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| Registros recuperados: 64 | |
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| Mwevura, H.; Othman, O.C.; Mhehe, G.L.. |
| This paper reports on the levels of organochlorine pesticide residues in edible biota from the coastal area of Dar es Salaam city, Tanzania. Samples were collected from the Msimbazi and Kizinga rivers and from the coastal marine environment receiving waters from these rivers. The samples were analysed for various organochlorine pesticide residues using GC-ECD and the results confirmed with GC-MS. Dieldrin, p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT and 'Y- HCH were the only organochlorines detected at concentrations above the method detection limits (MDL). The samples showed significant differences in levels of residues depending on location, mode of feeding and age/size of analysed biota. p,p'-DDT to total DDT ratios in biota indicated recent contamination of... |
| Tipo: Journal Contribution |
Palavras-chave: Biota Organochlorine Marine pollution Baseline studies Pesticides ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/30 |
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| Msuya, F.E.; Neori, A.. |
| Macroalgae (seaweed) can be cultured effectively for the production of useful algal biomass and removal of nutrients from fishpond effluents. A land-based, tide/gravity-driven flow-through, fish-macroalgae integrated system was studied at Makoba Bay, Zanzibar, Tanzania, during May-October, 2000. Rectangular cages made of 1-inch mesh netting were constructed in channels that received the outflows of the fishponds. Four species of macroalgae were planted in the cages and compared for their usefulness as biofilters. Gracilaria crassa and Ulva reticulata grew at average rates of 1.5 and 1.2 %, respectively. Both species removed nitrogen as seaweed protein at rates of up to 0.4 g N/m2/d. The algal biomass produced was of good quality with protein dry weight... |
| Tipo: Journal Contribution |
Palavras-chave: Algae Biofilters Seaweed Proteins Marine aquaculture Nutrients Eutrophication Sustainable development ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/33 |
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| Kithakeni, T.; Ndaro, S.G.M.. |
| Some aspects of the biology of the sea cucumber Holothuria scabra Jaeger, 1935 were studied along the coast of Dar es Salaam. Samples of Holothuria scabra were collected from Kunduchi and Buyuni between January and December 1999. The abundance of Holothuria scabra was higher in Buyuni (3951) than in Kunduchi (1176). However, the level of exploitation per year from far reefs was higher in Kunduchi than in Buyuni. Sea cucumber harvesting by villagers is done monthly on intertidal areas and from reef flats near to the villages. Higher catches from Buyuni were recorded during August and November (perhaps due to light winds such that trips could be made to far-off reefs), while the catch from Kunduchi was relatively low throughout a year. The length- frequency... |
| Tipo: Journal Contribution |
Palavras-chave: Echinoderm fisheries Holothuria scabra Fishery biology Breeding Seasonality ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/38 |
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| Muhando, C.A.; Mohammed, M.S.. |
| Surveys conducted in the 1980s and early 1990s indicated that coral reefs in Tanzania were being degraded by overexploitation and destructive resource harvesting practices, particularly dynamite fishing and the use of dragnets, with concomitant reduction in fish abundance. Despite reduction in dynamite fishing on most parts of the Tanzania coast, recent coral reef surveys (1999 and 2000) have indicated that live coral cover and the health of reef corals were further degraded by the 1998 coral bleaching event. The extent of coral mortality differed between areas and species. Although the relative contribution of some taxa such as acroporids and pocilloporids decreased on most reefs surveyed, there was no evidence of species extinction. Despite extensive... |
| Tipo: Journal Contribution |
Palavras-chave: Coral reefs Mortality causes Benthos Reef fish Bleaching Degradation ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/25 |
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| Ngusaru, A.S.; Mohammed, M.S.. |
| The water and salt balance at Chwaka Bay in Zanzibar, Tanzania suggests that in order to balance the inflow and outflow of water, there must be a net flux of water from the bay to the open ocean during both the dry and wet seasons. The corresponding salt residual fluxes indicate advective salt export. However, exchange between the bay water with the open ocean replaces this exported salt via mixing. The freshwater residence times at Chwaka Bay are 24 days for dry and 37 days for wet season. The budgets for non-conservative materials indicate a net dissolved inorganic phosphorous (DIP) and dissolved inorganic nitrogen (DIN) flux from the bay to the ocean during wet season. The calculated DIPsyst and DINsyst suggest that the bay acts as a DIP and DIN source... |
| Tipo: Journal Contribution |
Palavras-chave: Water budget Salt budget Nutrient cycles ISW; Tanzania; Chwaka Bay. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/31 |
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| Jiddawi, N.S.; Stanley, R.D.; Kronlund, A.R.. |
| We examined the sampling effort required to estimate annual fishery landing statistics from the artisanal fishery. Using the observed variability among landing days in two villages in Zanzibar, Tanzania, we are able to present the relationship between predicted precision and sampling effort and take advantage of the strong correlation between lunar day and landings to demonstrate a potential gain in sampling efficiency of 30 % from stratification. The observed data are then used to simulate a 'virtual' year of landings for the two villages and demonstrate how the simulated year of observations can be used to simulate and assess various sampling strategies. In addition, it provides a heuristic tool for demonstrating the likelihood of how much anyone sampled... |
| Tipo: Journal Contribution |
Palavras-chave: Catch data Artisanal fisheries Coral reefs Fishery statistics ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/23 |
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| Shaghude, Y.W.; Wannas, K.O.; Mahongo, S.B.. |
| The biogenic assemblage and hydrodynamic settings of the tidally dominated reef platform sediments (TDRPS) east of the Zanzibar channel were investigated in order to characterise the carbonate sediments. Benthic foraminifera were found to be the most important group both in terms of average abundance (> 60 % by weight) and also in terms of spatial distribution with ommon occurrence in all sediments samples. Pelecypods with an average abundance of 8 % were slightly less widely distributed. The remaining groups occurred at lower average abundance and less frequently in the sediments. Current measurements indicated that the maximum current speed is higher during spring than during neap tides. The direction is phase-dependent with flood tidal current... |
| Tipo: Journal Contribution |
Palavras-chave: Biogenic deposits Hydrodynamics Carbonate sediments Reef formation Floods Ebb currents ISW; Tanzania. |
| Ano: 2002 |
URL: http://hdl.handle.net/1834/32 |
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| Registros recuperados: 64 | |
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