Effects of Parasitism on the Production and Productivity of caged Oreochromis niloticus in Winam Gulf of L. Victoria

The general objective of this study was to assess the effects of parasitism on the production and productivity of caged Oreochromis niloticus in Winam Gulf of L. Victoria. With the need to increase food production through fish products amid overfishing and pollution stress in the lake, cage farming is seen to have the potential to bridge the fish supply and demand gap continues to widen. Cage culture is a new technology in the offing that needs to be explored to justify its potential. Fish parasites are always a threat in an enclosed culture system and because of this, it is necessary to assess their effects on fish condition factors before recommendation. It is because of this reason that a total of 480 caged Oreochromis niloticus were purchased and examined for parasites using the recommended procedures for parasitological analysis. The class Trematoda which included seven taxa were found to be the most common and prevalent parasites in cages of the Winam Gulf. This was attributed to the presence of piscivorous birds which are definitive hosts seen more often around the culture systems and also overstocking observed and reported during the study period which increases the spread and transmission of parasites from one fish to another. Despite the prevalence, infestation did not affect the fish condition factor in all the study areas as the majority of infected fish recorded between good and excellent body condition factors. This was due to low mean intensities recorded and a shorter period of exposure to parasitic infestation as most farmers were barely 3 years into the system. In conclusion, for the government to explore the blue economy and achieve the Vision 2030 and SDGs on food security and poverty reduction by 2030, efforts to promote commercial cage culture enterprises in the Winam Gulf must be bolstered, provided that cages are located in deep waters with low concentrations in specific areas and low stocking densities to avoid compromising the environment.

Effects of Changes of Lake Victoria Water Levels on Land Use Patterns, Covid-19 Pandemic and Food Security in Winam Gulf, Homa-Bay County, Kenya

The study was carried out on the Southern shore of Winam Gulf, Homa Bay County, Kenya. It was aimed at establishing the relationship among changes of Lake Victoria water levels, land use patterns and food security during the COVID-19 pandemic. Empirical studies involving ground point survey was used to determine the extent of spread of the back flow and vertical rise of the lake’s waters from five pier and nine beach survey points between July 2019 to October 2020. In-depth interviews and questionnaires were also used to collect data which were analyzed using descriptive statistics and Likert’s scale. The average variations of the extent of the back flow was approximately 294m while the vertical change in the water levels along the pier points was 1.03m. This led to submergence of the adjacent land use patterns and interfered with food security in the region. Coupled with the impacts of COVID-19 pandemic, majority (209) of the respondents substituted their meals and a quarter (79) of the them reduced their number of meals per day. A strong positive perception on the responses by the Government of Kenya and County Government Homa Bay towards addressing the pandemic with the Likert’s scale summative perception index of 381 very effective, 328 effective and 363 satisfactory were realized. The study recommends: observance and execution of environmental laws governing settlement on riparian lands, proactive compliance with the warnings and advice from the meteorological department, and adoption of alternative land use patterns.

Effects of Piers on Water Recession on the Southern Shores of Winam Gulf, Homa- Bay County, Kenya

Piers are important man-made water vessel landing facilities in lakes and seas. A study on the effects of piers on water recession was conducted on the Southern shores of Winam Gulf of lake Victoria, Homa Bay County in Kenya. It was conducted in three pier points namely Kendu Bay, Kowour/Homa Lime and Homa Bay. The study aimed at explaining a phenomenon whereby the Western side of the piers on the Southern shores of the gulf, having more water recession than on their Eastern side. This unique phenomenon has not been sufficiently researched on hence, instigated the research. It collected data on the length of recession at the sides of the piers, directions of water currents flow based on devised simple current simulator and empirical studies. Google map and Landsat map techniques were used for aerial data collection. Ground truthing was carried out to corroborate the findings of the aerial data based on physical ground measurement and observation. The result had it that the sides of the piers facing currents directly were more recessed than the opposite sides. Homa Bay pier had its Western side 38m shorter than the Eastern side which had only receded 2m. Kowuor/Homa Lime pier had its Northern side 32m more recessed than the Southern side. The drenching works at Kendu Bay pier at the time of study, made it impossible to accurately measure its sides under recession. However, it showed the same trend based on Landsat and Google maps data. The data were presented using photographs, ‘current rose,’ maps and diagrams.

Water Hyacinth (Eichhornia crassipes) infestation, interactions with nutrients, aquatic biota and a control weevil in Winam Gulf, Lake Victoria, Kenya

Lake Victoria just like many other lakes is affected by water hyacinth which resides in several bays for the better part of the year. This weed affects several economic activities of the locals and denies the government revenue every year from blue economic activities related to the lake. This paper explores the interaction of water hyacinth with biotic and abiotic factor and the efficiency of the introduced weevils in its control with an aim of advising on the best way to tackle the menace of the weed. Water quality samples were collected and compared from the time of water hyacinth arrival and sinking within Winam gulf. Water hyacinth was collected and damages resulting from the weevils as well as the number of weevils recorded. Fish samples were also collected using experimental gill nets. Water quality was analyzed for Ammonium, Soluble Reactive Phosphorus, Nitrates and Nitrates. Data was then analyzed using R- package. Results indicated that the weevils inhibits nutrient uptake by17% within the first four weeks, hyacinth increase the nutrient levels in the gulf almost three fold after decaying and sinking. Weevils also increased the sinking rate of water hyacinth through destruction of the petioles and leaves. There was a significantly higher fish numbers during the weed infestation than when the weed was absent. In conclusion water hyacinth impacts both biotic and abiotic factor and the weevils alone cannot be depended upon to eradicate the weed.

Distribution of arsenic, silver, cadmium, lead and other trace elements in water, sediment and macrophytes in the Kenyan part of Lake Victoria: spatial, temporal and bioindicative aspects

This is the first detailed report on the distribution of Ni, As, Sr and Ag in water, sediments and macrophytes from Lake Victoria, complemented with recent data on the heavy metals Cr, Cu, Zn, Cd and Pb. The study was conducted over an 11-month period at five sites in the Kenyan part of Lake Victoria: four sites in the Winam Gulf influenced by various anthropogenic pressures including a site near Kisumu City, and one in the main lake, perceived to have lesser direct anthropogenic influence. Compared with the main lake site, the water in Winam Gulf had significantly higher values for electrical conductivity and concentrations of dissolved components: organic carbon and bound nitrogen, as well as major and most trace elements. This contamination is also evident in surface sediments, which contained significantly higher levels of Cr, Zn, As, Ag, Cd and Pb compared with the main lake site. The mean levels of Cr, Cu, Zn, Ag and Pb exceeded probable effect levels at least at one of the gulf sites. The sediments at the Kisumu City site were classified as severely polluted with Cu (up to 259 mg/kg dw) and Pb (up to 1188 mg/kg dw). The sediment cores showed significantly higher levels of Cu, Zn, Ag, Cd and Pb in the surface (0–3 cm) versus subsurface (22–25 cm) layer at the Kisumu City site, indicating increasing pollution by these elements within the last 15 years. This is also the first report on trace elements in the emergent water plant Vossia cuspidata and submerged plant Ceratophyllum demersum from this lake. Even though the accumulation of most elements is comparable between C. demersum (whole plant) and V. cuspidata roots, the latter shows a better bioindicative potential. Contamination of the gulf with Ni, Cu, Zn, Ag, Cd and Pb is well mirrored in V. cuspidata roots. V. cuspidata strongly restricts the acropetal transport of trace elements, and hence using the shoots as fodder does not pose a risk to livestock.

Interaction of water hyacinth with biotic and abiotic factor and the biological agents efficiencies in its control in Winam gulf, lake Victoria Kenya

Lake Victoria just like many lakes across the world is effected with water hyacinth which resides in several bays for the better part of the year thus affect several economic activities of the locals and denies the government revenue every year from blue economic activities related to the lake. This paper explores the Interaction of water hyacinth with biotic and a biotic factor and the efficiency of the introduced biological agents (Neochetina eichhorniae and N. bruchi) in its control with an aim of advising on the best way to tackle the menace of the weed. Water quality samples were collected and compared from the time of water hyacinth arrival and sinking within winum gulf, this was divided in three phase, the hyacinth was collected and damages resulting from the weevils recorded. Fish samples were also collected using experimental gill nets and number recorded in Ms excel during the presence and absence of the weed. Water quality was analyzed for ammonium, SRP, nitrates and nitrates using SOP. The weevils were counted manually from each hyacinth collected and the data recorded. Data was then analyzed using R-data analysis at P<0.05 and post hock test to determine significance where applicable. Results indicated that the weevils inhibits nutrient uptake by17% within four weeks, hyacinth increase the nutrient levels in the gulf almost three fold after decaying and sinking and a notable interaction with biotic and a biota factor was also recorded. In conclusion water hyacinth impacts both biotic and a biotic factor and the weevils alone can not be depended upon to eradicate the weed.