Initial investigations into dynamics of mesozooplankton community structure in Algoa Bay, South Africa
- Authors: Dali, Luzuko O'Brian
- Date: 2011
- Subjects: Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5715 , http://hdl.handle.net/10962/d1005401 , Zooplankton -- Research -- Indian Ocean -- South Africa , Phytoplankton -- Research -- Indian Ocean -- South Africa
- Description: As part of a long-term monitoring programme initiated by the South African Environmental Observation Network (SAEON) Elwandle Node, the spatio-temporal dynamics of mesozooplankton (200–2000 μm) community structure in Algoa Bay, on the Eastern Cape coastline of southern Africa, was investigated in summer and winter of 2008. Physical-chemical and biological variables were measured at selected sites in the eastern and western sectors of the Bay. During summer, nutrient rich waters upwelling into the eastern sector of the Bay contributed to significant spatial variation in selected physical-chemical variables. During winter, virtually no significant spatial patterns in the physical-chemical variables were observed (P>0.05 in all cases). For the majority of physical-chemical variables, no significant seasonal patterns in values were detected (P>0.05 in all cases). Notable exceptions were water column stability and water temperatures which were highest during summer, and seston, turbidity and ammonium concentrations which attained the highest values in winter. The striking seasonal pattern observed in the water column stability, coupled with the upwelling event, coincided with a strong seasonal pattern in the total surface and integrated chlorophyll-a concentrations within the Bay. During summer, the total surface phytoplankton biomass ranged from 1.87–3.11 μg.L⁻¹ and the integrated biomass values between 44.6 and 89.1 mg chl-a m⁻². In winter, surface chl-a concentrations ranged from 0.49 to 0.55 μg.L⁻¹ and integrated biomass from 13.5 to 13.8 mg chl-a m⁻². During both seasons, the large microphytoplankton (>20 μm) fraction contributed the most (>80%) to the total phytoplankton biomass suggesting that phytoplankton growth is not nutrient limited within the Bay. The total mesozooplankton abundance and biomass values during summer varied between 10088.92 and 28283.21 ind.m⁻³ and between 76.59 and 161.94 mg.m⁻³, respectively. During winter, total abundance and biomass of mesozooplankton within the Bay were significantly lower, ranging from 2392.49 to 11145.29 ind.m⁻³, and from 34.49 to 42.49 mg.m⁻³, respectively (P<0.05). During both seasons, cosmopolitan copepod species 200–500μm in size dominated the total mesozooplankton counts, numerically and in biomass. Hierarchical cluster analyses identified distinct zooplankton groupings within the Bay during both the summer (three groupings) and winter (four groupings) surveys. The different groupings identified during the two seasons were not associated with any specific geographic region or hydrological feature. Nonetheless, a distinct seasonal pattern in the mesozooplankton community was evident, largely reflecting the increased abundance of mesozooplankton during the summer survey. Canonical Correspondence Analyses (CCA) indicated that the zooplankton community structure within Algoa Bay reflected a complex interaction between physical-chemical (e.g. temperature, water column stability, turbidity, and nitrate, dissolved oxygen and nitrite concentrations) and biological factors (e.g. microphytoplankton and picophytoplankton concentrations). These data provide baseline information towards long-term monitoring programs that will be conducted in Algoa Bay, as part of the South African Environmental Observation Network (SAEON), in the near future.
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- Date Issued: 2011
Adaptive livelihood strategies of the Basarwa: a case of Khwai and Xaxaba, Ngamiland district, Botswana
- Authors: Madzwamuse, Masego S
- Date: 2006
- Subjects: San (African people) -- Botswana , Land use -- Botswana , Rural development -- Botswana , Natural resources -- Management -- Botswana , Conservation of natural resources -- Botswana , Climatic changes -- Environmental aspects -- Botswana
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:4737 , http://hdl.handle.net/10962/d1005286 , San (African people) -- Botswana , Land use -- Botswana , Rural development -- Botswana , Natural resources -- Management -- Botswana , Conservation of natural resources -- Botswana , Climatic changes -- Environmental aspects -- Botswana
- Description: This thesis looks into the land use and natural resource management systems of Basarwa communities in Ngamiland in the northwest of Botswana. The study specifically focuses on Basarwa communities living in and on the edges of the Okavango Delta. The link between these communities and their natural resources is explored using the Sustainable Rural Livelihoods Framework and the Adaptive Renewal Cycle. The core assumption in this thesis is that livelihood strategies are constantly renewed and adapted to promote resilience in ecological and social systems. Fieldwork data collected between May 2000 and July 2001 and secondary data is used to deliberate on this point. The thesis confirms that the Basarwa’s livelihood strategies were adaptive only in as far as traditional livelihoods are concerned. The thesis traces the changes that the Basarwa have experienced as a result of policy restrictions through the different phases of the adaptive renewal cycle. The period following Independence in Botswana saw a policy shift which resulted in the Basarwa becoming landless. With mainly land-based livelihood strategies, the Basarwa were faced with new forms of crises and vulnerability which their traditional adaptive strategies were not designed for. It comes to the conclusion that the Basarwa are currently stuck in a reorganisation phase; however, the CBNRM Draft Policy of Botswana offers a glimpse of hope as it provides an opportunity for the Basarwa to progress through the full cycle of reorganisation, renewal, conservation and release.
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- Date Issued: 2006
The geological evolution and mineralised environments of the Tasman Geosyncline
- Authors: Pelham, D A
- Date: 1983 , 2013-04-03
- Subjects: Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5030 , http://hdl.handle.net/10962/d1006936 , Geosynclines -- Tasmania , Geology -- Tasmania , Ore deposits -- Tasmania , Mineralogy -- Tasmania
- Description: From introduction: The Tasman Geosyncline covers the eastern part of the continent of Australia, an area of over 2 million km'. The area has been a major source of Australian gold and tin production, and though it contains important base metal sulphide deposits, these are overshadowed in scale by the very large stratabound Proterozoic deposits (for example, Mt Isa, Broken Hill and McArthur River). This dissertation deals with the metallic mineral deposits of the Tasman Geosyncline, and as such does not include the extensive post Palaeozoic continental successions, with their important coal reserves, that overlie the deformed geosyncl i nal sequences.
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- Date Issued: 1983