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Chiredzi, Zimbabwe

Tuytens K.,Catholic University of Leuven | Vanschoenwinkel B.,Vrije Universiteit Brussel | Clegg B.,Malilangwe Wildlife Reserve | Nhiwatiwa T.,University of Zimbabwe | Brendonck L.,Catholic University of Leuven
Journal of Crustacean Biology | Year: 2015

Southern Africa is recognized as one of the world's diversity hotspots for large branchiopod crustaceans. Nonetheless, many areas including large parts of Zimbabwe remain poorly studied. We report on the diversity of anostracans and notostracans in a tropical and geologically diverse savannah area in SE Zimbabwe. We explored the links between geology, hydroperiod and diversity and distribution patterns of anostracans and notostracans. In a large survey, 160 temporary clay pans distributed over the four major and diverse geological regions were sampled every fortnight. Seven fairy shrimp and one tadpole shrimp species were recorded. Although the study area is characterized by substantial variation in soil geology, we did not find strong effects of geology on the composition of anostracan and notostracan assemblages in pools of different sizes and hydrology. All species occurred in all four geological regions but the abundance of pools without large branchiopods differed between the four investigated regions. © 2015. Published by Brill NV, Leiden.

Dalu T.,University of Zimbabwe | Dalu T.,Rhodes University | Clegg B.,Malilangwe Wildlife Reserve | Nhiwatiwa T.,University of Zimbabwe
Knowledge and Management of Aquatic Ecosystems | Year: 2012

The aim of our study was to investigate macroinvertebrate communities so as to understand factors and processes structuring macroinvertebrate communities in a small reservoir, Malilangwe reservoir over seven months (April to October). Sampling was performed by active sweep netting and searching soil sediments. Water temperature, conductivity, dissolved oxygen, pH, ammonia, nitrogen, phosphorus, chemical oxygen demand and macrophyte cover were determined. In total, forty-two macroinvertebrate families belonging to 10 orders were identified amongst 13 macrophyte species and sediments. Thiaridae and Physidae (Mollusca) were the dominant and most abundant taxa (57.71%) and there were followed by the Hemiptera (27.31%). High indices for sites 1 to 3 for the Simpsons index, the Shannon-Weaver index and evenness were recorded, while low indices were observed for sites 4 to 5, with significant differences being observed among the study site using the Kruskal-Wallis ANOVA test (p < 0.05). Redundancy Analysis revealed that among environmental factors, hydrologically linked parameters such as conductivity, water level and macrophyte cover had the strongest influence on macroinvertebrate distribution. © ONEMA, 2012.

Dalu T.,University of South Africa | Dalu T.,Rhodes University | Nhiwatiwa T.,University of South Africa | Clegg B.,Malilangwe Wildlife Reserve | Barson M.,University of South Africa
Knowledge and Management of Aquatic Ecosystems | Year: 2012

An assessment was carried out on the impact of Lernaea cyprinacea on fish populations ten years after its first outbreak in the Malilangwe reservoir, and Lernaea cyprinacea is currently showing no sign of declining in the reservoir. Eight fish species were examined for ectoparasite prevalence and intensity. The possible relationship between L. cyprinacea infestation and environmental factors were investigated. Two parasite species, L. cyprinacea in Oreochromis mossambiccus, Oreochromis placidus, Oreochromis macrochir, Labeo altivelis and Tilapia rendalli and trematode cysts (Clinostomoides brieni) in Clarias gariepinus were found. Lernaea cyprinacea prevalence was 100% amongst all cichlids but varied for L. altivelis. Parasite intensity increased during the cool, dry season (May to July), with the greatest mean intensity being observed amongst the cichlids. There was a significant relationship between parasite intensity and environmental factors; dissolved oxygen (p < 0.05), temperature (p < 0.001) and pH (p < 0.001). © ONEMA, 2012.

Dalu T.,University of Zimbabwe | Dalu T.,Rhodes University | Thackeray Z.,Environmental Mapping and Surveying | Leuci R.,Environmental Mapping and Surveying | And 4 more authors.
Water SA | Year: 2013

The study provides a 9-month record of Malilangwe Reservoir water chemistry periodicity, for the period between February and October 2011. Malilangwe Reservoir is a small (211 ha), shallow (mean depth 4.54 m) reservoir situated in the south-eastern lowveld of Zimbabwe. The reservoir has not spilled in nearly 11 years, which makes it a unique system as most reservoirs of comparable size spill annually. This is the first bathymetric and limnological study of the reservoir where the morphology and physicochemical quality of the water body were examined. The reservoir was not strongly stratified during the hot-wet and hot-dry season with oxygen depletion of < 2 mg·ℓ-1 DO being observed in the bottom layers (<6 m depth). Nutrient concentrations varied throughout the seasons. The reservoir exhibited marked seasonal fluctuations in water level, which decreased by over 149 cm between February and October. The N:P ratio rose to as high as 10.9 and generally reflected high levels of phosphorus in the reservoir. There were significant differences (p<0.05) in Secchi depth transparency between the study sites. Differences observed in water quality were due to water level fluctuations, with poor water quality conditions being experienced during the hot-dry season and the cool-dry season when water levels were low. The reservoir was classified as being mesotrophic. Therefore, there is a risk of eutrophication, especially since the reservoir is currently merely a sink for nutrients.

Capon S.D.,Stellenbosch University | Leslie A.J.,Stellenbosch University | Clegg B.,Malilangwe Wildlife Reserve
Koedoe | Year: 2013

Populations that are vulnerable to decline are of particular concern to wildlife managers and uncovering the mechanisms responsible for downward trends is a crucial step towards developing future viable populations. The aims of this study were to better understand the mechanisms behind the historic decline of the sable antelope, Hippotragus niger, population at the Malilangwe Wildlife Reserve (MWR), to assess its future viability and to use this analysis to determine key areas of breakdown in population growth and link these to potential limiting factors. VORTEX, a population viability model was used to assess the future viability of the sable antelope population and a sensitivity analysis was applied to identify the key areas of breakdown in growth. The sable population is currently viable, but remains highly vulnerable to changes in adult female survival, a factor which had the greatest influence on overall population fitness. Lion predation, impacting on the adult segment of the population, appeared to be the main factor responsible for the historic decline at the MWR. © 2013. The Authors.

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