Habitats In South Africa Research Articles

Spillover effects from invasive Acacia alter the plant-pollinator networks and seed production of native plants.

Invasive flowering plants can disrupt plant-pollinator networks. This is well documented where invasives occur amongst native plants; however, the potential for 'spillover' effects of invasives that form stands in adjacent habitats are less well understood. Here we quantify the impact of two invasive Australian species, Acacia saligna and Acacia longifolia, on the plant-pollinator networks in fynbos habitats in South Africa. We compared networks from replicate 1 ha plots of native vegetation (n = 21) that were subjected to three treatments: (1) at least 400 m from flowering Acacia; (2) adjacent to flowering Acacia, or (3) adjacent to flowering Acacia where all Acacia flowers were manually removed. We found that native flowers adjacent to stands of flowering Acacia received significantly more insect visits, especially from beetles and Apis mellifera capensis, and that visitation was more generalized. We also recorded visitation to, and the seed set of, three native flowering species and found that two received more insect visits, but produced fewer seeds, when adjacent to flowering Acacia. Our research shows that 'spillover' effects of invasive Acacia can lead to significant changes in visitation and seed production of native co-flowering species in neighbouring habitats-a factor to be considered when managing invaded landscapes.

The influence of environmental factors on the historical distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality

Abstract. Schistosomiasis remains the most endemic disease in tropical regions. Transmission rates and prevalence of schistosomiasis in Africa are relatively high compared to other regions. This is mostly associated with the lack of clean water and sanitation as necessities to curbing the spread of the disease. Over 90% of people in sub-Saharan Africa (SSA) are deprived of clean water and sanitation. 60-80% of the children in South African communities are infected. Climate variability plays a role in the distribution of vector-borne diseases by affecting intermediate host reproduction and changing their habitats thereby decreasing or increasing host survival and disease transmission ability. This study aims to determine the influence of environmental factors on the spatial distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality. The use of species distribution models (SDMs) to model the intermediate snail hosts habitats in South Africa is uncommon, compared to other African countries. To our knowledge no modelling study has been done in South Africa particularly in the Tshwane Municipality, and this has therefore, paved a way for this study. A systematic literature review was conducted to identify all the important climatic variables that impact on the distribution of bilharzia-transmitting snails. Biomphalaria pfeifferi occurrence data was accessed from the National Freshwater Snails Collection, and the climate data was extracted from the ERA5 website respectively. The principal component analysis was used to reduce the multidimensionality of the dataset, with this framework tool, Pearson's correlations helped identify the variables showing a high correlation with the snail datasets and these were included in the ecological niche model. The following climatic variables: temperature, rainfall, water temperature, and other climate-related phenomena such as droughts and flooding influence the distribution patterns of intermediate snail hosts. The model showed high species presence along the central parts of Tshwane, mostly in the following areas Roodeplaat, Mamelodi, Winterveldt, and Refilwe. However, the south-eastern parts of the municipality did not indicate any species occurrence. The findings confirm that environmental factors impact on the historical distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality. The response curves from the MaxEnt model depict the relationship between habitat suitability and environmental factors.

Testing the concept of edaphism for the quartz island flora of the Knersvlakte, South Africa

• Plant-functional traits are useful to study floras on unusual soils. • Quartz island flora, traits and environment differ from the surrounding. • Taxonomic, functional and edaphic diversity are high on quartz islands. • The flora of unusual edaphic habitats is worthy of particular protection. Edaphically unusual sites harbor a flora that is often unique in its taxonomic as well as functional composition and contain many endemic species. While this edaphic endemism, edaphism, has been discussed previously on various special soils, in this study we relate it for the first time to the floristic characteristics of so called “quartz islands”, edaphically driven special habitats in South Africa, and their surroundings (matrix habitat). We sampled the vegetation and soil for 245 vegetation plots in the Knersvlakte Nature Reserve and examined 336 plant species with respect to their evolutionary (plant family, habitat specificity), biogeographical (distributional range) as well as functional traits (life form, leaf succulence, flowering onset, dispersal mode). Based on the floristic uniqueness of the quartz islands, we expect them to host a highly specialized and locally endemic flora with smaller life forms, pronounced leaf succulence (both indicative of resource-conservative economics) and distinct reproductive traits than their surroundings. We find that, compared to the matrix habitat, quartz islands have significantly higher salinity and lower soil pH, and show higher proportion of leaf-succulent species of smaller life forms – some of which are restricted to quartz islands and have different timing of flowering onset, while dispersal via zoochory is less important. Like other special soils, quartz islands harbor unique plant species, which are distinguished by distinct trait patterns. We conclude that the concept of edaphism can be applied to quartz islands.

Modelling potential habitat suitability for critically endangered Arabian leopards (Panthera pardus nimr) across their historical range in Saudi Arabia

Camera trapping can detect and monitor rare species in landscapes spanning thousands of square kilometres but placement of cameras in areas where the animals most likely occur will increase detection success. This vital information is lacking for the critically endangered Arabian leopard (Panthera pardus nimr) that has undergone a 90% decline across its range in Saudi Arabia. We aimed to identify suitable Arabian leopard habitat and potential population capacity in Saudi Arabia using data from leopards living in ecologically analogous habitat in South Africa and Oman. We developed a resource selection function (RSF) from 14 leopards’ GPS data in the Cederberg, South Africa, and validated the model using three leopards in the Little Karoo, and two Arabian leopards in Oman. We then projected the model to the historical range of Arabian leopards in Saudi Arabia to estimate likely leopard locations and potential population sizes based on home range metrics. The RSF successfully discriminated between used and available locations (specificity = 96.7%) and had high predictive ability (Rho > 0.9). Leopards selectively used areas away from human settlements and roads, with high enhanced vegetation index, and intermediate slopes and elevations. Saudi Arabia could theoretically host 4 distinct populations totalling 162–362 Arabian leopard females, depending on home range size. Camera traps deployed in the south-western mountains of Saudi Arabia may be most likely to detect remnant populations of Arabian leopards. Further research is needed into the local abundance of prey species and human activity to ensure the persistence of suitable leopard ranges and inform conservation actions.

Similarity in ixodid tick communities harboured by wildlife and livestock in the Albany Thicket Biome of South Africa.

South Africa has a diverse fauna of ixodid tick species, several of which are of medical or veterinary importance. Elucidation of which host or environmental characteristics determine the composition and abundance of tick assemblages is, therefore, highly relevant to disease management and wildlife conservation efforts. Here, we analysed the similarity in ixodid tick assemblages of three wildlife and three livestock species in a natural (Great Fish River Reserve) and anthropogenic (an adjacent farm) habitat in South Africa. We compared tick infracommunities of three wild host species between the reserve and the farm; of three wild host species within the reserve and of wild and livestock species on the farm (considering body size). Hosts examined in this study harboured the adults and immature stages of 11 tick species belonging to five ixodid genera. Notably, several tick species of South African wildlife have successfully made the switch to livestock and thus both wild hosts and livestock now contribute to the pool of maintenance hosts for these ticks as well as their associated pathogens. This is an important consideration when translocating wildlife or livestock as part of farming or conservation activities.

Surveys of Afrotemperate forests yields two new freshwater crabs (Decapoda: Potamonautidae: Potamonautes MacLeay, 1838) from South Africa

Sampling of remote inland aquatic habitats in South Africa has constantly been yielding novel endemic freshwater crab species (Potamonautes MacLeay,1838). During the present study, we report on the discovery and description of two new freshwater crab species (Potamonautes baziya sp. nov., and P. mariepskoppie sp. nov.) from Afrotemperate forested mountain regions in the Eastern Cape and Mpumalanga provinces of South Africa, respectively. Phylogenetic evidence derived from DNA sequence data of three partial mitochondrial loci (12S rRNA, 16S rRNA and cytochrome oxidase subunit one, COI) corroborates the evolutionary distinction of the two novel species. In addition, morphological and ecological data for the two new species further delineate their evolutionary distinction from congeneric sister species. A comparison of the taxonomically important gonopods 1 and 2 and carapace features among the sister species and other known freshwater crabs of South Africa was further used to provide evidence for the distinction of the two novel species. The discovery of two new species suggest that remote mountainous areas or unsampled regions in South Africa likely harbor several novel species, reiterating a call to document aquatic inland biodiversity in forested and mountainous regions of the country.

First record of pyrrolizidine alkaloids in the southern African biotype of Chromolaena odorata (Asteraceae)

Pyrrolizidine alkaloids (PAs) are amino alcohols, often esterified with mono- or dicarboxylic acids, found in several plant families, including the Asteraceae. Pyrrolizidine alkaloids are used for plant defence against generalist invertebrate herbivores. However, specialist herbivores that are able to sequester PAs from the host plant species derive a number of benefits from these defence compounds. This study investigated alkaloids and PAs from the leaves and roots of the southern African biotype (SAB) of Chromolaena odorata in different regions and habitats in South Africa, with and without the specialist herbivore Pareuchaetes insulata. Alkaloid N-oxides were initially detected in leaf samples by Mayor's and Dragendorff's reagents and later by thin-layer chromatography on root samples with detection by successive treatment with acetic anhydride and Ehrlich's reagent. Two pyrrolizidine alkaloids, rinderine and the stereoisomer intermidine, were isolated from the reduced root extract of the SAB C. odorata and identified by Gas Chromatography-Mass Spectrometry. The structures and configuration of the compounds were confirmed by chemical and spectroscopic methods, especially one-dimensional 1H Nuclear Magnetic Resonance analysis. Pyrrolizidine alkaloids are known to be used by arctiine moths to find their host plant and are sequestered for mating purposes, and furthermore, these compounds render these lepidopterans unpalatable to predators. This study is the first to detect the presence of alkaloids and pyrrolizidine alkaloids in the SAB C. odorata.

Life history of the river goby Glossogobius callidus (Teleostei: Gobiidae).

The river goby Glossogobius callidus is native to freshwater and estuarine habitats in South Africa. Individuals [21.1-144.4 mm total length (LT )] were sampled from impoundments in the Sundays River Valley, Eastern Cape, from February 2014 to March 2015. The largest female was 137.2 mm LT , and the largest male was 144.4 mm LT . Length-at-50% maturity was 75.2 ± 2.1 mm LT for males and 76.2 ± 2.0 mm LT for females. Absolute fecundity was 1028.2 ± 131.7 oocytes per fish, and relative fecundity was 50.1 ± 18.1 oocytes per gram. The spawning season extended from October to December. Fish were aged using sectioned sagittal otoliths. The growth zone periodicity was validated using edge analysis. Longevity was more than 7 years for females and more than 6 years for males. Length-at-age was similar for the two sexes and was best described using the von Bertalanffy growth model as Lt = 74.7(1 - e-1.0(t + 0.1) ) mm LT for the entire population. Using the population age structure, the mortality rate was estimated at 1.3 per year.

The diet of spotted-necked otters foraging in trout-stocked waters in Mpumalanga, South Africa

Human-wildlife conflict is likely to increase as urbanisation increases. African clawless otters, Aonyx capensis, and spotted-necked otters, Hydrictis maculicollis, are illegally persecuted for their perceived role in reducing trout in artificially stocked habitats in South Africa. The diet of African clawless otters has been investigated, but little is known about the diet of spotted-necked otters in these habitats. Using stable isotope techniques, we investigated the diet of spotted-necked otters occupying habitats artificially stocked with trout. Stable isotope analyses revealed that the diet of spotted-necked otters included equal proportions of crab and trout followed by frog. Diet was found to vary between, as well as within, individuals suggesting individual dietary plasticity. Temporal variation in foraging areas was evident for some otters. These results suggest that individual animals specialise on trout when available. However, this was not consistent between individuals. The resulting conflict with freshwater fisheries may, therefore, be primarily due to individual animals adapting to diets consisting largely of farmed trout. The extent of spotted-necked otter influence on stocked trout, however, needs further investigation.

Habitat transformation and climate change: Implications for the distribution, population status, and colony extinction of Southern Bald Ibis (Geronticus calvus) in southern Africa

Abstract Habitat transformation and loss is one of the greatest threats currently facing avian species. The cumulative impact of climate change on habitat loss is projected to produce disproportionate risk for endemic high-altitude species. The Southern Bald Ibis (Geronticus calvus) is an endemic high-altitude species found throughout highland grassland habitats in South Africa and Lesotho. The historical distribution has contracted notably and causal factors remain ambiguous. Furthermore, the historical population (1950–1970) was believed to be stable, but recent local surveys suggest colony declines and the current global population status remains largely unquantified. We assessed the current distribution and population status of the species through predictive modeling and trends in historical and recent colony counts across the species’ range. We examined climate and habitat change as potential causal factors contributing to the historical contraction in distribution, and projected the potential impact of future climate change predicted by global circulation models. Our study confirms that Southern Bald Ibis are of conservation concern. The loss of grasslands to expanding woody vegetation through bush encroachment was the most detrimental habitat transformation type associated with decreased colony growth and colony collapse. We recommend maintaining a minimum threshold of 50% or greater intact grassland habitat surrounding colonies to reduce colony extinction risk and promote colony persistence.

A report of the free-living freshwater planktonic copepods from an ephemeral pool in Limpopo Province, South Africa, with the description of Microcyclops raynerae n. sp.

Abstract Ephemeral pools are biologically important habitats for species adapted to survive through a dry phase. Unfortunately, these pools have been neglected in studies. Copepods are essential in aquatic habitats mainly because of their importance in the food web. Currently there are only 34 species reported from freshwater habitats in South Africa. This study was conducted in an ephemeral pool (Limpopo Province, South Africa). Qualitative sampling was done monthly (December 2014 to June 2015) using a plankton net and specimens were studied through a light microscope. Seven species were collected, three from Calanoida and four from Cyclopoida, including a new species, Microcyclops raynerae. Seven species represent quite a high biodiversity of copepods from a single pool when compared with similar studies previously done in South Africa. The report of Tropocyclops confinis constitutes a new geographical record from South Africa while all other collected species are new records from the Limpopo Province.

Two new species of freshwater crabs of the genus Potamonautes MacLeay, 1838 (Decapoda: Brachyura: Potamonautidae) from the forests of KwaZulu-Natal, South Africa

ABSTRACTRecent taxonomic studies of forest habitats in South Africa have revealed the presence of three new species of freshwater crabs, suggesting that decapod diversity within the indigenous forest biome remain poorly documented. Surveys of the freshwater crabs of north eastern KwaZulu-Natal province produced a number of specimens from Ntendeka Wilderness Area (Ngome forest) and Nkandla and Ngoye forests that proved to belong to two new species following morphological and molecular analysis (mtDNA sequencing of three loci, 12S rRNA, 16S rRNA and COI). Two undescribed species, P. ntendekaensis sp. nov. and P. ngoyensis sp. nov. are described. The divergence time estimation of the new phylogeny for eastern and southern African freshwater crabs is discussed to illuminate biogeographic patterning and to understand factors responsible for cladogenesis.

Exploring the microbial communities associated with Botrytis cinerea during berry development in table grape with emphasis on potential biocontrol yeasts

Table grapes harbour a wide diversity of microbes, some of which are potential biocontrol agents that may be responsible for the control of fungal pathogens in the phyllosphere. This study evaluated the diversity of microbial communities associated with naturally present Botrytis cinerea inoculum, with special emphasis on populations of potential biocontrol yeasts during berry development in table grapes. Samples were collected from two agro-ecological habitats in South Africa (Northern Province), characterised by low rainfall (site A) and high rainfall (site B). The phenological development samples included those at full bloom, pea size and mature berry stages. Within the group of yeasts known to be natural antagonists, Aureobasidium, Cryptococcus, Rhodotorula and Sporobolomyces could be cultured, while pathogenic fungal genera from asymptomatic samples included Cladosporium, Alternaria, and Aspergillus. Botrytis cinerea could only be cultured at the harvest stage from symptomatic and asymptomatic berries. Overall, the study showed the highest prevalence of Alternaria (35.6%), Cladosporium (27.2%) and Rhodoturula (21.2%). In conclusion, the study reveals a diverse pathogenic and beneficial naturally-known yeast genera in the presence of B. cinerea. Such information and knowledge can be further explored to manipulate potential antagonistic populations to prevent establishment of pathogenic populations and secure dominance of antagonistic populations at the harvest stage.

Emergomyces africanus in Soil, South Africa.

We detected Emergomyces africanus, a thermally dimorphic fungus that causes an HIV-associated systemic mycosis, by PCR in 18 (30%) of 60 soil samples from a wide range of habitats in South Africa. Direct and indirect culture techniques were unsuccessful. Experimental intraperitoneal inoculation of conidia induced murine disease.

Movements and diving behaviour of inter-nesting leatherback turtles in an oceanographically dynamic habitat in South Africa

Movements and diving behaviour of inter-nesting leatherback turtles in an oceanographically dynamic habitat in South Africa

The application of camera trapping to assess Rallidae species richness within palustrine wetland habitat in South Africa

Wetlands are vital habitats for a variety of organisms and ecosystem services, but the health of these valuable habitats is declining worldwide. The Rallidae species that rely on these habitats are typically elusive, cryptic and difficult to monitor accurately, especially in dense wetland vegetation. To date, invasive survey techniques such as rope dragging have largely been applied in surveying species within these genera. A survey of palustrine wetland habitat using camera traps was implemented to ascertain the efficacy of this non-invasive monitoring technique for surveying elusive wetland avian species. The survey yielded a total of 445 independent sightings across 15 target wetland species, including four Rallidae species. Our results clearly display that camera trapping as a non-invasive survey technique can effectively determine the presence and monitor arguably the most cryptic and elusive of the Rallidae genera within southern Africa. In addition, data sets produced through this survey technique are unique in that robust data are collected incorporating numerous aspects of species biology and behaviour. Our study further demonstrated the ability of camera trapping to produce accurate, reliable and rapid species inventories within palustrine wetland habitats.

The wetland flora of South Africa: Occurrence patterns, frequency and dominance across a diverse landscape

A survey of vascular plant species occurring in various wetland habitats in South Africa has been generated by supplementing the species list from a vegetation survey with a herbarium checklist and this list of wetland species is compared with the overall flora of South Africa. About 18.8% of all the South African species occur in wetlands and about 4.5% of all species are obligate wetland species, in the sense that they will not be found outside of the wetland environment. These fractions are compared with the fractions calculated per family and this indicates which families are over- or underrepresented in the South Africa wetland flora. Most of the families that are well represented in wetlands are in the monocots and particularly in the Poales, but wetlands in the Fynbos Biome are much more phylogenetically diverse. There are four main wetland assemblages that can be defined by their family composition and that are characteristic of specific wetland environments. These can generally be described as the environments that are permanently submerged, the environments that are permanently to intermittently inundated, the environments of inland saline pans and environments on extremely nutrient-poor substrates consisting of coastal sands, quartzites or peat.

Predicting spawning locations and modelling the spatial extent of post hatch areas for fishes in a shallow coastal habitat in South Africa

Predicting spawning locations and modelling the spatial extent of post hatch areas for fishes in a shallow coastal habitat in South Africa

The rise and fall of an invasive estuarine grass

Spartina alterniflora Loisel. is the only known halophyte that is invasive in intertidal salt marsh habitats in South Africa and it poses a considerable threat to the biodiversity of nearby estuaries. First detected in 2004, regular chemical treatment during the growing period from 2013 and adjustments to the recommended herbicide mix has almost completely removed the plant from the Great Brak Estuary. Part of the success of this treatment was due to the small area of infestation (~1ha), which was not difficult to access. In 2009 there were 429 stems per m2 but following herbicide treatment between 2013 and 2015, by November 2015 there were only 149 stems in the entire estuary (mean=8 stems per m2). Above-ground biomass had been reduced by 74% and below-ground biomass by 90%. Native salt marsh vegetation began to grow between the dead S. alterniflora shoots by October 2014 and increased to 95% cover by November 2015. The maximum total invaded area of 10,221m2 in 2011 was reduced to 10m2 by November 2015. Average annual costs for the control of S. alterniflora were ~ZAR 34, 349), or $ 2414. This study is important as it is one of a few examples of a national prospect of eradication of an invasive alien plant. However continuous monitoring is necessary, as this plant has been shown in other countries to regrow after chemical treatment.

A revision of the "African Non-Spiny" Clade of Solanum L. (Solanum sections Afrosolanum Bitter, Benderianum Bitter, Lemurisolanum Bitter, Lyciosolanum Bitter, Macronesiotes Bitter, and Quadrangulare Bitter: Solanaceae).

The African Non-Spiny (ANS) clade contains 14 species of mostly large canopy lianas or scandent shrubs confined to Madagascar (10) and continental Africa (4, with with one species reaching the southern Arabian peninsula). Members of the clade were previously classified in sections Afrosolanum Bitter, Benderianum Bitter, Lemurisolanum Bitter, Macronesiotes Bitter and Quadrangulare Bitter, and were throught to be related to a variety of New World groups. The group is an early-branching lineage of non-spiny solanums and characters shared with other vining New World solanums are homoplastic. The 14 species of the group occupy a wide range of habitats, from wet forests in western Africa to savanna and dry forests of southern Madagascar and dune habitats in South Africa. Many members of the group are highly variable morphologically, and habit can vary between shrub and canopy vine in a single locality. We here review the taxonomic history, morphology, potential relationships and ecology of these species; we provide keys for their identification, descriptions, full synonymy (including designations of lectotypes and neotypes) and nomenclatural notes. Illustrations, distribution maps and preliminary conservation assessments are provided for all species.