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| Kyewalyanga, M.S.; Mwandya, A.W.. |
| Experiments to assess a suitable rate of fertilisation of earthen ponds for production of rotifers and protozoa were conducted in April 2000. Production of rotifers and protozoa (hereinafter collectively referred to as rotifers) was stimulated by flooding the ponds using seawater and rainfall. In the simulations, seawater diluted to 20 ppt salinity activated initial production. In all systems, the fertiliser concentration was approximately 1 ml of chicken manure to 2 litres of seawater. Three different rates of fertilisation were tested. The results clearly showed that the higher the frequency of addition of manure, the higher the production of rotifers per ml. Fertilised ponds had maximum averages of between 64 and 76 rotifers/ml as compared to a maximum... |
| Tipo: Journal Contribution |
Palavras-chave: Rotifers; Fertilisation rate; Earthen ponds; Nutrients; Simulatioru. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/22 |
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| Kyewalyanga, M.S.; Mwandya, A.W.. |
| A study was conducted between July 2002 and June 2003 to assess the role of salinity, temperature, pH and dissolved oxygen on the abundance of planktonic (phyto- and zooplankton) and phytobenthic (algal mats) communities in shallow (40 cm depth) earthen ponds at Makoba, Zanzibar. Among the zooplankton, rotifer abundance peaked during the rainy period (salinity of 27–42‰) while protozoa and copepods were most abundant during the dry period (max salinity of 70‰). However, no season effects were seen on the phytobenthos. The most abundant genera were Pseudonitzschia sp., Schizothrix sp., Microcoleus sp. and Oscillatoria sp. and in general, algal mats were available throughout the year. Other variables such as temperature, pH and oxygen concentration did not... |
| Tipo: Journal Contribution |
Palavras-chave: Pseudonitzschia; Schizothrix; Microcoleus; Oscillatoria; Environmental variables; Planktonic organisms Environmental conditions Salinity Temperature Fish ponds Algal mats Environmental conditions Salinity Temperature http://aims.fao.org/aos/agrovoc/c_32980 http://aims.fao.org/aos/agrovoc/c_6751 http://aims.fao.org/aos/agrovoc/c_7657. |
| Ano: 2004 |
URL: http://hdl.handle.net/1834/1109 |
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| Mmochi, A.J.; Mwandya, A.W.. |
| The Makoba integrated mariculture pond system project (IMPS) has been on-going since 1998. Except for a period from mid 1999 to 2001, various water quality parameters, namely temperature, salinity, pH, dissolved inorganic nutrients and dissolved oxygen concentration and saturation, have been monitored continuously. In 2002, measurement of sediment oxygen demand (SOD) and consumption of oxygen by sediments was initiated. Dissolved oxygen concentration varied from the highest monthly average of 7.16 mg/l in October 1998, to 2.2 mg/l in March 2000 (r = –0.69). Nutrient concentrations remained moreor- less constant, except in the finfish ponds, where slight variations were recorded. The lowest concentration of ammonium-nitrogen (3.02 mg-at N/l) was recorded in... |
| Tipo: Journal Contribution |
Palavras-chave: Mariculture; Water quality. |
| Ano: 2003 |
URL: http://hdl.handle.net/1834/966 |
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