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Registros recuperados: 5
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Effect of Frequency of Fertilisation on Abundance of Rotifers and Protozoa in Flooded Ponds and Simulation Tanks OceanDocs
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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Effects of Fish Culture on Water Quality of an Integrated Mariculture Pond System. OceanDocs
Mmochi, A.J.; Dubi, A.M.; Mamboya, F.A.; Mwandya, A.W..
Six mariculture ponds were flooded with seawater since 1996. During this time the ponds were stocked with finfish (milkfish and rabbitfish), which were fed on locally produced fish feed. Some water quality parameters such as temperature, salinity and oxygen saturation were measured twice a day for three years (1998-2000), while nutrient concentrations were measured weekly for one year. Both nutrient concentration and oxygen saturation levels have shown a trend indicating eutrophication. Oxygen concentration changed from an average of 7.16 mg/l in October 1998 to 2.2 mg/l in March 2000 with a negative linear regression of 0.69 during the morning hours. From August 1998 to April 1999 dissolved inorganic ammonia concentration increased by 9 µg-at NIl, from...
Tipo: Journal Contribution Palavras-chave: Marine aquaculture Water quality Nutrients Dissolved oxygen Eutrophication Fish culture Fish feed Shellfish culture Seaweed culture Biofiltration Environmental pollution ISW; Tanzania.
Ano: 2002 URL: http://hdl.handle.net/1834/26
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Influence of environmental variables on planktonic and phytobenthic communities in earthen ponds at Makoba, Zanzibar OceanDocs
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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Preliminary study on hatching of rotifers (Brachionus plicatilis) and copepods (Cyclopoida): response to flooding and organic fertilisation OceanDocs
Mwandya, A.W.; Kyewalyanga, M.S.; Valdenberg, A..
The effect of water flooding, organic fertiliser application and salinity manipulation in stimulating the hatching of rotifer resting eggs was investigated during the dry season (in August/September 1999) in simulation tanks and earthen ponds at Makoba, Zanzibar. The majority of hatched zooplankton included rotifers, identified as Brachionus plicatilis, and other zooplankton such as copepods and protozoa were present in small numbers. The number of rotifers hatched in simulation treatments with low salinity was higher than the values in treatments containing undiluted seawater. Up to 22 ± 1.5 (mean ± SE) rotifers/ml were counted in treatments with low salinity, whereas only a maximum of 13 ± 1. rotifers/ml were found in high-salinity treatments. On the...
Tipo: Journal Contribution Palavras-chave: Eggs; Resting spores; Salinity; Flooding; Hatching; Eggs; Salinity; Fertilization; Http://aims.fao.org/aos/agrovoc/c_2502; Http://aims.fao.org/aos/agrovoc/c_6751; Http://aims.fao.org/aos/agrovoc/c_2863.
Ano: 2004 URL: http://hdl.handle.net/1834/1093
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Water Quality in the Integrated Mariculture Pond Systems (IMPS) at Makoba Bay, Zanzibar, Tanzania OceanDocs
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
Registros recuperados: 5
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