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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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Comparative Analysis Of Mercury Content In Human Hair And Cosmetic Products Used In Dar Es Salaam, Tanzania, C P Kinabo Oct 2005

Comparative Analysis Of Mercury Content In Human Hair And Cosmetic Products Used In Dar Es Salaam, Tanzania, C P Kinabo

Tanzania Journal of Science

Total mercury (T-Hg) concentrations were analysed in human hairs and cosmetic products sold in Dar es Salaam Tanzania. The average total mercury (T-Hg) concentrations in the scalp hair of females using mercury based cosmetic creams and soaps ranged from 7.0 ± 0.4 to 880 ± 12 ppm. Highest T-Hg concentrations were found in females who work in beauty hair salons and the lowest concentrations were found among students. The average values in non-cosmetic users were found to be lower, with mercury ranging from 0.57 ± 0.07 to 8.29 ± 1.22 ppm. Analysis of cosmetic products indicated high values, ranging from …

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" Revised Distribution Of The African Freshwater Crab Genus Deckenia Hilgendorf, 1868" , Saskia Ae Marijnissen, Sven Lange, Neil Cumberlidge Jan 2005

" Revised Distribution Of The African Freshwater Crab Genus Deckenia Hilgendorf, 1868" , Saskia Ae Marijnissen, Sven Lange, Neil Cumberlidge

Journal Articles

No abstract provided.

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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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Species Composition And Biomass Estimates Of Zooplankton In Some Water Bodies Within Lake Victoria Basin, Rk Waya, Ai Chande Dec 2004

Species Composition And Biomass Estimates Of Zooplankton In Some Water Bodies Within Lake Victoria Basin, Rk Waya, Ai Chande

Tanzania Journal of Science

Zooplankton communities were identified and their abundance and biomass estimated in some selected satellite lakes and Mara River in Lake Victoria basin, during wet and dry seasons in 2002. Samples were collected from eight water bodies. Three stations were sampled from each water body using a plankton net (40 µm mesh size) hauled vertically through the water column. The zooplankton community comprised mainly crustacea and rotifers. The results show that the number of species collected during the wet and dry seasons was 31 species and 28 species, respectively. The Shannon wiener diversity indices were not significantly different (Mann-Whitney U Test …

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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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Phytoplankton Species Diversity And Abundance In Satellite Lakes Of Lake Victoria Basin (Tanzanian Side), Bc Sekadende, Ase Mbonde, S Shayo, Tj Lyimo Dec 2004

Phytoplankton Species Diversity And Abundance In Satellite Lakes Of Lake Victoria Basin (Tanzanian Side), Bc Sekadende, Ase Mbonde, S Shayo, Tj Lyimo

Tanzania Journal of Science

Studies on phytoplankton species diversity and abundance were carried out in 8 selected satellite lakes within the Lake Victoria basin during two wet seasons (March-April 2002 and January-February 2003) and one dry season (August-September 2002). Higher species richness (76 species) of phytoplankton species was recorded in rain season than in dry season (47 species). The observed species represents six classes, cyanophytes, chlorophytes, cryptophytes, basillariophytes, euglenophytes and dinophytes, of fresh water algal flora. Species diversity was generally low, with diversity indices (H\') ranging from 0.21 for Lake Kyarano to 0.09 for Lake Ikimba. On the contrary, Lake Katwe was richer in …

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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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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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Diel Vertical Migration Of Zooplankton In The Tanzanian Waters Of Lake Victoria, Rk Waya Dec 2004

Diel Vertical Migration Of Zooplankton In The Tanzanian Waters Of Lake Victoria, Rk Waya

Tanzania Journal of Science

The diel vertical migration of zooplankton was studied in the Southern part of Lake Victoria in January and July 2002. A van dorn water sampler was used to collect zooplankton. In January 2002, zooplankton showed a pronounced diel vertical migration whereby zooplankton were moving upward at around sunset and swimming downward at sunrise. In July 2002 zooplankton showed diel vertical migration, but at around midnight Thermodiaptomus galeboides, Thermocyclops emini, Tropocyclops tenellus, cyclopoid copepodites, nauplius larvae and some rotifers showed downward movement. The diel vertical migration of zooplankton seems to be influenced by food, predation and light.

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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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Studies On The Fisheries And Biology Of Oreochromis Urolepsis (Pisces: Cichilidae) In The Mtera Resorvoir (Tanzania), F M M Chale Dec 2004

Studies On The Fisheries And Biology Of Oreochromis Urolepsis (Pisces: Cichilidae) In The Mtera Resorvoir (Tanzania), F M M Chale

Tanzania Journal of Science

The fisheries and some aspects of the biology of Oreochromis urolepis of the Mtera Reservoir (Tanzania) were examined in August 2002. It was observed that there was no proper management of the reservoir's fisheries. Beach seine fishing dominated the fishery. Nearly all the O. urolepis caught by this type of gear were juveniles. The number of fish caught by the beach seines was very high, some times up to 4,000 fish per haul. The beach seines also destroy the spawning sites for the tilapias. Mean total lengths of O. urolepis caught in gillnets of legal mesh sizes (ranging from 88 …

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Changes In Population Structures Of The Major Species In Selected Satellite Lakes Around Lake Victoria Following Changes In Fishing Effort, E F B Katunzi, M A Kishe Dec 2004

Changes In Population Structures Of The Major Species In Selected Satellite Lakes Around Lake Victoria Following Changes In Fishing Effort, E F B Katunzi, M A Kishe

Tanzania Journal of Science

This paper evaluates the impacts of reduction in effort, increase in mesh sizes, and prohibition of illegal fishing gears in selected satellite lakes around Lake Victoria. The study was carried out in six satellite lakes by making investigations on fish collected from experimental and artisanal fisheries. The fishes were analysed for length frequencies, weight and numbers caught to determine the population structure of the fishes. Indiscriminate fishing by deploying illegal gears and increased fishing effort due to open access policy, the catch and diversity of the species in these lakes has declined. Establishment of Conservation Management Units (CMUs) as an …

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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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Phytoplankton Species Diversity And Abundance In The Near Shore Waters Of Tanzanian Side Of Lake Victoria, Ase Mbonde, S Shayo, Bc Sekadende, Tj Lyimo Dec 2004

Phytoplankton Species Diversity And Abundance In The Near Shore Waters Of Tanzanian Side Of Lake Victoria, Ase Mbonde, S Shayo, Bc Sekadende, Tj Lyimo

Tanzania Journal of Science

The survey was carried out in January/February and July/August 2002 to investigate phytoplankton species diversity, spatial distribution, numerical abundance and total biomass (chlorophyll a concentration) in 10 selected stations on the Tanzanian side of Lake Victoria. At each station, samples for diversity data were collected by plankton net, which was towed at the surface water, while those for spatial distribution and abundance were collected using a 1 l Van Dorn water sampler. A total of 113 species belonging to 52 different genera were identified. Cyanobacteria were the most diverse group in both seasons. The concentration of chlorophyll a ranged from …

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Phylogenetic Relationships Of African Microhylid Frogs Inferred From Dna Sequences Of Mitochondrial 12s And 16s Rrna Genes, Simon P. Loader, David J. Gower, Kim M. Howell, Nike Doggart, Mark-Oliver Rödel, Barry T. Clarke, Rafael O. De Sá, Bernard L. Cohen, Mark Wilkinson Dec 2004

Phylogenetic Relationships Of African Microhylid Frogs Inferred From Dna Sequences Of Mitochondrial 12s And 16s Rrna Genes, Simon P. Loader, David J. Gower, Kim M. Howell, Nike Doggart, Mark-Oliver Rödel, Barry T. Clarke, Rafael O. De Sá, Bernard L. Cohen, Mark Wilkinson

Biology Faculty Publications

The phylogenetic relationships of microhylid frogs are poorly understood. The first molecular phylogeny for continental African microhylids is presented, including representatives of all subfamilies, six of the eight genera, and the enigmatic hemisotid Hemisus. Mitochondrial 12S and 16S rRNA sequence data were analysed using parsimony, likelihood and Bayesian methods. Analyses of the data are consistent with the monophyly of all sampled subfamilies and genera. Hemisus does not nest within either brevicipitines or non-brevicipitines. It is possibly the sister group to brevicipitines, in which case brevicipitines might not be microhylids. Phrynomantis and Hoplophryne potentially group with non-African, non-brevicipitine microhylids, in …

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"Notes On The Taxonomy Of Potamonautes Obesus And Potamonautes Calcaratus From Eastern And Southern Africa" , Sadie K. Reed, Neil Cumberlidge Jan 2004

"Notes On The Taxonomy Of Potamonautes Obesus And Potamonautes Calcaratus From Eastern And Southern Africa" , Sadie K. Reed, Neil Cumberlidge

Journal Articles

No abstract provided.

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"Two New Species Of Platythelphusa A. Milne-Edwards, 1887 And Comments On The Taxonomic Position Of P. Denticulata Capart, 1952 From Lake Tanganyika" , Saskia Ae Marijnissen, Frederick R. Schram, Neil Cumberlidge, Ellinor Michel Jan 2004

"Two New Species Of Platythelphusa A. Milne-Edwards, 1887 And Comments On The Taxonomic Position Of P. Denticulata Capart, 1952 From Lake Tanganyika" , Saskia Ae Marijnissen, Frederick R. Schram, Neil Cumberlidge, Ellinor Michel

Journal Articles

No abstract provided.

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Insect Infestation Of Maize, Zea Mays (L.) In Indigenous Storage Structures In Morogoro Region, Tanzania, Cp Rugumamu Dec 2003

Insect Infestation Of Maize, Zea Mays (L.) In Indigenous Storage Structures In Morogoro Region, Tanzania, Cp Rugumamu

Tanzania Journal of Science

Insect infestations and losses of maize stored in four types of indigenous storage structures in Morogoro Region, Tanzania were investigated. Infestation levels and weight losses caused by the larger grain borer, Prostephanus truncatus (Horn) and the maize weevil, Sitophilus zeamais (Motsch.) were found to differ significantly in the four types of storage structures (Dari, Kihenge, Kichanja and Reli). Lower infestation levels by the two pests and less weight losses were observed inDari and Kihenge than in Kichanja and Reli. The infestations and weight losses exhibited a significant trend that was in the order, Dari< Kihenge < Kichanja < Reli. These findings suggest that Dari and Kihenge are more appropriate for the incorporation in Integrated Pest Management (IPM) for P. truncatus and S. zeamais in Morogoro Region.

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Antibacterial Activities Of Constituents From Isolona Cauliflora And Cleistochlamys Kirkii, Ac Odebode, Sjm Mdachi, Cc Joseph, Bn Irungu Dec 2003

Antibacterial Activities Of Constituents From Isolona Cauliflora And Cleistochlamys Kirkii, Ac Odebode, Sjm Mdachi, Cc Joseph, Bn Irungu

Tanzania Journal of Science

Antibacterial activities of caulindole D, a mixture of caulindole E and F, pinocembrin and an oxyheptanoid (cleistenolide), obtained from stem barks of Isolona cauliflora and Cleistochlamys kirkii, on Staphylococcus aureus and Pseudomonas phaseolicola were determined. An in vitro assay test by paper disc method showed that the caulindole D, E and F from Isolona cauliflora produced no inhibition zone on both bacteria pathogens at 100-200 ppm while cleistochlamic acid from C. kirkii showed weak to moderate inhibition zone at 100-200 ppm. At concentration above 200 ppm, the bacteria pathogens were inhibited by all the compounds isolated from the plant extracts. …

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Metal Concentrations In Sediment And Fish Of Lake Victoria Near And Away From Catchments With Gold Mining Acctivities, Jf Machiwa Dec 2003

Metal Concentrations In Sediment And Fish Of Lake Victoria Near And Away From Catchments With Gold Mining Acctivities, Jf Machiwa

Tanzania Journal of Science

Concentrations of metals in sediment and fish as well as organic matter contents of sediment from Lake Victoria were investigated. The objective of the study was to compare levels of metals in sediment and fish from areas of the lake that are within and outside catchments with gold mining activities.The results showed that the concentration of As was less than 6 mg g-1 dw and Cd was below 1.9 mg g-1 dw in sediment samples. Lead, zinc and copper concentrations were highest (58.1±17.6 mg g-1 dw, 101.9±20.6 mg g-1 dw and 32.6±2.8 mg g-1 dw respectively) in sediment samples that …

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Heavy Metal Contamination Of Mangrove Sediments And The Associated Biota In Dar Es Salaam, Tanzania, Sd Mremi, Jf Machiwa Jul 2003

Heavy Metal Contamination Of Mangrove Sediments And The Associated Biota In Dar Es Salaam, Tanzania, Sd Mremi, Jf Machiwa

Tanzania Journal of Science

Mangrove wetlands are efficient in trapping pollutants that may have detrimental effects on mangrove dependent food chains. Mangrove ecosystems that are within urban areas are likely to suffer more from chemical pollution than those in rural areas. Heavy metals in mangrove plant parts, sediments and crabs from mbweni, msimbazi and mtoni mangrove ecosystems in Dar es salaam were analysed using an atomic absorption spectrophotometer, in order to assess the impact of heavy metal pollution on mangrove biota. Sediment samples from msimbazi and mtoni mangrove areas which are located within the city, had higher levels of pb, zn and cu than …

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Effects Of Chromium Uptake On The Growth Characteristics Of Eichhornia Crassipes (Mart.) Solms, Zk Rulangaranga, Al Mugasha Jul 2003

Effects Of Chromium Uptake On The Growth Characteristics Of Eichhornia Crassipes (Mart.) Solms, Zk Rulangaranga, Al Mugasha

Tanzania Journal of Science

The uptake of chromium from fresh water by Eichhornia crassipes was studied under greenhouse conditions where the species was raised in culture solutions containing varying concentrations of chromium (VI) ions. There were positive correlations between the concentration of chromium in the culture media and the amounts of the metal accumulated in the tissues of E. crassipes at any given time. Furthermore, the total accumulated chromium in the tissues of E crassipes increased with increase in the duration for which the plant was exposed to the nutrient solutions containing chromium ions. Most of the absorbed chromium was accumulated in the roots …

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Polystomatidae (Monogenea) Of Southern African Anura: Eupolystoma Vanasi N. Sp. Parasitic In Schismaderma Carens (Smith), Louis H. Du Preez, Richard C. Tinsley, Rafael O. De Sá Jan 2003

Polystomatidae (Monogenea) Of Southern African Anura: Eupolystoma Vanasi N. Sp. Parasitic In Schismaderma Carens (Smith), Louis H. Du Preez, Richard C. Tinsley, Rafael O. De Sá

Biology Faculty Publications

Eupolystoma vanasi is described as a new species of the Polystomatidae parasitic in the urinary bladder of Schismaderma carens in Northern Province and KwaZulu-Natal Province, South Africa. This is the third Eupolystoma species described from Africa and the first polystomatid from Schismaderma, an anuran genus that is primitive with respect to the other African bufonids in which Eupolystoma has been recorded. The species is distinguished by body size (this is the largest Eupolystoma known; mean length of adults 6 mm), by genital spine number (4 in comparison with 6-9 in other species), marginal hooklet length (greater than in other …

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Assessment Of Wind Energy Potential For Eletricity Generation In Setchet, Hanang, Tanzania, A. S. Kasasi, R. M. Kainkwa Dec 2002

Assessment Of Wind Energy Potential For Eletricity Generation In Setchet, Hanang, Tanzania, A. S. Kasasi, R. M. Kainkwa

Tanzania Journal of Science

Tanzania depends heavily on hydropower for her electricity demand and experiences power shortage during the dry seasons. Wind energy is proposed as an alternative source of electricity to the fossil fuel generators during the dry season, the latter are normally used to supplement the shortfall in hydro-electricity generation. Fossil fuel generators produce emissions that are toxic and as such degrade the environment. Wind speed data from a site called Setchet is used to illustrate that the available wind energy can be harvested to generate electricity that can supplement the shortfall of electricity. The windy season, which is from July to …

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Morphometrics Of The Pancake Tortoise (Malacochersus Tornieri) In Tanzania, J. Kabigumila Dec 2002

Morphometrics Of The Pancake Tortoise (Malacochersus Tornieri) In Tanzania, J. Kabigumila

Tanzania Journal of Science

Observations were made of the morphometrics of captive pancake tortoise (Malacochersus tornieri) in June 1995. Carapace length ranges for immature tortoises and adult males and females were 50-115, 123-160 and 129-171 mm respectively. The respective carapace widths were 45-90, 97-130, and 92-129 and 97-130 mm. Carapace height ranges were 15-29, 25-40 and 117-159 mm, respectively, while plastron length ranges were 45-110, 108-150 and 117-159 mm. The relationships between carapace length and width (males: y = 13.763+0.639x; females: y = 17.302+0.639x) and height (males: y=6.851+0.170x, females: y = 17.274+0.170x) were isometric and sexually dimorphic in adults. The relationship between carapace length …

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Spatial-Temporal Changes In Phytoplankton Biomass And Primary Production In Chwaka Bay, Zanzibar, M. N. S. Kyewalyanga Dec 2002

Spatial-Temporal Changes In Phytoplankton Biomass And Primary Production In Chwaka Bay, Zanzibar, M. N. S. Kyewalyanga

Tanzania Journal of Science

Spatial-temporal variations in phytoplankton primary production (PP) and biomass (B) were studied for a period of about one year, from July 1999 to July 2000. In addition, changes in corresponding environmental variables were examined. Sampling took place at two stations in Chwaka Bay, one located in mangrove areas, Station I, and the other in an open area, Station II. Although there were changes both with location and time, there were no clear seasonal trends. Generally, the phytoplankton biomass and primary production (mg C m-3 h-1) were higher at Station I than at Station II. However, specific production, that is, primary …

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Studies On Benthic Denitrification In The Chwaka Bay Mangrove Sediments, Zanzibar, Sm Mahommed, Rw Johnstone Nov 2002

Studies On Benthic Denitrification In The Chwaka Bay Mangrove Sediments, Zanzibar, Sm Mahommed, Rw Johnstone

Tanzania Journal of Science

Denitrification was measured at three sites in a narrow tidal creek in the Chwaka mangrove ecosystem. Denitrification arising from water column nitrate (Dw) was low (< 0.1μM Nm-2h-1) and there was little spatial and seasonal variation in Dw rates in the creek. Coupled nitrification-denitrification (Dn) was found to be low, but within the range measured in other mangrove sediments. Average values ranged from 0.01 to 0.45 μM Nm-2h-1 and showed strong spatial variations. The low denitrifcation rates observed in the creek were possibly as a result of the low availability of NO3 and high C:N values of the organic matter in the sediment. Spatial variations in denitrification rates were due to variations in concentration levels of organic matter and possibly to disproportionate competition for inorganic nitrogen between denitrifiers and benthic autotrophs among sites. There were no seasonal differences in denitrification rates. Results from the present study suggest that sediment denitrification does not play a major role as a sink for N in this ecosystem

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