Sample records for lake Victoria Kenya from WorldWideScience.org

 

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Sample records for lake victoria kenya from WorldWideScience.org

 

1

The use of stable carbon isotopes as tracers of ecosystem functioning in contrasting wetland ecosystems of Lake Victoria, Kenya

Aquatic macrophytes and sediments from two contrasting wetland ecosystems of Lake Victoria, Kenya (Lower Sondu Miriu and Kibos systems) were analyzed for their stable carbon isotopic composition in order to observe patterns in system functioning in these two ecosystems. The aquatic macrophytes had c...

2

Use of the fish endoparasite Ligula intestinalis (L., 1758) in an intermediate cyprinid host (Rastreneobola argentea) for biomonitoring heavy metal contamination in Lake Victoria, Kenya

Abstract Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a promising approach because of their capacity to bioconcentrate such elements. This study evaluated the effects of a cestode parasite, Ligula intestinalis, on the accumulation of lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) in the cyprinid fish, Rastreneobola argentea, in Lake Victoria, Kenya. This L. intestinalis/R. argentea model also was assessed as a bioindicator system for heavy metal contamination in the lake. Samples of 125 fish, 63 parasites, water and sediments were collected at four sites in the Kenya portion of the Lake Victoria basin characterized by variable heavy metal concentrations, for ICP-OES element analysis. The concentration of all four heavy metals in the ...

3

Integrated management of Striga hermonthica, stemborers, and declining soil fertility in western Kenya

Striga hermonthica (Delile) Benth., stemborers, and declining soil fertility are serious threats to sustainable food production in the Lake Victoria zone of Kenya. To address these constraints, promising integrated crop management technologies were evaluated, using a multi-locational design in four sub-locations in Siaya and Vihiga district (western Kenya) for six cropping seasons. Technologies evaluated consisted of the traditional maize (Zea mays L.) - bean (Phaseolus vulgaris L.) intercrop, maize - Desmodium (Desmodium uncinatum (Jacq.) DC.) push-pull intercrop, Crotalaria (Crotalaria ochroleuca G. Don) - maize rotation, and soybean (Glycine max (L.) Merr) - maize rotation. Within each of these systems, imazapyr-coated herbicide-resistant maize (IR-maize) and fertilizer were super-impos...

4

Variability in factors causing light attenuation in Lake Victoria

Summary 1. The major optical components controlling the attenuation of photosynthetic available radiation in nearshore areas of Lake Victoria (Uganda and Kenya) were examined and their impact compared. It was found that chromophoric dissolved organic matter and tripton play a dominating role in many nearshore areas, indicating that the coastal areas of Lake Victoria cannot be considered as Case I waters. 2. Concentrations of chromophoric dissolved organic matter declined with distance from the coast in an exponential manner indicating dilution and degradation of terrestrial sources of organic matter rather than in situ production. The importance of tripton was found to follow a similar pattern, while the relative importance of phytoplankton biomass in overall attenuation of photosynthetic ...

5

Seasonal Variability in Cadmium, Lead, Copper, Zinc and Iron Concentrations in the Three Major Fish Species, Oreochromis niloticus, Lates niloticus and Rastrineobola argentea in Winam Gulf, Lake Victoria: Impact of Wash-Off into the Lake

Trace metals Cadmium (Cd), Lead (Pb), Copper (Cu), Zinc (Zn) and Iron (Fe) were analyzed in edible portions of three main finfish species namely Lates niloticus, Oreochromis niloticus and Rastrineobola argentea sampled from various beaches of Winam Gulf, Lake Victoria, Kenya, in order to determine any seasonal and site variations and the results showed significantly (p�Rastrineobola argentea can be a significant source of heavy metals especially Zn, to humans, compared with Lates niloticus and Oreochromis niloticus, if only the muscle parts of the latter two are consumed.

6

Morphometric differentiation among haplochromine cichlid fish species of a satellite lake of Lake Victoria

Abstract Lake Victoria holds a young but species-rich assemblage of cichlid fishes, which form a monophyletic assemblage with additional species from surrounding water bodies, termed the Lake Victoria superflock. Lake Victoria is surrounded by smaller lakes that are somewhat disconnected from the main lake. Lake Kanyaboli is such a small lake, having markedly reduced species diversity, in part comprised of Lake Victoria species and endemics. Here, we studied the modern haplochromine component of the cichlid fauna, represented by Lipochromis maxillaris, Astatotilapia nubila, Xystichromis phytophagus and Astatotilapia sp. -Bigeye-, as well as a number of unidentified modern haplochromine specimens. We used landmark-based geometric morphometrics to study the degree of morphological divergence...

7

RNAi mediated resistance to diverse isolates belonging to two virus species involved in Cassava brown streak disease

Summary Cassava brown streak disease (CBSD) is emerging as one of the most important viral diseases of cassava (Manihot esculenta) and is considered today as the biggest threat to cassava cultivation in East Africa. The disease is caused by isolates of at least two phylogenetically distinct species of single stranded RNA viruses belonging to the family Potyviridae, genus Ipomovirus. The two species are present predominantly in the coastal lowland [Cassava brown streak virus (CBSV); Tanzania and Mozambique] and highland [Cassava brown streak Uganda virus (CBSUV); Lake Victoria Basin, Uganda, Kenya and Malawi] in East Africa. In this study, we demonstrate that CBSD can be efficiently controlled using RNA interference (RNAi). Three RNAi constructs targeting the highland species were generated...

8

White lupin leads to increased maize yield through a soil fertility-independent mechanism: a new candidate for fighting Striga hermonthica infestation?

Nitrogen (N)-deficiency and lack of phosphorus (P) availability are major constraints to maize yields in Western Kenya. In a two-season field study in the lake Victoria basin, we tested the capacity of white lupin (Lupinus albus (L.), cv. Ultra), as a nitrogen-fixing crop with a highly efficient P-acquisition capacity, to increase maize yields when used as a companion or cover crop, or as a source of organic matter. Each experiment was performed on three different fields (Vertisols) differing in N/P availability, previous cropping history and in levels of infestation by the parasitic weed Striga hermonthica (Del.) Benth. Our results show that white lupin led to significantly higher yields of maize when used as a cover crop. When lupin was grown as a companion crop, it also slightly enhance...

9

Managing the natural capital of papyrus within riparian zones of Lake Victoria, Kenya

The harvesting of natural products such as papyrus (Cyperus papyrus L.), whether for subsistence value or for the production of commodities intended for sale at local markets, contributes to the well-being of riparian peoples around Lake Victoria, Kenya. Serious losses of papyrus wetlands across East Africa have been reported, most of which are attributed to increasing anthropogenic stressors. Recent studies have called for restoration of these wetlands, emphasizing the need for sustainable harvesting strategies to be put in place, although few have provided suggestions as to how this might happen in practical terms and, crucially, with the consent and active participation of local communities as key stakeholders. Here we explore the socioeconomic characteristics of livelihoods based on pa...

10

Synergistic effects of pH and aluminum concentrations on the life expectancy of Tilapia (mozambica) fingerlings

Acid deposition on surface water causes a decrease of aquatic life. It has also been shown that increased acidity causes an increase in concentration of aluminum ions in these waters. Very little research has been done on effect of pH and aluminum on tropical aquatic organisms, particularly fish. Therefore, this study was undertaken to find the effect of pH and aluminum on tropical fish. Tilapia species of fish was chosen because it is abundant and is widely used as food in many communities in Kenya particularly around Lake Victoria. It is less sensitive to most toxic substances than most other aquatic species. Therefore, any toxicant that affects Tilapia, would most likely be toxic to other aquatic organisms.

11

Causes and effects of the Lake Victoria ecological revolution

Nile perch was introduced in Lake Victoria in the 1950s and exploded in number during the 1980s. The process of colonization of the lake by this predatory fish is described and explained. The changes in a number of other fauna elements of Lake Victoria are described and explained. Not only Nile perc...

12

B Chromosomes Have a Functional Effect on Female Sex Determination in Lake Victoria Cichlid Fishes

The endemic cichlid fishes in Lake Victoria are a model system for speciation through adaptive radiation. Although the evolution of the sex-determination system may also play a role in speciation, little is known about the sex-determination system of Lake Victoria cichlids. To understand the evoluti...

13

Genetic diversity and geographic distribution of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) genotypes associated with cassava in East Africa.

The genetic variability of whitefly (Bemisia tabaci) species, the vectors of cassava mosaic begomoviruses (CMBs) in cassava growing areas of Kenya, Tanzania, and Uganda, was investigated through comparison of partial sequences of the mitochondria cytochrome oxidase I (mtCOI) DNA in 2010/11. Two distinct species were obtained including sub-Saharan Africa 1 (SSA1), comprising of two sub-clades (I and II), and a South West Indian Ocean Islands (SWIO) species. Among the SSA1, sub-clade I sequences shared a similarity of 97.8-99.7% with the published Uganda 1 genotypes, and diverged by 0.3-2.2%. A pairwise comparison of SSA1 sub-clade II sequences revealed a similarity of 97.2-99.5% with reference southern Africa genotypes, and diverged by 0.5-2.8%. The SSA1 sub-clade I whiteflies were widely distributed in East Africa (EA). In comparison, the SSA1 sub-clade II whiteflies were detected for the first time in the EA region, and occurred predominantly in the coast regions of Kenya, southern and coast Tanzania. They occurred in low abundance in the Lake Victoria Basin of Tanzania and were widespread in all four regions in Uganda. The SWIO species had a sequence similarity of 97.2-97.7% with the published Reunion sequence and diverged by 2.3-2.8%. The SWIO whiteflies occurred in coast Kenya only. The sub-Saharan Africa 2 whitefly species (Ug2) that was associated with the severe CMD pandemic in Uganda was not detected in our study. PMID:23170210

14

Biodiversity of an interface zone of a nutrient-deficient lake (Nabugabo) in Uganda: macrophytes

Abstract Lake Nabugabo was a big bay of Lake Victoria before being separated from the latter by a sand bar about 4000 years ago. Whereas conductivity of Lake Victoria is 100 mScm-1 that of Nabugabo has been less than 30 m cm-2 since the Cambridge Scientific Expedition, 1962. Dissolved calcium carbonate is below detectable levels although nitrate and phosphate are not significantly different from those of Lake Victoria. However, the total cations and anions are five times more in Lake Victoria than Nabugabo. Along the eastern, southern and south-western margins of the lake is an emergent swamp composed of different types of plants. In most places, Miscanthidium violaceum forms a floating platform of matted roots and rhizomes which border the open lake; it is associated with Sphagnum, a type...

15

Panorama of Entebbe

742 x 114 mm. Five prints joined. A view from the hillside behind the town looking towards Lake Victoria, with the Kampala Road leading off northwards at the left of the panorama and Government House at the extreme right.

16

Geographical distribution of schistosomiasis and soil-transmitted helminths among school children in informal settlements in Kisumu City, Western Kenya.

This cross-sectional study determined the prevalence and distribution of schistosome and soil-transmitted helminth (STH) infections among 1,308 children aged 10-18 years in 34 primary schools in 8 informal urban settlements in Kisumu City, western Kenya. Stool samples were collected and examined for eggs of Schistosoma mansoni and STH (Hookworms, Ascaris lumbricoides and Trichuris trichiura) using the Kato-Katz technique. Haematuria was used as a proxy indicator of urinary schistosomiasis. Schools and water bodies were mapped using a geographical information system. Overall, 34% of children were infected with one or more helminth species whereas 16�2% of children were infected with one or more STH species. Schools in closest proximity to Lake Victoria and River Nyamasaria had the highest S. mansoni prevalence while schools with STH were more homogenously distributed. Mean school prevalence of S. mansoni infection was 21% (range=0-69�7%), S. haematobium 3�6% (range=0-12%), hookworms 6�1% (range=0-20%), A. lumbricoides 4�9% (range=0-18�4%), and T. trichiura 7�7% (range=0-18�6%). Helminth-related morbidities were not associated with infection. Our study demonstrates that schistosomiasis and STH are important health priorities among schools in informal settlements of Kisumu City, and highlights the need for routine deworming in similar settings. PMID:21679486

17

Images of earth and All Available Satellites

The Diomede Islands consisting of the western island Big Diomede, and the eastern island Little. PIA10631: Diomede ... PIA10625: Lake Naivasha, Kenya ..... 504x360x3. Average Tropical Relative Humidity from AIRS, Dec-Feb 2002-2005 ...

18

Images of Earth - NASA's Planetary Photojournal

The Diomede Islands consisting of the western island Big Diomede, and the eastern island Little. PIA10631: Diomede ... PIA10625: Lake Naivasha, Kenya ..... 504x360x3. Average Tropical Relative Humidity from AIRS, Dec-Feb 2002-2005 ...

19

Images of earth and All Available Satellites - NASA's Planetary ...

Average Tropical Relative Humidity from AIRS, Dec-Feb 2002-2005. PIA00523: Average .... 3804x3450x3. The Arctic Circle cuts through the western coast of Norway and the Saltfjellet-Svartisen National ... PIA10625: Lake Naivasha, Kenya ...

20

The population structure of Glossina fuscipes fuscipes in the Lake Victoria basin in Uganda: implications for vector control.

ABSTRACT: BACKGROUND: Glossina fuscipes fuscipes is the primary vector of trypanosomiasis in humans and livestock in Uganda. The Lake Victoria basin has been targeted for tsetse eradication using a rolling carpet initiative, from west to east, with four operational blocks (3 in Uganda and 1 in Kenya), under a Pan-African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). We genetically screened tsetse flies from the three Ugandan PATTEC blocks for genetic diversity at 15 microsatellite loci from continental and offshore populations to provide empirical data to support this initiative. METHODS: We collected tsetse samples from 11 sites across the Lake Victoria basin in Uganda. For genetic analysis purposes, we used 409 of the collected tsetse flies and added data collected for 278 individuals in a previous study. The flies were screened across 15 microsatellite loci and the resulting data were used to assess the temporal stability of populations, to analyze patterns of genetic exchange and structuring, to estimate dispersal rates and evaluate the sex bias in dispersal, as well as to estimate demographic parameters (NE and NC). RESULTS: We found that tsetse populations in this region were stable over 4--16 generations and belong to 4 genetic clusters. Two genetic clusters (1 and 2) corresponded approximately to PATTEC blocks 1 and 2, while the other two (3 and 4) fell within PATTEC block 3. Island populations grouped into the same genetic clusters as neighboring mainland sites, suggesting presence of gene flow between these sites. There was no evidence of the stretch of water separating islands from the mainland forming a significant barrier to dispersal. Dispersal rates ranged from 2.5 km per generation in cluster 1 to 14 km per generation in clusters 3 and 4. We found evidence of male-biased dispersal. Few breeders are successfully dispersing over large distances. Effective population size estimates were low (33--310 individuals), while census size estimates ranged from 1200 (cluster 1) to 4100 (clusters 3 and 4). We present here a novel technique that adapts an existing census size estimation method to a sampling without replacement scheme that was used in collecting tsetse flies. CONCLUSION: Our study suggests that different control strategies should be implemented for the three PATTEC blocks and that, given the high potential for re-invasion from island sites, mainland and offshore sites in each block should be targeted at the same time. PMID:23036153