Potential of Fungal Pathogens for Biological Control of Water Hyacinth

2020-06-25T22:52:51Z

Potential of Fungal Pathogens for Biological Control of Water Hyacinth Molo, R.; Ogwang, J. A. Surveys were undertaken in lakes Victoria, Kyoga and River Nile in Uganda between 2000 and 2001 to determine tungal pathogens associated with water hyacinth. Several potential pathogen isolates including Alternaria eichhorniae, Cercaspora sp. and Acremonium zonaium were identified. Isolates of Cercospora sp. and A. eichhorniae were evaluated Jot their effectiveness on water hyacinth plants in the screen house. The disease incidence and severity progressed with time in both isolates although there was' no significant 'difference (P>O.05) between the isolates and overall disease incidence and severity was not significant (P>O,05) There was no significant (P>O.05) effect of pathogens on overall plant fresh weight, number of Living leaves and daughter plants. but linear regression analysis showed a significant (P

Runoff, Soil and Nutrient Losses from Major Agricultural Land-use Practices in the Lake Victoria Basin, Uganda

2020-06-25T23:11:00Z

Runoff, Soil and Nutrient Losses from Major Agricultural Land-use Practices in the Lake Victoria Basin, Uganda Magunda, M. K. Soil degradation by water erosion is recognized lo be a major agricultural and environmental problem in the Lake Victoria basin. The objective of this study was to quantify runoff, soil and nutrient losses from major agricultural land-use types (Annual crops. banana. coffee and degraded rangelands) and assess the efficiency of contour bunds 'in reducing those losses in two selected micro-catchments of the Luke Victoria Basin. The experiment was conducted 011 13 runoff plots of 15 hy lO In. Each land-usc type was replicated three times, except banana. Con lour bunds were hand constructed two years after establishment of runoff plots. at 20-01 spacing interval. Before the establishment of contour bunds, the average annual runoff ranged between 315.47 and 2438.92 01' h::r'/yr. with relatively higher amount of rainfall water 10$s on rangelands compared to banana and coffee (p=O.022), The avarage annual soil loss ranged from 27.7 to g6.7 t/ha/yr, with higher soil [OS5 on annuals compared to banana and coffee (p=O.038). Seasonal soil losses contributed tor more than 75% of the annual losses for all agricultural land-use. while seasonal runoff contributed the same proportion only for banana and rangelands (p

Water Quality Improvement in the Inner Murchison Bay, Lake Victoria: A Case Study of Algal Removal at Gaba iI Water Treatment Plant

2020-06-25T23:09:36Z

Water Quality Improvement in the Inner Murchison Bay, Lake Victoria: A Case Study of Algal Removal at Gaba iI Water Treatment Plant Kanyesigye, C.; Kiwanuka, S.; Kaggwa, C. R.; Okurut, T. Gaba U, a conventional water treatment plant in Uganda, draws its raw water from the Inner Murchison Bay of Lake Victoria. Over the last six years (1995-2000), the water quality has changed as evidenced by increase in colour. turbidity and algae (chlorophyll-e) concentrations. Increased algal blooms in the Bay have had negative effects on the water treatment especially the clarification and filtration processes. In this paper, the performance of the treatment plant in terms of organic matter and algae removal was assessed using colour, turbidity, permanganate value and chlorophyll-a as indicator parameters. Identification and quantification of the dominant algae groups in the treatment process was done, and pilot clarification tests were carried out to identify options for algal removal. The removal of the colour. turbidity, permanganate value and chlorophyll-a to the levels of 88%, 71%, 65% and 85% respectively was found to take place mostly at the clarification stage. The results show that Gaba II water treatment plant does not perform well in terms of chlorophyll-a removal, especially at the filtration stage. At all the treatment stages, green and blue-green algae were found to be the dominant algal groups. The clarification efficiencies achieved in the pilot tests were 60-80% when using alum alone, 45-50% for alum with lime, 45-75% for alum with copper Sulphate and 50-75% fOTalum with chlorine. This showed that none of the combinations was a better algae removal option than the presently practised clarification using alum alone

Potential Impacts of Kirinya Wetland in Treating Secondary Municipal Effluent from Jinja Stabilisation Ponds

2020-12-14T10:43:23Z

Potential Impacts of Kirinya Wetland in Treating Secondary Municipal Effluent from Jinja Stabilisation Ponds Kansiime, F; Mwesigye, P. Kirinya West wetland is located on the Northern shores of Lake Victoria in Jinja- Uganda The wetland receives secondary treated effluent from the stabilisation ponds owned and operated by the National Water and Sewerage Corporation. The effluent finally enters Lake Victoria at the Napoleon Gulf. In this paper, we report the baseline water quality before the bio-mauipu-lation of tbe wetland and demonstrate the impact of Kirinya West wetland in treating secondary municipal effluent from the existing waste stabilisation ponds. The bio-manipulation of the wetland will entail spreading the effluent from the stabilisation ponds over the northern edges of the wetland so as to increase the treatment area of the wetland and its treatment efficiency. Bio-manipulation will increase tbe current treatment efficiency of the wetland, as the contact between plants and the wastewater will increase. The baseline data indicate that there was significant improvement of water quality as the wastewater flowed through the ponds (61% decrease in NH4-N, 46.9% in PO...p and 98% in faecal colifonns). There was a further reduction in the concentration of pollutants (80% for NH4-N and 98% for faecal coli forms) as the wastewater flowed through the wetland before reaching Lake Victoria at the Napoleon Gulf. However, channelised flow allowed wastewater to flow at the western edge of the wetland and this is associated to the effluent from the stabilisation pond that discharge at the northwestern edge of the wetland. CONCLUSION: The values of conductivity and concentrations of nutrients and faecal coliforms measured in this study, clearly demonstrate that the wastewater from the stabilisation ponds is channelled in Kirinya West wetland. Most of it flows on the western edge of the wetland in the same location where the effluent from the ponds is discharged. Low values of most variables at the swamp-lake interface of Napoleon Gulf, Lake Victoria, provide evidence that the Kirinya wetland, still provides some tertiary treatment, as the concentration and values of most variables decrease through the swamp towards the lake. Ammonium nitrogen from the last maturation pond further decreased by 80% and faecal coliforms by 98%. Overall the values in the effluent (nutrients and -faecal coliforms) from the ponds were still bigher than those recommended by NEMA for effluent discharge into water or on land (NEMA, 1999) Hopefully, the wetland will provide more effluent treatment (up to tertiary level) after it bas been bio-manipulated and the wastewater distributed over a large expanse of the wetland.

Buffering Capacity Studies in a Rural aod Urban Wetlands in Lake Victoria Catchment in Uganda

2020-06-25T22:34:15Z

Buffering Capacity Studies in a Rural aod Urban Wetlands in Lake Victoria Catchment in Uganda Busulwa, H.; Mafabi, P.; Malinga, A.; Kyambadde, R.; Ssekamate, J. Wetlands are known to filter water from catchments by retaining solid waste, and eroded sediments from catchment areas. Wetlands also reduce the impact of flooding, speed of flow, and hence store water while releasing it slowly. The extent to which the wetlands perform these roles was investigated in two wetlands, Kinawataka wetland with an industrial and heavily populated catchment, and Kisoma wetland with subsistence. agricultural catchment between January 1999 to JuLy 2001. Water samples were collected once a month from streams entering the wetlands, along transects within the wetland and at the out flow. Parameters investigated included pH, temperature, dissolved oxygen (DO), electric conductivity CEq, Total Dissolved Solids (TDS), orthophosphates, Total Phosphorus (TP). nitrates, Total Nitrogen (TN) and chemical oxygen demand (COD). Results showed that the urban Kinawataka wetland receives a lot of pollution from its catchment and this is considerably reduced as the water move through it to the out flow. Reductions of TN by 50% and TP by only 10% were noted. The rural Kisoma wetland however receives fewer nutrients from its catchment but releases more in its out flow. There were increases in orthophosphates to about 50%, TP to 40% and nitrates to 22%. In situations where large volumes of water was received especially after a heavy storm or during floods, the wetland capacity to buffer was impaired and the materials from the catchment would pass through it unbuffered. It is suggested that wetland buffering depends on the amount of nutrients and water inflow from the catchment, the wetland-slope. nature of the vegetation. size of the wetland, catchment rainfall and anthropogenic characteristics. The conditions within the wetlands modify the nature of the nutrients as the water flow through them

Effect of Water Harvesting on Species Diversity and Overall Rangeland Recovery in Kagera Microcatchement

2020-06-25T23:09:57Z

Effect of Water Harvesting on Species Diversity and Overall Rangeland Recovery in Kagera Microcatchement Abesiga, N. K. C.; Huising, J.; Mosango, M.; Majaliwa, M. J. Plant species diversity was investigated on ridges with and without water harvesting structures. The effect of water harvesting technology on the soil properties and rangeland recovery was also investigated. The experimental sites are located in Kifamba, Kakuuto County Rakai District. Plant species were recorded 00 a 50m horizontal transect aligned on the main transect running S-N on a 20 m lag. The quadrat method was used to sample grasses and herbs, whereas shrubs and trees were sampled on twenty five meter plots Onconsecutive horizontal transects. Soil physical and chemical properties, plant biomass and ground cover were determined along the landscape. Results indicate that. ridges with water harvesting structures bad higher species diversity than those without water harvesting structures (p

Seasonal Dynamics of The Phytoplankton Community in Relation to Environment in Lake Baringo, Kenya (Impact on the Lake's Resource management)

2020-06-25T23:10:54Z

Seasonal Dynamics of The Phytoplankton Community in Relation to Environment in Lake Baringo, Kenya (Impact on the Lake's Resource management) Odhiambo, W.; Gichuki, J. Studies were conducted in Lake Baringo between May 1994 and April 1995 to map temporal changes in productivity (phytoplankton standing stock) and attempt to relate these changes to environmental parameters in this ecosystem. Fourteen phytoplankton genera were recorded and described. Blue green algae (Cyanophyta) were the most dominant contributing 90.89% of the total biomass followed by green algaeChlorophyta (9.08%) and finally by diatoms - Bacillariophyta (1.23%). Seasonal changes were observed for the three major plant nutrients. Soluble reactive phosphorous (P04-P) ranged from 3.75 to 1l21lgP/I. Nitrate nitrogen (NOJ-N) ranged from 1- 110 Ilg Nil and finally the values for dissolved silica (SiOz) ranged from 2.1 - 20.5 mg SiOl!. Secchi disc depth ranged from 0.04-0.06 m. The study further observed that phytoplankton productivity in this ecosystem is limited by the high level of suspended silt, except for the dominant phytoplankton Microcystis aeruginosa (Kutz.) Kutz., which regulates its buoyancy by forming vacuoles, while other algal species sink out of the euphotic zone. Results obtained in this study show that the lake is undergoing drastic eutrophication resulting in deterioration of the water quality, frequent algal blooms, decreased fish yields and subsequently reduced income to the local communities. The eutrophication ofthe lake is further aggravated by unchecked damming and diversion of rivers flowing into the lake coupled with long spells of drought being experienced in the area and an increasing human and livestock population

Food and feeding habits of the African lungfish, Protopterus annectens (Owens) (Pisces: Sarcopterygii) in the flood plains of River Niger in Etsako east of Edo State, Nigeria

2020-06-25T23:10:03Z

Food and feeding habits of the African lungfish, Protopterus annectens (Owens) (Pisces: Sarcopterygii) in the flood plains of River Niger in Etsako east of Edo State, Nigeria Otuogbai, T. M.; Ikhenoba, A.; Elakhame, L. An analysis of the gut contents of African lungfish Protopterus annectens(O) using the frequency of occurrence, numerical and volumetric methods show that the fish has selective preference for diets of other fishes, molluscs, insects, crustaceans, annelids and plant materials. The condition factor ranged from 0.30 to 0.68 with a mean value of 0.50. The length weight relationship showed a linear proportionality with a calculated r-value (0.9682, P = 0.01, df = 207) indicating a positive allometric growth. Histological sections revealed striking similarity between the structures of the tongue and the paired fins (pectoral and pelvic). Both have similar types of taste buds, implying similar and possibly related functions. There is therefore, clear evidence that the paired fins play definite and active role in the feeding process of this fish. Such roles may include food location or detection, determination of food suitability and possibly palatability.

Preliminary investigation into the haematology of adult protopterus annectens (Owen) in Nigeria. (Short communication)

2020-06-25T23:11:52Z

Preliminary investigation into the haematology of adult protopterus annectens (Owen) in Nigeria. (Short communication) Otuogbai, T. D. S.; Ekhelar, A. J. HaematologicaI values other than mean cell haemoglobin concentration, were consistently higher in the male Protopterus annectens(O) than the female. These all showed significant linear correlation with weight at 5% level (P

Age validation of a tropical cyprinid, Rastrineobola argentea (Pellegrin 1904) by immersin in tetracycline hydrochloride and use phi prime

2020-06-25T22:56:12Z

Age validation of a tropical cyprinid, Rastrineobola argentea (Pellegrin 1904) by immersin in tetracycline hydrochloride and use phi prime Njiru, M.; Pitcher, T. J.; Pauly, D. To verify that increments observed in the otoliths of R. argentea were deposited daily, fish were immersed in tetracycline hydrochloride (TC) of 100 - 600 mg V between 2-24 hours. TC was found to be incorporated within 12 hours after immersion in 600 mg L·1• Otoliths were marked with a band that fluoresced in ultraviolet (UV) light Daily rings corresponded to the number of days the fish lived after marking. Strong dose of 600 mg L-1 TC did not produce arty diffuse bands and weaker doses of 100-500 mg L:' TC produced no rings. When daily increments were assumed to be deposited more than once per day, growth performance index (0') did not lie within the calculated mean (± S.D). These results suggested that R. argentea likely deposits increments daily. Counts of daily increments provide more accurate estimates of R. argentea age than previously available. The most significant advantage of using otolith ageing technique is the ability to produce individual rather than population statistics which have been available for R. argentea

African Journal of Tropical Hydrobiology and Fisheries