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Tanzania Journal of Science

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Full-Text Articles in Hydrology

Phylogenetic Relationships Of The Metazoan Parasites Of The Clariid Fishes Of Lake Victoria Inferred From Partial 18s Rdna Sequences, C. J. Mwita, G. Nkwengulila Dec 2010

Phylogenetic Relationships Of The Metazoan Parasites Of The Clariid Fishes Of Lake Victoria Inferred From Partial 18s Rdna Sequences, C. J. Mwita, G. Nkwengulila

Tanzania Journal of Science

Phylogenetic relationships among twenty two metazoan parasites recovered from seven species of clariid fish from Lake Victoria were analysed using partial 18S rDNA sequences. The 18S rDNA gene was amplified by polymerase chain reaction, directly sequenced, aligned and phylogenies inferred using maximum parsimony. Heuristic bootstrap MP searches yielded one most parsimonious tree (CI = 61%, HI = 39%), which showed that clariid parasites are monophyletic at higher taxonomic levels (Cestodea, Nematodea, Digenea and Crustacea). However the position of two trematodes (Allocredium mazoensis and Clinostomum sp.) and a nematode (Contracaecum sp.) were not stable. Despite the present findings, the study utilised …

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The Limnology Of The Lake Tanganyika Sub Catchment, H. H. Nkotagu, C. B. Athuman Dec 2007

The Limnology Of The Lake Tanganyika Sub Catchment, H. H. Nkotagu, C. B. Athuman

Tanzania Journal of Science

A limnological study covering the Lake Tanganyika sub catchment was conducted during the dry season at 20 accessible sites on 8 rivers, 2 lakes and a dam. Standard methods were used to determine the levels of abiotic parameters from water samples. Physical parameters including EC, Eh, turbidity, temperature, pH and secchi transparency were measured in situ while chlorophyll a was determined in the laboratory. Nutrients such as NO3-, SiO2, PO4 3- and Fe2+ were determined along with HCO3-. Significant changes in the levels of the abiotic parameters and nutrients have been observed at various sampling sites throughout the study area. …

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Limnological Studies Of The Pelagic Zone Of Lake Tanganyika At Kigoma, Tanzania., F. M. M. Chale Dec 2006

Limnological Studies Of The Pelagic Zone Of Lake Tanganyika At Kigoma, Tanzania., F. M. M. Chale

Tanzania Journal of Science

Some limnological parameters and chlorophyll a were determined for twelve months at a pelagic station near Kigoma. Temperatures ranged between 25.7 ºC and 27.3 ºC at the surface, and 24.1 oC and 24.7 oC at100 m. Thermal stratification persisted throughout the year with the thermocline oscillating between 15 m in October and 60 m in May. Dissolved oxygen concentrations were high at the surface, ranging between 6.59 mg l-1 and 8.15 mg l-1, while at 100 m the concentrations ranged from less than 0.20 mg l-1 to 1.94 mg l-1. Nitrate-nitrogen concentrations in surface water ranged between 26 µg N …

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Assessment Of The Status Of Lates Stappersii (Centropomidae) Stock In Lift-Net Fishery In Lake Tanganyika, Kigoma, Tanzania, I. A. Kimirei, Y. D. Mgaya Dec 2006

Assessment Of The Status Of Lates Stappersii (Centropomidae) Stock In Lift-Net Fishery In Lake Tanganyika, Kigoma, Tanzania, I. A. Kimirei, Y. D. Mgaya

Tanzania Journal of Science

An assessment of the status of Lates stappersii (Boulenger, 1914) stock in the lift-net fishery in Lake Tanganyika, Kigoma area, was carried out from January to December 2003. Results indicated that breeding is seasonal with peaks in February, July-August and December, and so was catch composition, with peaks in March, May and July–August that followed the abundance of its prey, Stolothrissa tanganicae. Catch per unit effort was similar between wet and dry seasons and peaked synchronously at all study sites probably as an indication of its abundance during those months; but also it could mean that the fishes were caught …

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Occurrence Of Metacercariae Of Diplostomum And Tylodelphys Species (Diplostomidae) In Clarias Species (Clariidae) Fishes From Lake Victoria, M. J. Musiba, G. Nkwengulila Jul 2006

Occurrence Of Metacercariae Of Diplostomum And Tylodelphys Species (Diplostomidae) In Clarias Species (Clariidae) Fishes From Lake Victoria, M. J. Musiba, G. Nkwengulila

Tanzania Journal of Science

The localisation and abundance of the metacercariae of Diplostomum and Tylodelphys species among the clariids of Lake Victoria were investigated between April and December 2001. Four species viz. Clarias gariepinus (271), C. alluaudi (65), C. werneri (50) and C. liocephalus (47) were examined, but only C. gariepinus was infected in the brain case and along the nasal cavity. Prevalence of metacercariae was high (>70%). Prevalence and mean intensity were similar between male and female fish. Mean intensity increased with fish size and declined in larger fish for D. mashonense; but declined with the increase in fish size for Tylodelphys …

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Influence Of Simultaneous Infestations Of Prostephanus Truncatus And Sitophilus Zeamaison The Reproductive Performance And Maize Damage, C P Rugumamu Oct 2005

Influence Of Simultaneous Infestations Of Prostephanus Truncatus And Sitophilus Zeamaison The Reproductive Performance And Maize Damage, C P Rugumamu

Tanzania Journal of Science

This study examined the combined effect of Prostephanus truncatus and  Sitophilus zeamais infestations on their reproductive performance and on the damage they cause to maize variety ZM 621 with 12.5% moisture content. The specific objective was to determine the number of the insect pests at F1 and F2 and the grain weight losses caused by the simultaneous pests\' infestations of shelled maize in the search for a control strategy. The results showed a change in adult insect numbers from F1 to F2. During single infestation the change in P. truncatus was 47.54% while in simultaneous infestations it was 41.66%. The …

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Recent Trends In Accumulation Rate, Elemental And Isotopic Composition Of Organic Matter In The Magu Bay, Lake Victoria, Ann Muzuka, Jf Machiwa, C Lugomela Oct 2005

Recent Trends In Accumulation Rate, Elemental And Isotopic Composition Of Organic Matter In The Magu Bay, Lake Victoria, Ann Muzuka, Jf Machiwa, C Lugomela

Tanzania Journal of Science

Stable isotope composition of organic carbon (OC), 14C data, OC and nitrogen content of recently deposited sediments in Magu Bay of Speke Gulf, Lake Victoria are used to document accumulation rates, sources and distribution of organic matter in the bay. The stable isotope values of both organic carbon and nitrogen decrease towards offshore, and this trend is associated with increase in the contents of organic carbon and nitrogen. The isotope results show that the organic material deposited in the bay are generally derived from C4 type of plants and are not transported far from the river mouth. Also the results …

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Fish Species And Size Distribution And Abundance In Different Areas In Lake Victoria, Tanzania, A I Chande, H A Mhitu Oct 2005

Fish Species And Size Distribution And Abundance In Different Areas In Lake Victoria, Tanzania, A I Chande, H A Mhitu

Tanzania Journal of Science

The study was carried out to investigate fish species distribution and abundance in different areas and size structure variations according to depth in Lake Victoria, Tanzania. Data were collected using a bottom trawl net during rainy and dry seasons in 2002. The results show that there were significant differences in catch rates between rainy and dry seasons (F (12, 12) = 2.69; p < 0.05). The rainy season recorded higher catch rates (36.25 - 106.61 kg/hr) than during the dry season (14.30 - 67.90 kg/hr). The haplochromines catch rates were higher during the dry season (11.08 kg/hr) than during the rainy season (7.72 kg/hr), however, the differences were not significant (c2 = 0.60, df = 1, p > 0.05). The distribution of the fish species in different areas recorded a significant difference during the dry season (Q = 18.254, df = 8, P < 0.001), while during the rainy season the difference was not significant (Q = 10.667, df = 8, P > 0.001). Moreover, the results show that small individuals dominated in shallow waters …

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Levels Of Nitrate And Phosphate In Some Satellite Lakes Within The Lake Victoria Basin, Tanzania, Jj Kulekana Dec 2004

Levels Of Nitrate And Phosphate In Some Satellite Lakes Within The Lake Victoria Basin, Tanzania, Jj Kulekana

Tanzania Journal of Science

Levels of nitrates (NO3-N) and phosphates (PO4-P) in some satellite lakes within the Lake Victoria basin were determined in Kagera (Lake Burigi), in Mara (River Mara) and in Mwanza region (Lake Malimbe) during August/September 2002 (dry season) and January/February 2003 (wet season). Water samples were collected using a van Dorn water sampler at chosen points from both deep and shallow areas of the water bodies. Results of the two surveys revealed that deep and shallow areas of the lakes had varying nutrient levels. In deep waters, PO4-P values ranged between 0.171-0.225mg/l, 0.067-0.364mg/l, and 0.043-0.096 mg/l in Lake Malimbe, Burigi and …

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Zooplankton Communities Of Selected Stations Of Lake Victoria, Rk Waya, Ja Mwambungu Dec 2004

Zooplankton Communities Of Selected Stations Of Lake Victoria, Rk Waya, Ja Mwambungu

Tanzania Journal of Science

Species composition and diversity of zooplankton communities of Lake Victoria (Tanzanian waters) were studied. In the shallow waters zooplankton were collected between March and April, and between August and December 2000. In deeper waters zooplankton were collected in August 2001. Overall, 20 genera and 29 species of zooplankton were observed in the shallow waters whereas 12 genera and 20 species of zooplankton were encountered in the deeper waters. The highest abundance was recorded in the deeper waters (2,481,633-2). In the shallow waters the cyclopoid copepods dominated the zooplankton community, the common species being Thermocyclops emini and Thermocyclops neglectus. In the …

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The Diversity Of Benthic Mollusks Of Lake Victoria And Lake Burigi, Ja Mwambungu Dec 2004

The Diversity Of Benthic Mollusks Of Lake Victoria And Lake Burigi, Ja Mwambungu

Tanzania Journal of Science

Molluscan diversity, abundance and distribution in sediments of Lake Victoria and its satellite lake, Lake Burigi, were investigated. The survey was carried out in January and February 2002 for Lake Victoria and in March and April 2002 for Lake Burigi. Ten genera were recorded from four zones of Lake Victoria while only three genera were recorded from Lake Burigi. In Lake Victoria the most diverse zone was Mara zone. The mollusca communities comprised of Bellamya, Gabbiella, Melanoides, Bulinus, Biomphalaria and Cleopatra (Gastropoda) and Corbicula, Eupera (Byssanodonta), Caelatura and Sphaerium (Bivalvia). Lake Burigi comprised of Melanoides, Bulinus and Biomphalaria. Melanoides tuberculata …

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Phytoplankton And Nutrients Studies In Magu Bay, Speke Gulf, Lake Victoria, (Tanzania) Following The 2001 Principal Rain Season, Jf Machiwa, C Lugomela, Ann Muzuka Dec 2004

Phytoplankton And Nutrients Studies In Magu Bay, Speke Gulf, Lake Victoria, (Tanzania) Following The 2001 Principal Rain Season, Jf Machiwa, C Lugomela, Ann Muzuka

Tanzania Journal of Science

Phytoplankton abundance and species composition in relation to some physico-chemical parameters were studied in Magu Bay, Lake Victoria, in May 2001. Investigations on the influence of Simiyu River on the biological and physical characteristics of the Bay were carried out. Surface and bottom currents flowed in the northeast direction close to the river mouth but were completely reversed after about 1.5 km from the river mouth. Most suspended particles brought in by the river were deposited within 0.5 km after entering the lake. Nutrient concentrations were generally high towards the eastern part of the bay as compared to the rest …

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Spatial Distribution Of Parasites Along The Gut Of The Catfish Clarias Gariepinus (Burchell, 1822) (Clariidae) From The Mwanza Gulf, Lake Victoria, G Nkwengulila, C Mwita Dec 2004

Spatial Distribution Of Parasites Along The Gut Of The Catfish Clarias Gariepinus (Burchell, 1822) (Clariidae) From The Mwanza Gulf, Lake Victoria, G Nkwengulila, C Mwita

Tanzania Journal of Science

The diversity, abundance and spatial distribution of parasites in the alimentary tract of Clarias gariepinus from the Mwanza Gulf were investigated. Ten parasite species were recovered; the Trematoda, Cestoda and Nematoda were each represented by three species while Dolops ranarum was the only crustacean recovered from the posterior part of the buccal cavity. Parasites diversity was highest in the small intestine and the stomach. Although the gut community of C. gariepinus studied was rich in intensity and individual numbers of helminth species, helminth infection in most sections of the gut comprised of monospecific infection and thus cohabiting interspecific interaction was …

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Diurnal Feeding Patterns And Food Habits Of Lates Niloticus In The Speke Gulf, Lake Victoria, Ha Mhitu, Ai Chande Dec 2004

Diurnal Feeding Patterns And Food Habits Of Lates Niloticus In The Speke Gulf, Lake Victoria, Ha Mhitu, Ai Chande

Tanzania Journal of Science

Twenty four hour sampling sessions were conducted to investigate the feeding patterns and food habits of Lates niloticus in the Speke Gulf, Lake Victoria during January/February, July/August and December 2002. Feeding activity was more pronounced during daytime mostly in morning hours than during the night. The most dominant food item was haplochromines. There was a significant difference in the occurrence of food items in the gut of L. niloticus with time. However, there was no significant difference in the occurrence of food items in the habitat at different times. The study concludes with a recommendation for fishermen to set their …

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Relationship Between Water Transparency And Species Richness Of Surviving Haplochromines In Selected Habitats In Mwanza Gulf - Lake Victoria, Hdj Mrosso, Bs Msuku, O Seehausen Dec 2004

Relationship Between Water Transparency And Species Richness Of Surviving Haplochromines In Selected Habitats In Mwanza Gulf - Lake Victoria, Hdj Mrosso, Bs Msuku, O Seehausen

Tanzania Journal of Science

Several of the surviving haplochromine species have been recorded in habitats of different water transparencies within the Mwanza Gulf. Sampling for the haplochromines was carried out in muddy, rocky, sandy and vegetated habitats. All of the recorded species had been reported previously. Fewer species were encountered than previously reported in the same sampling stations. There was evidence for positive correlation between species richness and water transparency that was reinforced with data on ecological differentiation. Further exploration and conservation measures of diversity have been suggested for Lake Victoria haplochromines.

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Fish Species Composition, Size Structure And Distribution In Non-Trawlable Areas Of Lake Victoria (Tanzania) With Emphasis On Mwanza Gulf And Mori Bay, Jdr Bayona, B Msuku, S Mzighani Dec 2004

Fish Species Composition, Size Structure And Distribution In Non-Trawlable Areas Of Lake Victoria (Tanzania) With Emphasis On Mwanza Gulf And Mori Bay, Jdr Bayona, B Msuku, S Mzighani

Tanzania Journal of Science

Fish diversity studies in littoral non-trawlable areas of Lake Victoria (Tanzania) were undertaken during six systematic surveys (November 2000 to December 2002). Information on fish species composition, size structure as well as spatial and temporal distribution was generated from gill-netting, beach-seining and electric fishing. Lates niloticus, indicated a declining trend in composition from 78.9% in March 2001 to 5.1% in July 2002. The species, however, increased to 40.6 % in catch composition as of December 2002, exhibiting somewhat inverse trends in distribution with Oreochromis niloticus and haplochromines in the lake fisheries. The surveys identified over 50 species for which 42 …

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Total Mercury Concentration In Common Fish Species Of Lake Victoria, Tanzania, J F Machiwa Dec 2004

Total Mercury Concentration In Common Fish Species Of Lake Victoria, Tanzania, J F Machiwa

Tanzania Journal of Science

Total mercury (THg) concentration was analysed in muscles of common fish species of Lake Victoria in the eastern and southern parts of the lake using cold vapour Atomic Absorption Spectrophotometric technique. Mercury concentration in all fish species was generally lower than the WHO maximum allowable concentration (500 ng/g ww) in edible fish parts. The maximum concentration of THg in Lates niloticus samples was 396 ng/g ww. Samples of Oreochromis niloticus had THg concentration ranging between <0.01 and 419 ng/g ww. Clarias gariepinus had THg concentration ranging between 1.2 and 239.1 ng/g ww. All less common fish species, such as, Labeo victirianus, Synodontis victoriae, Oreochromis leucostictus, Schilbe intermedius, Brycinus jacksonii, B. sadleri, Tilapia rendalii, Tilapia zilii and Haplochromines had THg concentration below the WHO maximum allowable limit (500 ng/g ww). The study showed that Hg from small-scale gold mining activities in Lake Victoria basin is not transported to the lake by fluvial discharge. Other possible pathways of Hg input to Lake Victoria are discussed.

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Parasites Of Clarias Gariepinus (Burchell, 1822) (Pisces: Clariidae) From The Mwanza Gulf, Lake Victoria, C Mwita, G Nkwengulila Dec 2004

Parasites Of Clarias Gariepinus (Burchell, 1822) (Pisces: Clariidae) From The Mwanza Gulf, Lake Victoria, C Mwita, G Nkwengulila

Tanzania Journal of Science

Seventeen species of parasites were recovered from 1071 Clarias gariepinus examined from the Mwanza Gulf of Lake Victoria. The parasite fauna comprised of four ectoparasites, a Monogenea, Hirudinea, crustacean and a Digenea; and fourteen endoparasites, five nematodes, five trematodes and three cestodes. Twelve parasite species were adults and five were larval forms. Ten were identified to species, six to genus and one to family level. Many species recorded are common to C. gariepinus, a few, e.g. Tylodelphys species is a first record in fish of Africa, thus represents a new host record. Spinitectus petterae is reported for the first time …

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Physical And Chemical Characteristics Of Water In Selected Locations In Lake Victoria, Tanzania, M A Kishe Dec 2004

Physical And Chemical Characteristics Of Water In Selected Locations In Lake Victoria, Tanzania, M A Kishe

Tanzania Journal of Science

A study conducted during the period of March/April 2002 aimed at measuring physical and chemical parameters in Tanzanian portion of Lake Victoria. Temperature and conductivity values were homogeneous among and within the study stations. Levels of dissolved oxygen (DO) ranged from 4 - 9 mgl-1 and there was significant difference between stations (P < 0.05). Water transparency was poor (< 2 m secchi depth) and differed from one sampling station to another. Ammonium nitrogen (NH4+-N), with few exceptions, showed the highest concentrations both at the bottom and near-surface followed by total phosphates (TP), nitrate nitrogen (NO2+NO3--N), nitrite nitrogen (NO2--N) and Soluble Reactive Silicon (SRSi). Concentrations of NH4+-N, TP and SRSi were high at bottom waters and the reverse was true for NO2+NO3--N and NO2--N. Differences in nutrients and physical water parameters among sampling stations were statistically significant (P < 0.05). However, temperature and nutrient levels at studied areas were higher than that of 50 years ago and the trend reversed for DO and transparency. This indicates that Lake Victoria is receiving organic materials from the catchment area leading to the decline of water quality. Long-term efforts for rehabilitation, conservation and sustainable management of the lake are suggested.

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Eutrophication Of Kigoma Bay Lake Tanganyika, Tanzania, Fmm Chale Jul 2003

Eutrophication Of Kigoma Bay Lake Tanganyika, Tanzania, Fmm Chale

Tanzania Journal of Science

Studies carried out in Kigoma bay (Tanzania) and at a deep water offshore station in lakeTanganyika showed marked differences in the water characteristics at the two locations. At the pelagic station, the water was more transparent (mean 11.47 m) and poor in phosphorus (mean 6.46 mg p/1 and 2.23 p/1 total and soluble reactive p, respectively). The mean transparency value for the bay was 4.05 m, and the levels of total and soluble reactive phosphorus were 14.75 mg p/1 and 4.34 mg p/1, respectively. The high water transparency coupled with low phosphorus levels in the pelagic zone indicate that the …

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Trials With Trickle Irrigation Equipment At Morogoro Preliminary Report, M.E. Parkes, M. E. Madata Jul 1975

Trials With Trickle Irrigation Equipment At Morogoro Preliminary Report, M.E. Parkes, M. E. Madata

Tanzania Journal of Science

The use of trickle irrigation is discussed with reference to Tanzania. A split-split plot design experiment is described in which yields of tomato, onion, and cabbage are compared for trickle and hand-irrigated plots, with different levels of fertiliser treatment. Yields for trickle-irrigated plots were significantly greater only for tomatoes. These results were achieved during July to October and a second attempt to grow the same vegetables during December to March was unsuccessful. Further trials are required to obtain a suitable rotation of vegetable crops from both a nutritional and agronomic point of view. Experience with the trickle irrigation equipment is …

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