Browsing by Author "Mlambo, Musa"

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    Biodiversity patterns of wetland macroinvertebrate assemblages in the South-Western Cape, South Africa
    (2009) Mlambo, Musa; Day, Jenny; Reed, Cecile C
    Despite the recent surge in interest in wetland invertebrates, given their immediate importance in overall wetland functioning, these studies have largely been conducted in the northern hemisphere and very little is known in South Africa. In order to fill this knowledge vacuum, this study was conducted to investigate biodiversity patterns of wetland macro invertebrates assemblages in the south-western Cape, South Africa. 140 wetlands were sampled in four geographic clusters, the Cape Flats, the West Coast, the Cederberg and the Agulhas Plain. Open-water, submerged vegetation and emergent vegetation habitats were sampled separately using a square-framed sweep net with a 23.5cm mouth and 80l1m mesh and physico-chemical attributes measured at each site. A total of 126 taxa emanating from more than 26 000 individuals representing 73 genera and 51 families was recorded. Currently, five species new to science were also discovered, three from Hydraenidae (Prosthetops sp. nov, Parhydraena sp. nov and Mesoceration repandum Perkins, 2009), Hydryphantidae (Hydryphanres sp. nov) and Streptocephalidae (Streptocephalus sp. nov). However, all of these new species but one were recorded from single location, suggesting that they might be rare or unique. Richness estimators predicted true taxon richness at about 20-47 taxon more than the observed taxon richness. The high number of uniques and singletons, as well as the Incidence-based Coverage Estimator, suggest that sampling was not adequate to capture the full biodiversity suite. However, I believe this is not necessarily true and this is discussed in detailed in the discussion. The sub-area Cederberg was found to be the biologically richest area, with the three of the new species recorded there. A significant difference was observed in relative abundance (RA) and frequency of occurrence between open-water habitat and vegetated habitats (submerged and emergent vegetation). On the other hand, a significant difference was not found between wetlands with different number of habitat types. No appreciable congruence was seen between different taxonomic groups (i.e. at order and family level) themselves, suggesting that neither can be used as a surrogate for the others. However, predators - which by the way had the highest frequency of occurrence and 2nd highest relative abundance after gatherers - were strongly correlated with overall assemblage and Hemiptera. In addition, together with Hemiptera they had ≥75% similarity with the overall assemblage, suggesting that they are fairly good surrogates for overall assemblage. These results are quite promising especially for biomonitoring programmes and warrant further research. Environmental variables contributed significantly higher in explaining assemblage composition, and the model containing pH, Phosphate, conductivity, turbidity and ammonium was found to explain significant variation in macro invertebrate assemblage.
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    Resurrection ecology of invertebrates in temporary wetlands in the Cape Floristic region: effects of urbanisation and fire
    (2017) Blanckenberg, Michelle; Mlambo, Musa; Reed, Cecile C
    Despite their importance to regional biodiversity, temporary wetlands and their invertebrate communities are generally understudied and under-conserved. Resurrection ecology is used to study the communities present in the dry phase of temporary wetlands to gain a better understanding of the functioning and health of these systems. The hatching success of invertebrate propagules in dried soil sediments, collected from temporary wetlands in Cape Sand Fynbos regions of Cape Town, were investigated in 2016. Soil samples were collected from conserved and urban sites (during May and June 2016) using a standard soil auger method and complemented with monthly aquatic phase sampling using standard sweep net methods (during September and October 2016). The effects of fire were tested, on hatching success by staging vegetation fires over the collected soil samples for five temporary wetland areas in the same region. Mann-Whitney U tests were used to test differences in abundances between treatments, whereas for comparison of taxon richness, Shannon diversity and Pielou's evenness linear mixed effect models (LMER) were used. Non-metric multidimensional scaling (nMDS) plots were used to graphically visualize the community composition between the different treatments, with 'adonis' analysis used to test their statistical significance. Results found a total of 18 invertebrate taxa hatched, while a total of 27 taxa were identified from the wet phase. Results from hatching assays showed no significant differences in diversity patterns of invertebrates between conserved and urban areas in the dry phase. However, wetlands that were in the conserved area supported higher invertebrate diversity during the wet phase, although not significant (lmer, Z = -1.75, p = 0.08). These results suggest that human activity (alien vegetation, littering and polluting) in the area did not impact the ability of invertebrate propagules to emerge, but did slightly affect the natural aquatic phase. Fire had a significantly negative impact on invertebrate diversity measures (lmer, p < 0.001) and community composition (adonis, F = 24.494, p = 0.001) during hatching assays. Management of unpredicted and uncontrolled fire in urban areas is essential to ensure future protection of critical biodiversity areas created by these temporary wetlands. More research should focus on the impact of increasing fire frequency and intensity on these systems to understand the management challenges in a changing climate.