Browsing by Author "Scholtz, Rheinhardt"

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    Feeding preferences of Tripneustes gratilla Linnaeus Echinodermata Echinodea and the prospect for sea urchin aquaculture in South Africa
    (2008) Scholtz, Rheinhardt; Bolton, John J; Cyrus, Mark Digby
    Sea urchin aquaculture for human food is a major industry, and there are prospects for the industry in South Africa. Feeding preferences of the sea urchin Tripneustes gratilla were tested by two different methods; a touch-preference test and a 48-hour consumption test. A touchpreference is established when the sea urchins' lantern teeth touched an algal species. The 48-hour consumption test was performed with paired combinations using four species of fresh algae. It was hypothesized that the preferred species would be similar in the touch-preference test and the consumption test. Five algal species were used in the touch-preference test; namely, Ecklonia maxima (kelp), Gigartina polycarpa, Grateloupia capensi, Porphyra capensis, and U/va rigida. Four of these species were used in the paired consumption test; namely, E. maxima, G. polycarpa, P. capensis and U. rigida. We found that E. maxima was most preferred in the touch-test followed by P. capensis and U. rigida. This result did not correlate with our consumption test. Here, U. rigida was significantly most preferred followed by E. maxima. Overall, the result is significant in relation to the prospect of echinoculture in South Africa as Ulva may provide a valuable alternate feed or supplement to this new industry. Due to the increase in time provided for the paired consumption test, we found that the paired consumption test was more conclusive in providing a preference for Tripneustes gratilla. Our results agree with literature which suggests that Tripneustes gratilla is a genera list feeder; however, Tripneustes gratilla shows definite preferences. Ulva spp. has been grown on a number of abalone farms in South Africa. Integrated aquaculture using T. gratilla and U. rigida as a biofilter and alternate feed is a very promising idea for echinoculture in South Africa.
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    Small mammal community structure (Rodentia: Muridae) in Punda Maria, Kruger National Park, South Africa : Causes and consequences
    (2008) Scholtz, Rheinhardt; Midgley, Jeremy J; Keith, Mark
    The population dynamics of small mammal populations in Punda Maria, Kruger National Park, South Africa was investigated with respect to community size and structure, seed predation and dispersal of several trees. Species populations, community structure and habitat attributes were measured at six sites comprising of 3 habitat types (2 sites per habitat); namely Acaciagrassland, North-facing and South-facing sloped sites. Seasonal variation was investigated at the Acacia sites during late summer (April) and winter months (July). Five habitat attributes were measured; percentages of total cover and herbage, plant litter depth (cm), height of dominant vegetation type measured (m) and edaphic condition were recorded at 15 randomly selected traps per site. Almonds (Prunus dulcis), baobabs (Adansonia digitata), mopane (Colophospermum mopane), and Acacia tortilis seeds were used in the predation and dispersal experiment. North- and South-facing sites were dominated by Aethomys sp. while Acacia sites were dominated by Mastomys natalensis. Seed predation was high at the North-facing slopes, with a significant difference in predation on A. tortilis seeds. Seed dispersal activity was low; no , scatter hoarding was identified; only larder hoarding was observed by Aethomys sp. and M. natalensis at North-facing sites and Acacia sites respectively. Trampling by megaherbivore activity impacted vegetation structure and has negatively affected rodent population and ground activity, particularly at the Acacia sites.