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A study of the population dynamics, production and potential yield of the sardine Limnothrissa Miodon (Boulenger) in Lake Kariba

- Marshall, Brian Eric

  • Authors: Marshall, Brian Eric
  • Date: 1987
  • Subjects: Fishes Lake Tanganyika sardine
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5191 , http://hdl.handle.net/10962/d1001967
  • Description: The limnology of Lake Kariba, especially those aspects that affect sardine biology, are described. The hydrological regime of the lake is seen as a major influence and may be one of the reasons why the fish are very much smaller in Kariba than they are in Lakes Tanganyika or Kivu. Growth was reassessed and there appeared to be a correlation between rates of growth and limnological parameters. In particular, the fish appeared to grow faster, but smaller, in the man-made lakes and this may be a consequence of food shortages brought about by their hydrological characteristics. Mortality rates were also much higher in Kariba and this tended to support the view that the lake is a relatively unsuitable habitat for the sardines. However, estimates of biomass, expressed in terms of lake volume, contradicted this as they were very similar in both Kariba and Tanganyika. The life history strategy of Limnothrissa in Kariba was therefore to reduce its size and increase its productivity in order to maintain the maximum possible biomass and its very high P/B̄ ratio was probably the means by which this was achieved. In terms of lake volume the predicted yields from the pelagic communities of Kariba and Tanganyika were very similar, equivalent to about 20 000 t annually for Kariba. This is close to the yield predicted by several empirical models and the fishery now appears to be entering a phase where increases in effort will not be matched by increased yields. The mechanisms for controlling effort in the fishery appear to be inadequate and particular concern was expressed about the lack of co-ordination between the Zimbabwean and Zambian fishery authorities in planning the development of this shared resource.
  • Full Text:
  • Date Issued: 1987

She left me behind

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Mummy is a poor woman

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Shine

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Wanted me to be a teacher

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Good night everybody

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Jingo little dog

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Siwelile

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Izinto zomhlaba

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Sanudlala ngomlilo

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Gold metallogeny of Australia

- Rankine, Graham M

  • Authors: Rankine, Graham M
  • Date: 1987
  • Subjects: Gold ores -- Geology -- Australia , Gold mines and mining -- Australia , Gold -- Metallurgy -- Australia
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4928 , http://hdl.handle.net/10962/d1004676
  • Description: The gold metallogeny of Australia is predominantly confined to the Archaean and Palaeozoic Provinces. The Archaean gold occurrences are predominantly hosted in ultramafic-mafic dominated greenstone belts, with less associated tofelsic-volcanic and sedimentary sequences. Most gold occurrences are confined to shear zones or faults, and adjacent discoveries of economic laterite-hosted deposits, host rocks. Recent are presently under investigation and will supply a significant proportion of production in the future. The Proterozoic gold deposits of Australia , are confined to geosyncinal sequences, commonly turbidites (eg: Telfer), with other hydrothermal deposits associated directly to granites. An important feature of the North Australian Craton deposits, is the spatial association of most deposits to granite bodies, although a genetic link has not been established conclusively. The Roxby Downs deposit in South Australia is a unique occurrence of gold in association to copper, uranium and R.E.E. This deposit is tentatively related to intraplate alkaline-magmatism, with further work necessary. The most significant recent discovery of gold mineralization in Australia is in the Drummond Basin in Queensland. This epithermal is tentatively related to mineralization within the Georgetown Inlier. The latter mineralization is Permo-Carboniferous, in a Proterozoic (and possibly Archaean) sequence of schists. It is tentatively suggested that all the gold mineralization in northern Queensland may be related to single tectonic event, a feature which requires further study . Other mineralization in the Phanerozoic includes the turbidite-hosted metamorphogenic deposits of Victoria, the rift related deposits in New South Wales and magmatic related deposits in Queensland. The gold deposits in Australia may in the future be classified in a tectonogeological framework, similiar to the layout of this dissertation, particularly once further data becomes available on recent discoveries.
  • Full Text:
  • Date Issued: 1987

Come on lets dance

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Sanana lwam

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

A comparison of nesting behaviour and prey selection in some Southern African species of Ammophila (Hymenoptera : Sphecidae)

- Weaving, Alan James Shelley

  • Authors: Weaving, Alan James Shelley
  • Date: 1987
  • Subjects: Hymenoptera
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5600 , http://hdl.handle.net/10962/d1002050
  • Description: Nesting behaviour and prey selection was compared in eight species of Ammophila. The frequent sympatry of these species was a central point of interest in the study. Nest siting differed markedly in several species. A. ferrugineipes, A. dolichodera, A. dolichocephala and, probably, A. conifera nested mostly in open habitats, this being regarded as the most common situation for the majority of Ammophila. A. beniniensis was unusual in nesting in well vegetated habitats, A. vulcania doing so amongst small clumps of vegetation in otherwise open habitats. A. insignis nested in vertical banks or old animal burrows and A. braunsi utilised abandoned burrows of other wasps situated in non-friable clay soils. This is the first time such nest siting has been reported for Ammophila and each of these two species is consequently unique. Many aspects of nest construction behaviour, in particular methods of soil waste disposal, sealing of nests and their final coverage, differed interspecifically, in some cases intraspecifically, but often apparently in response to the habitat. With regard to nest provisioning strategies, all species hunted after digging their nests, except A. dolichodera which is the first Afrotropical Ammophila reported to hunt before excavating its nest. This brings the total number of the world's species of Ammophila showing this behaviour to three. This species, A. beniniensis, A. braunsi and A. vulcania provided one caterpillar per nest; the others supplied several, A. insignis being the only mass provisioner. A. ferrugineipes showed a form of progressive provisioning and maintained several nests at a time; it is the only Afrotropical species known so far to do so. Only two extra-limital species have been reported showing similar behaviour. The observed variations in provisioning strategies can most easily be explained in relation to the habitat. Investigation of prey selection showed that there was very little interspecific overlap in the species of caterpillars used for provisioning nests. This was shown to be due mainly to differing hunting habitat preferences. The various overall patterns of nesting behaviour, and variations in the different components within these patterns, were considered most likely to have resulted from allopatric speciation in different types of vegetation, the more advanced patterns arising in open habitats. The frequent occurrence of sympatry appears to be a reflection of a shifting distribution of mosaic patterns of vegetation types and the post-speciation spread of species. This influence of habitat on behaviour and prey selection has emphasised the need for caution in drawing phylogenetic conclusions from ethology. Further, these considerations provide an alternative to competition in attempting to explain the observed behaviour patterns and distribution of these wasps.
  • Full Text:
  • Date Issued: 1987

Children dancing together

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Uyingewele nkosi wamaviyo

- Mdluli, Joseph, Ga-Rankuwa Workshop Participants, Composer Not Specified, Dargie, Dave

Ixesha selisondele

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Hey wena nyana wami mukusudlala

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Title not specified

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

Musan' ukulala

- Monwabisi Gladstone Sabani, Tracey, Andrew T N

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