agriculture, peat fuel extraction, and peatland drainage are among the anthropogenic practices that threaten these peatland deposits. Peat fires cause peatland degradation, release significant amounts of greenhouse gases, deteriorate air quality, and contribute towards climate change and biodiversity loss. This study presents an analysis of the fire regimes over the period 2001 to 2020 in an under-studied area of the Angolan Highlands. Moderate Resolution Imaging Spectroradiometer (MODIS) fire and vegetation data were used in combination with a land use/land cover (LULC) classification map to calculate fire frequency, burn area, and fire regimes. The fire patterns within the study site are comparable to those found in African woodland savannas. Across the study site, 6976 km 2 (11.31%) of the land surface area burned at least nine times from 2001 to 2020, occurring largely within in the river valley environment. Considering the different LULC classes, peatlands were calculated to (a) burn more frequently (average fire frequency from 2001 to 2020 = 9.12), (b) have the smallest proportion (4.11%) of area which remained unburnt over the fire archive, and (c) have the largest average proportion (45.65% or 746 km 2 ) of burnt area per year. Peatland burning occurred predominantly during drier months from May to September. The results of this study highlight the strong influence of LULC on the fire frequency and distribution in the study area, requiring unique fire management strategies. As has been documented for boreal and tropical peatlands across the globe, we stress the importance of peatland conservation and protection; continued unsustainable management practices may lead to the loss of these important peatland deposits., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this article it becomes evident that the boundaries of Southwest Africa and especially the Northern and Caprivi boundaries are arbitrary and artificial. Human decision-making, although many years ago, created this unnatural situation whereby people speaking the same language and often engaging in the same economic activities, were separated from each other. Separations where economical, ethnic and linguistic factors are not taken into account, occur worldwide and is not a problem restricted to the boundaries of Africa.

When the availability of a vital resource varies between times of overabundance and extreme scarcity, management regimes must manifest flexibility and authority to adapt while maintaining legitimacy. Unfortunately, the need for adaptability often conflicts with the desire for certainty in legal and regulatory regimes, and laws that fail to account for variability often result in conflict when the inevitable disturbance occurs. Additional keys to resilience are collaboration among physical scientists, political actors, local leaders, and other stakeholders, and, when the commons is shared among sovereign states, collaboration between and among institutions with authority to act at different scales or with respect to different aspects of an ecological system. At the scale of transboundary river basins, where treaties govern water utilization, particular treaty mechanisms can reduce conflict potential by fostering collaboration and accounting for change. One necessary element is a mechanism for coordination and collaboration at the scale of the basin. This could be satisfied by mechanisms ranging from informal networks to the establishment of an international commission to jointly manage water, but a mechanism for collaboration at the basin scale alone does not ensure sound water management. To better guide resource management, study of applied resilience theory has revealed a number of management practices that are integral for adaptive governance. Here, we describe key resilience principles for treaty design and adaptive governance and then apply the principles to a case study of one transboundary basin where the need and willingness to manage collaboratively and iteratively is high--the Okavango River Basin of southwest Africa. This descriptive and applied approach should be particularly instructive for treaty negotiators, transboundary resource managers, and should aid program developers. [ABSTRACT FROM AUTHOR]

Environmental change such as variability in water availability, extreme events like floods and droughts, or water pollution pose a serious challenge to the effective management of internationally shared water resources. River basin organizations (RBOs) play an important role in addressing such challenges, developing responses and building resilience. The purpose of this paper is to investigate the ability of RBOs to respond to changes by identifying institutional mechanisms and management practices that have been established by the respective institutions to react to transformations in the basins’ environment. Drawing on the literature of neo-institutionalism and hydropolitics, an analytical framework is developed that includes the following potential determinants for adaptive capacity: membership structure, functional scope, decision-making mechanisms, data and information sharing, dispute-resolution mechanisms, finances and donor support. Subsequently, the framework is applied to two case studies, the Okavango and the Mekong Basin. It is found that the inclusion of adaptation mechanisms contributes to ensuring river basins’ resilience to environmental change while the lack of RBO-internal adaptation mechanisms can hamper resilience and threaten sustainable development. Among these, the membership structure, functional scope as well as data and information-sharing mechanisms are particularly important for building the basis for long-term resilience to change. [ABSTRACT FROM AUTHOR]

Abstract: The Middle Kalahari is characterised by significant regional scale geomorphic activity and landscape change during the late Quaternary period. Very little however, is known about vegetation dynamics over this period due in part to the absence of well-preserved organic records. Here we test the application of phytolith analyses to sandy shoreline deposits of megalake Makgadikgadi, one of the sumps of the Okavango delta, routinely sampled and dated as part of a separate systematic geomorphological analysis. We confirm the presence of both an abundant and diverse assemblage of diagnostic phytoliths within these sand-dominated samples. The phytolith record reveals significant differences in the savanna vegetation through time with the composition of shoreline vegetation during different lake high-stand events was found to vary. Lake high stands are characterised by a coherently grassland dominated signal as well as a general trend towards more mesic and C3 prominent taxa during lake events after ∼40 ka. We suggest that phytolith analyses, whilst far from a perfect proxy, provide the potential to offer an important insight into long-term changes in Kalahari savanna, critical for understanding the response of regional vegetation to climatic and hydrological change both in the past and under future climate change scenarios. [Copyright &y& Elsevier]

1. Little is known about hydrological influences on tropical waterbird communities. We used a 16-year data set (1991-2007) of waterbird censuses, together with a classification of observed species into foraging guilds, to explore the relationships between natural variations in flow regime, foraging guild and the community composition of waterbirds at the Okavango River in the Caprivi Strip of north-eastern Namibia, southern Africa. 2. We addressed three hypotheses to explain variation in waterbird community composition: (i) exploitation (birds move towards resource-rich patches to exploit periods of high food abundance); (ii) escapism (declines in regional habitat quality force birds to aggregate in perennial waterbodies); and (iii) interaction (bird assemblages are dominated by intra- and interspecific interactions, such as flock formation for breeding or moulting, that can be explained better by life history demands or competition than by resource availability). 3. Waterbirds in different foraging guilds responded strongly but at different periods to changes in the hydrological environment, creating a complex but predictable successional pattern in community composition through time. Deep-water feeders responded fastest (abundance peaking 2 months post-flood), followed by shallow-water feeders (4 months) and emergent vegetation feeders (7 months). Species that forage on short vegetation or in mud showed a bimodal response with peaks in abundance at 3 and 8 months post-flood. 4. Our results indicated a strong effect of the local flow regime and hence supported the exploitation hypothesis. The foraging guild approach allowed us to identify clear patterns in a highly complex ecosystem and shows considerable promise as an analytical tool for similar data sets. Our results further suggest that while the entire bird community will be affected by hydrological alterations such as impoundments, water extraction and climate change, deep-water feeders may be one of the most vulnerable groups. [ABSTRACT FROM AUTHOR]

The Okavango Delta is a large, remote, and ecologically significant wetland located in Botswana that receives a strong annual flood pulse. Although the hydrology in flood pulsed systems is often theorized to drive fish population dynamics, in the Okavango Delta there are no monitoring or modeling studies that quantify this complex ecological relationship. The objective of this work was to produce and analyze a mechanistic fish population model of the Okavango Delta that is driven by the annual flood pulse in order to corroborate the theory that Delta fish populations are driven by the flood signal. The model tracked age cohorts over time with density dependant recruitment, mortality, and vulnerability components. Global sensitivity analysis identified the parameters that were the most important in determining the model outcome. Monte Carlo filtering truncated prior parameter probability density functions and refined model uncertainty. One of the unique outcomes of this research was the identification of polishing parameters, i.e. model parameters that are essential in obtaining optimal model performance by matching output variability, though they are not important in changing the magnitude of model results. The flood coefficient (a scaling factor that describes how recruitment changes with the magnitude of the flood) was shown to be a polishing parameter, providing quantitative evidence that floods are a driver of fish population dynamics in the Delta. This linkage between the flood pulse and fish population dynamics provides quantitative information that is necessary for making informed decisions regarding the management of hydrologic and ecological resources in the Okavango Delta. [Copyright &y& Elsevier]

While wildlife is a valuable natural resource with several beneficial values to the people of Kenya and Botswana, wild animals in both countries usually cause damage to society in terms of attacks on people and livestock, damage to crops and other property such as infrastructure, and disruption of peaceful existence in local communities living in close proximity to wildlife areas. Wildlife damage would ordinarily result in people having negative attitudes towards conservation. Interestingly, however, people's perceptions of wildlife in these countries seem to be diametrically different in that whereas public attitudes in Kenya are generally negative, in Botswana they are remarkably positive. This study set out to establish the reasons for this variance in conservation attitudes. It established that the major cause for this variance in perception is that while in Kenya wildlife conservation is more often thought of in terms of wildlife welfare and hardly in terms of human welfare, in Botswana human welfare concerns have been mainstreamed in conservation efforts. People have, for instance, been allowed to derive direct benefits from wildlife through consumptive utilization, unlike in Kenya where only indirect benefits through non-consumptive uses are permitted. These direct benefits seem to mitigate the effects of wildlife damage, especially the resultant negative attitudes of people towards wildlife. The present and future survival of wildlife in many parts of the world, and especially in African countries such as Kenya and Botswana, depends to a large measure on the goodwill of the people, particularly local communities, in their everyday contact with it. [ABSTRACT FROM AUTHOR]

The Okavango wetlands in north western Botswana are the most fire-prone environment in Botswana. Most of these fires are anthropogenic. The fires in this environment are thought to impact the environment negatively and therefore practices that are associated with extensive use of fire have been strongly criticized. Despite this, there has been little work done to understand how these fires impact the wetlands environment and its dynamics, especially the vegetation resources that are used by the local communities in the wetlands. The objective of the study was to identify fire spatial and temporal trends in relation to settlement distribution, through the use of remote sensing, socio-economic and phytosociological surveys. The fire history results show that geographically there has not been any significant change in vegetation structure and that in fact fires may have promoted biodiversity. The results of analysis show an overall variance on vegetation structure of 23% whereas the rest are unaccounted for. There is a strong association between settlements, ethnicities, literacy and fire occurrences. The most fire-prone areas are inhabited by communities that have used fire in the past for various resource use practices. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we have applied discriminant diagrams and bivariate plots for tectonic setting to Quaternary sediments from the East African Rift System (EARS). Sediment samples used in this study represent two different phases in early stage intracontinental rift evolution: the alluvial fan of the nascent Okavango system and a lacustrine basin within the relatively more mature Tanganyika system. The diagrams for tectonic setting for major elements place the majority of these EARS sediments within the passive margin (PM) setting. Passive margin sandstones are generally enriched in SiO2 and depleted in Na2O, CaO and TiO2 reflecting their highly recycled nature. Based on major element discriminant diagrams, we propose two new fields for early stage intracontinental rift evolution (alluvial fan and lacustrine basin), within the previously defined passive margin field. The rare earth element (REE) patterns from both Okavango and Tanganyika sediments exhibit patterns similar to PAAS, with ash layers from the Rungwe volcanics in the Tanganyika samples exhibiting an enrichment in REE relative to the bulk sediment. [Copyright &y& Elsevier]