Musa C. Mlambo

The successful release of captive-bred frogs to the wild can be hampered by uncertainty regarding the selection and state of proposed release sites. The Endangered Pickersgill’s reed frog (Hyperolius pickersgilli) has been captive-bred since 2013, to improve the understanding of its husbandry and ultimately for release to the wild at secure rehabilitated wetlands within the species’ native range in central coastal KwaZulu-Natal, South Africa. To facilitate selection of release sites, a bioblitz was conducted at four wetlands at which H. pickersgilli is present and at one potential release site. Wetlands occupied by H. pickersgilli have a dense and variable vegetation structure, comprising an overstory of tall, relatively broad-leaved emergent plants and an understorey of herbaceous plants. These wetlands have a variety of arthropods from various orders and families that are potential predators or prey. Predatory arthropods were present at all sites. Predatory fish and hetero-cannibalistic amphibians were captured at two sites each. The results of the bioblitz allowed us to ascertain what vegetation structure is suitable for H. pickersgilli, and which potential predatory fish and arthropods may be present at proposed release sites. Analysis of environmental DNA from water and soil samples might assist with the identification of fish, amphibian and some arthropod predators at potential release sites because phenotypic and genetic identifications matched in most cases. However, this was the case for relatively few potential prey species. Release sites for captive-bred H. pickersgilli should have a suitable vegetation structure as determined in this study, relatively few predators, and an abundance of small arthropods as prey, amongst other factors. The presence of certain insect species that are easily identifiable may be useful additional indicators of the suitability of potential release sites.

Background: As global temperatures rise, alpine species at the upper limit of their distribution are at risk of decline and extinction due to shrinking habitats downslope. The alpine (> 2 800 m a.s.l.) biodiversity of the Maloti-Drakensberg is poorly known but may be threatened by climate change. Objectives: Using expert BioBlitzes, we documented species richness and elevational patterns of distribution in 14 plant and animal higher taxa from alpine and upper-montane zones in an unexplored corner of the Maloti-Drakensberg. Methods: Using standardised methods such as Sherman traps, acoustic monitoring, bird timed counts, pitfall traps, sweep nets, aquatic SASS5 kick-nets, timed searches and herbarium collections, we assessed elevational zonation of flowering plant and selected invertebrate and vertebrate diversity in the Witsieshoek Community Conservation Area (WCCA). Results: GBIF records complemented expert BioBlitz data, together enumerating 1 216 plant, vertebrate and invertebrate species along an elevation gradient from 1 760 m to 3 145 m at WCCA. Birds, insects and plants showed concordant beta diversity patterns from BioBlitz and GBIF data: high turnover compared to nestedness in more sedentary insects and plants, and the opposite in more mobile birds (GBIF data not available for bats). Although identifications are ongoing, 17% of species or morphospecies were exclusively recorded in the alpine zone, including 82 species of plants and 92 of animals. Conclusion: Alpine endemics are vulnerable to the ‘escalator to extinction’ process due to climate change. Surveys of under-explored alpine hotspots should be prioritised, drawing on mountain tourism-based citizen science. We advocate an ecotourism- and community-centred, restoration and rewilding approach for this strategic and biodiverse community conservation area.

The burgeoning population growth and landscape developments over the last decades have had a profound effect on natural resources including riverine water quality and quantity. This resulted in increased pollution events, loss of aquatic biodiversity and the introduction of alien invasive species, which cumulatively have transformed freshwater ecosystem structure, processes and functions. Macroinvertebrate-based biomonitoring, like the South African Scoring System version 5 (SASS5), is a fast and effective way to assess water and habitat quality. However, studies reporting long-term biomonitoring are rare in many Global South systems. Also, river health within protected areas is generally regarded better than those outside, with the park potentially offering refugium and ideal conditions for rivers to recover. However, Kruger National Park (KNP) rivers get impacted by mining and domestic sewage upstream, before entering the park, and it is not clear how much remediation happens as the rivers flows downstream within the park. The current study was initiated to investigate the long-term river health status of four major river systems flowing across the iconic KNP, using SASS5 biomonitoring and selected physico-chemical parameters. Our results showed that SASS5 indices showed difference in their sensitive to anthropogenic impacts, both in space and time. Long-term dataset revealed that the ability of the rivers to recover from poor to good quality (and vice versa) was quite rapid, and also some rivers were progressively declining (e.g. Olifants and Crocodile rivers) while others were improving (e.g. Luvuvhu and Sabie rivers). Consequently, SASS5 appeared to be a useful tool in assessing the long-term health of KNP rivers, providing valuable insights into the overall ecological conditions and water quality of these important aquatic ecosystems that will assist in the park water resource management strategies. Further, our results demonstrated high sensitivity and quick response of macroinvertebrates to disturbance, and an improvement potential as the rivers transversed the park.

Rivers are recognized as significant pathways and transportation for microplastics (MPs), an emerging contaminant, to aquatic environments. However, there is limited evidence on how riverine reservoirs influence MPs transport. To fill this gap and provide baseline empirical data and insights to South African context, the current study assessed the seasonal variation in MP densities from sediments collected upstream, within the reservoir, and downstream of the Vondo Reservoir along the Mutshindudi River. We hypothesised that MP densities would be highest within the reservoir, due to the lack of constant flow that would otherwise transport accumulated particles downriver. Additionally, we expected the cool–dry season to be associated with the highest MP densities. As expected, high MP densities were observed within the reservoir (117.38–277.46 particles kg⁻¹ dwt) when compared to the downstream (72.63–141.50 particles kg⁻¹ dwt) and upstream (28.81–91.63 particles kg⁻¹ dwt) sites of the reservoir. The cool–dry season (91.63–277.46 particles kg⁻¹ dwt) exhibited the highest MP densities compared to the hot–wet season (28.81–141.50 particles kg⁻¹ dwt). However, MP densities downstream the reservoir were higher during the hot–wet season (141.50 ± 24.34 particles kg⁻¹ dwt) compared to the cool–dry season (72.63 ± 48.85 particles kg⁻¹ dwt). The most dominant MP particles identified were white, transparent, and black fibres/filaments composed primarily of polypropylene (PP) and polyethylene (PE). This suggests diverse sources of MP particles. No significant correlations were found between water parameters and MP densities across sampling sites and seasons, indicating a widespread and context-independent presence of MPs. These findings contribute to MP studies in freshwater environments and further reinforce the role of sediments as sink for MPs and suggest that riverine reservoirs similar to dams can trap MPs, which may then be remobilized downstream during high-flow periods. Importantly, the results of this study can support local municipalities in implementing targeted plastic pollution mitigation strategies and public awareness campaigns, particularly because the Vondo Reservoir serves as a critical water resource for surrounding communities.

Large branchiopods are considered the flagship group for endorheic temporary wetlands globally. Large branchiopod diversity and water quality were assessed from temporary pans in the Khakhea-Bray transboundary aquifer (KBTA) region, a previously unexplored area in the North West Province, South Africa. Ten freshwater pans and a salt pan were sampled across two seasons (summer and winter) in 2022. Six large branchiopod species were identified across seasons in the temporary pans in KBTA, namely Streptocephalus namibiensis Hamer & Brendonck, 1993, Streptocephalus ovamboensis Barnard, 1924, Branchipodopsis wolfi Daday, 1908, Phallocryptus spinosa (H. Milne Edwards, 1840), Triops sp. and Ozestheria australis (Lovén, 1847). The record of P. spinosa in the salt pan was new for North West Province and South Africa. The current data were combined with previous records, revealing that to date, 13 large branchiopod species have been documented in the North West Province. Triops sp., B. wolfi, and O. australis were recorded in summer and were the most common recorded species, whereas S. ovamboensis was only recorded in winter. Species richness was high in summer as compared to winter. The diversity of large branchiopods was mainly influenced by water temperature and phosphates in summer, sediment sodium influenced the diversity in winter. The study elevates conservation through the documentation of large branchiopods of the Khakhea-Bray transboundary aquifer region but also underscores the urgent need to prioritise the conservation of these highly sensitive ephemeral systems which sustain unique assemblages for arid landscapes across the globe.

Anacaena fosteri sp. nov. is described from a high-altitude bog in the Cederberg, Western Cape Province, South Africa. The new species was collected from temporarily wet algal films over peat and likely lives out of water for much of the year. The habitus, aedeagus, femoral pubescence and habitat of the new species are illustrated, together with details of its ecology.

We combined historical records from the literature (1950–2022) with recent field surveys and mesocosm-hatching assays conducted in 2018–2023 and found a total of thirty-two species of large branchiopods in Northern Cape province of South Africa, the largest absolute species richness reported in any area in southern Africa. This highlights this province as an important hotspot for large branchiopods, with six endemic species. Five new species (two anostracans and three spinicaudatans) described in the past six years from southern Africa were from the province. Moreover, our study identified four new species awaiting formal description, which not only enrich the overall diversity but also contribute significantly to the conservation value and functional roles within ephemeral waterbodies. Two new South Africa and province records, namely Leptestheria calcarata (Wolf in Daday, 1923) and a potentially undescribed species of Phallocryptus Birabén, 1951 were recorded. Based on the IUCN conservation assessment, three species are classified as critically endangered (CR), 14 as least concern (LC), and seven as data deficient (DD). It is now an opportune time to update the assessment given that the previous assessment of large branchiopods in southern Africa was conducted in the early 90s. This large-scale, province-wide study, taken together with historical records aims to contribute to our understanding of large branchiopods in the Northern Cape province of South Africa.

More than half of the world’s rivers dry up periodically, but our understanding of the biological communities in dry riverbeds remains limited. Specifically, the roles of dispersal, environmental filtering and biotic interactions in driving biodiversity in dry rivers are poorly understood. Here, we conduct a large-scale coordinated survey of patterns and drivers of biodiversity in dry riverbeds. We focus on eight major taxa, including microorganisms, invertebrates and plants: Algae, Archaea, Bacteria, Fungi, Protozoa, Arthropods, Nematodes and Streptophyta. We use environmental DNA metabarcoding to assess biodiversity in dry sediments collected over a 1-year period from 84 non-perennial rivers across 19 countries on four continents. Both direct factors, such as nutrient and carbon availability, and indirect factors such as climate influence the local biodiversity of most taxa. Limited resource availability and prolonged dry phases favor oligotrophic microbial taxa. Co-variation among taxa, particularly Bacteria, Fungi, Algae and Protozoa, explain more spatial variation in community composition than dispersal or environmental gradients. This finding suggests that biotic interactions or unmeasured ecological and evolutionary factors may strongly influence communities during dry phases, altering biodiversity responses to global changes.

Relictorygmus Seidel, Minoshima, Arriaga-Varela & Fikáček, 2018, the only known African genus of the hydrophilid subfamily Cylominae, currently includes two lentic species from the far southwestern Cape of South Africa. Here Relictorygmus riparius sp. nov. is described, based on specimens collected from wet moss beside a small mountain stream in the Kamiesberg, Northern Cape Province, South Africa, almost 500 km from previously known taxa and the first lotic member of the genus. The new species is compared with the two previously described Relictorygmus, R. trevornoahi Seidel, Minoshima, Arriaga-Varela & Fikáček, 2018 and R. repentinus (Hebauer, 2002) and notes are provided on its ecology at the type locality. This unexpected find suggests that other cylomines may remain undetected in southern Africa, particularly since they can easily be mistaken for species of the morphologically similar, but distantly related, Coelostoma Brullé, 1835.

Protozantaena gigantea sp. nov. is described, based on specimens collected from residual pools in a drying seasonal river in Namaqualand, Northern Cape Province, South Africa. Morphologically, the new species appears to be related to P. labrata Perkins, 1997 from Namibia and P. birdi Bilton, 2022, from the Great Escarpment in the Eastern Cape Province. At up to 2.0 mm in body length, the new species, whilst small, is by far the largest African Protozantaena Perkins, 1997 known to date. The opportunity is also taken to report a new record for P. birdi in the Eastern Cape Drakensberg.