• Analysis of Catchment Hydrologic Response Under Changing Land Use: the Case of Upper Molo River Catchment, Kenya.

      Kirui, Wesley K. (Egerton University, 2008)
      Change in land use has a direct effect in catchment hydrologic response. It is caused by human intervention to enhance and diversify their livelihood needs, and at the same time get economic benefits from the land resources. These interventions result in changes in surface runoff, soil erosion and sediment yield among others. If the change in land use is not well managed then it will affect the quantity and quality of water resources as well as production potential of the land. Based on this ground this study was formulated to investigate the effects of land use changes on catchment response, in particular surface runoff and sediment yield. Such a study required continuous hydrologic data such as stream flow and sediment yield for a number of gauging stations within the study catchment. However, most catchments in Kenya do not have adequate data to accomplish such study. In this study upper Molo River catchment in eastern Mau was used because of its consistent stream flow data. In this catchment there has been significant reduction in stream flow during dry season and flooding in the rainy season. This study investigated a modelling approach for predicting the changes in catchment response as a result of land use change. Soil and Water Assessment Tool (SWAT) was identified as suitable model and used to simulate the catchment response under different land use types. The input data used were digital elevation model (DEM), land cover, soils and rainfall. The DEM was processed in Arc View GIS and land cover maps derived from satellite image using ERDAS 8.5 imagine software. The land cover analysis results show that forest cover reduced by 48% as a result of increase in agricultural and settlement areas between the years 1986 to 2001. Simulation analysis carried out for 1986 and 1995 land cover maps, show an increase in surface runoff of 13.3%. In the simulation the data set was divided into two; 1980 to 1989 for calibration and 1991 to 2000 for validation. Conceptual parameters derived during calibration were used in the model to simulate streamflow for the two data sets and gave a Nash Sutcliffe coefficients of 0.87 and 0.72 respectively. The sediment yield values were 1.5t/ha for the calibration and 2.7t/ha for validation periods respectively. These results show insignificant change in the catchment response but demonstrated the effects of land use changes on catchment response. It is therefore concluded that land cover change of less 48% have insignificant change on catchment hydrologic response.
    • Analysis of Market Performance: a Case of ‘Omena’ Fish in Selected Outlets in Kenya.

      Kariuki, Maina B. Joel (Egerton University, 2011)
      The role and contribution of the fisheries sub-sector in Kenya cannot be underestimated. In particular, the contribution of Rastrienebola Argentea, commonly referred to as Omena, or Dagaa is increasingly being recognized and appreciated by several Government institutions and Non-Governmental organizations. Omena production is valued at 200 million dollars while its trade supports more than 2 million livelihoods. Different interventions by the government and the Non-Governmental organizations have resulted to increased production of Omena fish. However, increased production alone is not enough to effectively develop this industry. Information on the marketing functions and the efficiency with which these functions are carried out is lacking. In addition, distribution of costs and benefits along the Omena marketing chain is not known while fluctuations in supply affect price transmission between different markets. The main objective of this study was thus to assess the performance of Omena marketing in Kenya. The specific objectives of the study included: assessing the effectiveness of the Omena marketing channels; evaluating the price spreads along the different marketing channels; and to determine whether the spatially separated markets for Omena are integrated. Primary data was collected in two purposively identified regional markets in Kenya (i.e. Kisumu and Nakuru) while additional secondary data from the Nairobi region was included only for the purposes of analyzing market integration. Selection of markets was based on whether the markets are deficit or surplus regions for Omena. A multistage sampling procedure resulted to a total of 43 fishermen; 42 small scale processors; 20 wholesalers; 31 retailers; 32 domestic consumers; and 7 industrial consumers making a grand total number of 175 respondents. Questionnaires were adopted as the major tools of data collection using one-on-one interviews. To analyze the resultant data, the study utilized gross margin analysis and co-integration modeling. Results indicate that Omena marketing channels are to a large degree effective as it regards to meeting the consumption needs. However, results also indicated that longer marketing channels resulted not only to high costs and thus high retail prices; but also to lower returns to the fishermen. Further, the study identified that there is no integration amongst Omena markets in Kisumu and Nakuru and that a weak degree of integration existed between Kisumu and Nairobi. Information generated by this study is important in guiding policy makers to identify points of interventions as well as in designing effective and efficient Omena marketing channels.
    • Analysis of Market Performance: a Case of ‘Omena’ Fish in Selected Outlets in Kenya.

      Kariuki, Maina B. Joel (Egerton University, 2011)
      The role and contribution of the fisheries sub-sector in Kenya cannot be underestimated. In particular, the contribution of Rastrienebola Argentea, commonly referred to as Omena, or Dagaa is increasingly being recognized and appreciated by several Government institutions and Non-Governmental organizations. Omena production is valued at 200 million dollars while its trade supports more than 2 million livelihoods. Different interventions by the government and the Non-Governmental organizations have resulted to increased production of Omena fish. However, increased production alone is not enough to effectively develop this industry. Information on the marketing functions and the efficiency with which these functions are carried out is lacking. In addition, distribution of costs and benefits along the Omena marketing chain is not known while fluctuations in supply affect price transmission between different markets. The main objective of this study was thus to assess the performance of Omena marketing in Kenya. The specific objectives of the study included: assessing the effectiveness of the Omena marketing channels; evaluating the price spreads along the different marketing channels; and to determine whether the spatially separated markets for Omena are integrated. Primary data was collected in two purposively identified regional markets in Kenya (i.e. Kisumu and Nakuru) while additional secondary data from the Nairobi region was included only for the purposes of analyzing market integration. Selection of markets was based on whether the markets are deficit or surplus regions for Omena. A multistage sampling procedure resulted to a total of 43 fishermen; 42 small scale processors; 20 wholesalers; 31 retailers; 32 domestic consumers; and 7 industrial consumers making a grand total number of 175 respondents. Questionnaires were adopted as the major tools of data collection using one-on-one interviews. To analyze the resultant data, the study utilized gross margin analysis and co-integration modeling. Results indicate that Omena marketing channels are to a large degree effective as it regards to meeting the consumption needs. However, results also indicated that longer marketing channels resulted not only to high costs and thus high retail prices; but also to lower returns to the fishermen. Further, the study identified that there is no integration amongst Omena markets in Kisumu and Nakuru and that a weak degree of integration existed between Kisumu and Nairobi. Information generated by this study is important in guiding policy makers to identify points of interventions as well as in designing effective and efficient Omena marketing channels.
    • Are Peri-urban Mangrove Forests Viable? Effects of Sewage Pollution and Wood Exploitation on the Structure and Development of the Mangroves of Mombasa (Kenya)

      Mohamed, M.O.S (Vrije Universiteit Brussel, 2008)
      Acknowledging the increasingly prominent urban character of ecosystems globally, mangroves being no exception, and possible impediments to the viability of these ecosystems (i.e. the inherent capacity or ability to grow, develop or recover after disturbances), we adapt a system‟s approach to establish the viability of the peri-urban mangrove of Tudor creek in Mombasa, Kenya. Three important aspects of the peri-urban mangroves are assessed. These include (i) structural aspects (vegetation structure and regeneration), (ii) functional aspects (productivity) and (iii) human aspects (socioeconomics).
    • Artisanal Fisheries of Kenya's South Coast: a transdisciplinary case study of a socio-ecological system in transition.

      Okeyo, Benards (University of Bremen, 2010)
      This study examined the artisanal fisheries along the Kenyan south coast in the face of two major challenges: need to sustain the fishery resources on one hand and dependency of livelihoods of the coastal population upon the fishery resources on the other hand. At the Kenyan south coast a large number of people, mostly artisanal fishermen, have been displaced from their homesteads and fishing grounds to give way to other infrastructural developments - mostly tourism facilities. This has brought a severe competition for space and resources either for consumptive use by the local population as is the case of artisanal fisheries exploitation or non-consumptive use by the tourism development proponents. There is also the shift from local traditional management of the fishery to national government policy oriented management. This shift has evoked resentment by the local elders who for a long time used traditions, taboos and culture anchored on the belief systems to control exploitation of the fishery, relations amongst the fishers as well as conserve critical fish breeding and spawning grounds. These challenges have not been helped by the rapidly increasing population mostly due to immigration from the neighboring lands, lack of proper management policy derived in a participatory manner and not least, effluent disposal and pollution of inshore waters - fishing grounds for the artisanal fishers. The study was divided into two main components: the natural component that examined the biological dimensions of an artisanal fishery and socia-cultural studies. The latter looked at the various strategies of exploitation of the fishery, rules and institutions that presided over the fishery exploitation as well as mediated conflicts amongst the users. To realize the biological component of the study the nine fish landing sites of the selected study area were monitored over two years.These sites spread from the tourist area of Ukunda to the remote bay of Mkunguni down the Shimoni area. The distance between the first landing site on the north (Mwakamba) and last landing site towards the south (Mkunguni) was roughly 50 km. These sites were representative of the general artisanal fishery along the Kenyan south coast and fishing was done almost exclusively by artisanal fishermen using a limited number of relatively simple gears. All sites were visited by two observers twice a month. During each visit records of the total number of fishers, number of fishing vessels, gears used, weights of the fish catches; scientific and local names of the fish up to a genera or order level were captured. Other observations in regard to preparation of fishing expeditions, weighing and portioning of catches were recorded during the visit. Methods for socia-economic and cultural studies started by building of trust: on one hand between myself and my two assistants and on the other hand with the community. This was followed by the mobilization of participation of the artisanal fishers in the study aspects i.e. undertaking a sea spirits appeasing ceremony. Other tools involved the use of social science descriptors like use of PRA (participatory rural appraisal), digging into traditional knowledge systems, observations, semi-structured interviews, focus group discussions, oral histories, surveys and visualization techniques. Though listed differently, in many occasions they became handy simultaneously or sequentially and investigations took full advantage of all available opportunities.
    • Artisanal fishery analysis within the Mpunguti Marine Reserve (Southern Kenya): Gear-based management towards sustainable strategies.

      Gomes, Inez (Algarve University, 2012)
      The sustainable management of coral reef fisheries subjected to overfishing is challenged by the complex multi-species, multi-gear and poverty context of its artisanal fisheries. Worldwide coral degradation and overfishing are setting an increasing pressure to resource users and managers to reconsider current management practices and explore innovative strategies. This study was carried out in the Mpunguti Marine National Reserve, contiguous to the Kisite Marine National Park, a no-take coral reef fisheries closure, located off the south coast of Kenya in the Western Indian Ocean. We explored a gear based management approach by incorporating escape gaps (3 cm x 30cm) in traditional basket traps (malema) and comparing the catches with the traditional traps (controls). This gear based option exploits differences in selectivity among gear types to control catch composition, reduce the catch of juveniles and bycatch species, without compromising the fisherman's income. Of the 2060 fish sampled, we identified 93 species belonging to 26 families, during 213 sampling occasions. There was no significant difference in the total catch per unit effort (CPUE, kg/trap) between gated and traditional traps, but gated traps significantly (p <0.001) reduced the catch of non commercial fish (low-value, juveniles and narrow-bodied species). Moreover, for the most important local commercial species, the African white-spotted rabbitfish (Siganus sutor), the gated traps significantly increased the mean length of capture (by 13 %) and weight (by 32%) and decreased the proportion of catch under length at first maturity (Lmat) from 19.9% (traditional traps) to 3% (gated traps). Therefore, escape gaps did not reduce the catch of high value fish and decreased the catch of juveniles and narrow bodied coral reef herbivore species, increasing biodiversity, promoting sustainable practices and ecosystem health, without compromising fishermen's revenues.
    • Assemblage Structure of Decapod Crustaceans in the Malindi-Ungwana Bay, Kenya.

      Ndoro, Collins Kambu (University of Eldoret, 2013)
      Decapod crustaceans support both the artisanal and semi-industrial fisheries in Kenya and the Western Indian Ocean (WIO) region. Despite their commercial value, data on their assemblage structure is lacking in most of the WIO region but the data are important for stock management. This study aimed at bridging the data gaps by providing information on the seasonal variation in assemblage structure of decapod crustaceans in the Malindi-Ungwana Bay, Kenya. Samples were collected during a two-week experimental beam trawling survey under the South West Indian Ocean Fisheries Project (SWIOFP). Samples were collected during the northeast monsoon (NEM) and southeast monsoon (SEM) seasons. A total of 43 transects covering an estimated area of 546.4 nm2 were trawled in four depth zones (0-10 m, 10-20 m, 20-40 m and 40-100 m) in both seasons. Twenty (20) species of decapod crustaceans belonging to 7 families were sampled in both seasons. The species were distributed in the families; Penaeidae, Portunidae, Calappidae, Majidae, Matutidae, Palinuridae and Scyllaridae. The penaeid shrimps had a higher relative numerical abundance both in the NEM and SEM seasons of 89.3 and 85.3 %, respectively. Of the penaeid shrimps, Fenneropenaeus indicus, recorded the highest relative abundance of 57.6% during NEM and 41.5% during SEM season. Sex ratios of the penaeid shrimps were skewed towards females in the depth zones 2 (10-20m) and 3 (20-40m). Analysis of Similarity (ANOSIM) test indicated significant difference in total crustacean abundance (individuals/Km2) between the depth zones, (R=0.375; P=0.001; considering all seasons) but no significant difference between the seasons (R= -0.031; P=0.602; considering all depths). The mean species richness in the bay was higher during SEM than NEM season for all depth zones. Analysis of Variance (ANOVA) test indicated significant effect of depth (F=3.4773; df=2; P=0.044) but not season (F=0.5155; df=1; P=0.479) on species diversity. The crustacean assemblage structure in the bay was more influenced by depth profiles than seasonality. The shrimps, F. indicus, Penaeus monodon and the crab, Portunus sanguinolentus were mostly associated with depth zone 1(0-10 m), while the shrimps Metapenaeus monoceros, Penaeus japonius and the crab Ashtoret lunaris were closely associated with depth zone 2 (10-20 m). There was no clear species association with depth zone 3 and 4. Canonical Correspondence Analysis (CCA) indicated the influence of temperature, salinity, Secchi depth and dissolved oxygen in the bathymetric distribution of the crustaceans in the bay. It is recommended that seasonal distribution of the crustaceans be taken into consideration when developing crustacean fishery management plans for the bay. Additionally, survey in the bay should examine annual changes on assemblage structure in addition to biomass changes for species.
    • Assessing the impacts of environmental change on the hydrology of the Nzoia catchment, in the Lake Victoria Basin.

      Githui, Faith Wairimu (Vrije Universiteit Brussel, 2008)
      The main objective of this study was to assess the past and potential future environmental changes, and their impact on the hydrology of the Nzoia catchment. More specifically, the study has analyzed the historical climatic (1962-2004) and land cover changes (1973-2001) that have taken place in the Nzoia River catchment in Kenya, and the effect these have had on the hydrology of the catchment. It has also made use of land cover and climate change scenarios for the future to determine the potential effects these will have on the catchment. The Soil and Water Assessment Tool (SWAT) model was used to investigate the impact of land cover and climatic change on streamflow of the study area. The model was set up using readily available spatial and temporal data, and calibrated against measured daily discharge. The land cover changes within the watershed were examined through classification of satellite images and a land cover change model generated the land cover change scenarios for the year 2020. Climate change scenarios were obtained from general circulation models (GCMs) for the period 2010-2039 (i.e. 2020s) and 2040-2069 (i.e. 2050s). The climate change IPCC SRES scenarios A2 and B2 were selected. To this purpose, rainfall and temperature scenarios based on the GCMs CCSR, CSIRO, ECHAM4, GFDL and HADCM3 were superimposed on the calibrated SWAT model.
    • Assessing the Potential of Small-Scale Aquaculture in Embu District, Kenya using GIS and Remote Sensing.

      Mukami, Ngarari M. (Moi University, 2010)
      Site selection for aquaculture development is a complex task involving identification of areas that are economically, socially and environmentally suitable, which can also be available for aquaculture. Geographic information systems and remote sensing technologies, which facilitate the integration and analysis of spatial and attribute data from multiple sources, have been widely used for selecting suitable sites for different land uses. This study used these technologies to identify sites suitable for aquaculture development in Embu District and assessed its potential contribution to food security and economic development in the area. The study developed map-based site selection criteria, using soil quality, water availability and socio-economic factors. These criteria were then implemented, aquaculture potential sites identified, the total area estimated and the economic impact assessed. The study predicted that about 20% (9,563 ha) of the total arable area of 47,800 ha in Embu District is suitable for aquaculture development. The study estimates that if aquaculture is optimally combined with other existing land use activities, it can contribute over Kshs. 9 billion per annum to the district’s revenue. Comparing this with the current 7 ha under aquaculture, Embu District has potential for improving its economic status through aquaculture development. The study recommends that similar studies be carried out throughout the country so as to improve food security and wealth creation.
    • Assessing water quality in Lake Naivasha.

      Ndungu, Jane Njeri (University of Twente, Enschede, The Netherlands, 2014)
      Water quality in aquatic systems is important because it maintains the ecological processes that support biodiversity. However, declining water quality due to environmental perturbations threatens the stability of the biotic integrity and therefore hinders the ecosystem services and functions of aquatic ecosystems. This research aimed at studying the water quality in Lake Naivasha, Kenya. A myriad of environmental perturbations in Lake Naivasha’s ecosystem have transformed the lake from a clear to muddy eutrophic turbid state, which has resulted in a decline in ecological quality, impacting heavily on fish population and tourism. Though there has been regular data collection on water levels and fish catches, little has been done in monitoring the water quality dynamics in Lake Naivasha. The specific objectives were to assess the overall water quality status; establish the trophic status; assess retrospectively the water quality condition in the last decade; study effect of succession of fish community; and investigate the mechanisms that influence the water quality dynamics in Lake Naivasha. These objectives were achieved through coupling field measurements, geoinformation and earth observation, and system modelling. The field measurements were collected weekly from January to June and bi-weekly from July to November 2011 at seven locations in the lake. Water temperature, pH, conductivity, Secchi depth, and turbidity were measured insitu while others were analysed from water samples in the laboratory. Geoinformation and earth observation was used in the retrieval of chlorophyll-a concentration from June 2002 to June 2012 from Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) satellite images. The modelling objective was achieved using Delft3D Flow module to simulate the hydrodynamics in Lake Naivasha. Principal Component Analysis (PCA) and Cluster Analysis (CA) revealed spatial variability in physiochemical parameters, nutrients and main ions. Northern region, main lake, and Crescent Lake sectors of the lake were distinct. Water quality parameters association indicated that the quality of water is influenced by agricultural activities, and domestic effluent around Lake Naivasha. The Northern sector (close to rivers input) seemed to be influenced by agricultural activities. The North East sector of the Lake was dominated by domestic effluent and close association with the crescent lake which is influenced by natural mineral composition associated with its volcanic origin. This study also indicated that Lake Naivasha lies between eutrophic and hypereutrophic state. In comparison to previous water quality studies, this study showed that a further deterioration of the trophic status. Discriminant analysis (DA) of the trophic state indices (TSI) revealed that the trophic state was indeed heterogeneous with three distinct sectors which include: the northern part of the lake, the mid and southern sector, and the Crescent Lake. Graphical representation of the deviations of chlorophyll-a (TSI-CHL) and total phosphorus (TSI-TP) trophic state indices indicated that the lake was predominantly phosphorus limited (TSI-CHL > TSI-TP). Further scrutiny revealed that close to Mouth of Malewa (river input), North East (near the waste water treatment plant effluent discharge point and Kihoto informal settlement) and Kamere Beach (near Kamere informal settlement), the turbidity constituents were mainly dominated by sediments or other organic matter rather than chlorophyll-a (TSI-CHL < TSI-SD (SD=Secchi depth )). In Crescent Lake, the TSI-CHL exceeded the TSI-SD (TSI-CHL > TSI-SD) which was an indication of the presence of algae species with a more filamentous or colonial structure than in the rest of the lake. This study affirms the possibility of retrospective analysis of spatial variations and temporal trends in chlorophyll-a concentration’s using MODIS-Aqua satellite data, and therefore provide data at times when routine ground measurements do not exist. The existence of a large inter-annual spatial variation in chlorophyll-a concentration over the lake was evident particularly in the monthly composite maps. The results portray a large temporal variability which was partly caused by seasonal influences such as climate (rainfall) and seasonal agricultural practices. This was also evident in the long-term trend variations that correlate to the lake level, which could explain dilution and concentration effects.
    • An Assessment of Domestic Water Consumption Discrepancies Between Commercial Farms and Majengos Along South Moi Lake Road, Lake Naivasha, Kenya.

      Heemink, Barbara (University of New Mexico, 2005)
      The overall intent of this professional project was to provide a preliminary assessment of domestic water consumption discrepancies between commercial farms and majengos at Lake Naivasha, Kenya. As this issue of concern had not been previously studied, pre-determined factors known to incur domestic water consumption discrepancies were utilized, in relation to a regulatory setting, with the purpose of illustrating the viability of this problem. Lake Naivasha is a freshwater lake in the Rift Valley Province of Kenya, Africa. Over the last fifteen years, the horticulture and floriculture industry at Lake Naivasha has steadily grown, with the most intense development occurring in the late 1990's. The rapid growth of the commercial horticulture and floriculture industry, compounded by Kenya's high unemployment rate, has resulted in an increase in the populace in the region immediately surrounding Lake Naivasha, based on perceived employment opportunities to native Kenyans with these farms. The problem addressed in this professional project is that there are discrepancies in meeting the basic human domestic water consumption requirements (BWR) of 50 liters per person per day (Up/d) between residents of majengos and commercial horticulture and floriculture farms at Lake Naivasha. The BWR are those requisite for subsistence purposes and provided in sufficient quantity and quality needed to sustain a healthy human life. The primary purpose of this professional project was to verify that social considerations, inclusive of water supply infrastructure, community commonalities, and structured representation; the nature and extent of surface water use; and surface water access, distance, and retrieval and transportation methods, and alternative sources of domestic water supply are direct factors attributing to discrepancies in domestic water consumption such that residents of majengos at Lake Naivasha were not meeting the BWR of 50 Up/d, whereas commercial farms were consuming domestic water in excess of the BWR. The secondary purpose of this professional project was to determine if the current land tenure system and the water resource legislative framework promoted the incurrence of the above factors resulting in discrepancies in meeting the BWR between residents of majengos and commercial farms. A field-based study was completed in the region situated within approximately 2 km of Lake Naivasha's southern shoreline. The study area incorporated 24 of the acknowledged 38 commercial farms reliant solely on surface water at Lake Naivasha and four of the seven majengos documented at Lake Naivasha. The results of the field-based study, augmented by cited literature and available documents, indicated there were discrepancies in domestic water consumption quantities between the two stakeholders due to the absence of municipally and community-owned and/or operated water supply infrastructure, and the absolute absence of commonality between majengo members and commercial farms with regards to structured representation, economic and social status, employment types, standard of living, the extent and nature of surface water use, surface water access, distance, and retrieval and transportation methods, and alternative sources of domestic water supply water. Furthermore, the determination was made that commercial farms were consuming domestic water at quantities greater than 50 Up/d. There were insufficient usable data to empirically confirm that members of majengos were consuming domestic water at quantities less than the BWR. The determination was made that there is a direct correlation between the land tenure system and water resource legislative framework and the noted discrepancies in domestic water consumption between the two stakeholders. Specifically, components of the current land tenure system and water resource legislative framework incur discrepancies between majengo members and commercial farms with regards to the extent and nature of surface water use, surface water access, and alternative sources of domestic water supply water.
    • An Assessment of Nutrient Loading, Eutrophication and Plankton Dynamics in three Marine Tidal Creeks, Kenya: Port Reitz, Mtwapa Creek And Funzi Bay.

      Mvoyi, Chihenyo (University of Nairobi, 1999)
      Coastal marine eutrophication is recognised as a worldwide problem. On a global scale, it is now estimated that the input of nutrients especially various forms of nitrogen and phosphorus, to marine ecosystems from human sources via rivers are equal to or greater than, the natural input. The proposed study aims at assessing the eutrophication status of creeks to determine effects of nutrient loading on these ecosystems. This aim will be achieved by assessing the forms, concentrations and ratios of nitrogen and phosphorous as principal nutrients and how they affect rates of production and both phytoplankton and zooplankton compositions. The creeks have been chosen due to differences in nutrient loading. Port Reitz and Mtwapa creeks will be compared to Funzi bay, a relative pristine ecosystem. Sampling in these areas will be done taking into consideration, both point and non-point sources of anthropogenic nutrient loading. Physico-chemical parameters that will be analysed at each site include temperature, conductivity, dissolved oxygen and salinity. The various forms and concentrations of Nitrogen and Phosphorous will be analysed using various methods described for the analysis of nutrients in tropical seawater. Various phytoplankton and zooplankton compositions will be counted and analysed statistically using the Shannon-weaver method. The effects of nutrients on primary production, phytoplankton and zooplankton abundance will be determined in a bid to assess eutrophication and nutrient loading effects to productivity of these ecosystems. The information obtained during this study shall contribute significantly to the formulation of pollution/eutrophication control procedures as well as a basis for future research.
    • Assessment of Pesticide and Heavy Metal Residues in Tilapia Fish From Machakos and Kiambu Counties, Kenya.

      Omwenga, Isaac Mokaya (Department of Public Health, Pharmacology and Toxicology, Faculty of Veterinary Medicine,University of Nairobi, 2013)
      Exposure to pesticides, heavy metals and other chemical residues cause harmful effects; they can cause injury to human health as well as to the environment. Humans take up these chemicals through skin absorption, respiration and ingestion of contaminated food. Among all foods, fish is one of the main sources of chemical contaminants although fish products account only for about 10% of diet or less. The present study was conducted in Kiambu and Machakos counties with objectives of determining the concentration levels of pesticides and heavy metals in edible parts of fish from inland fish farms, The dietary intake of pesticide and heavy metal was also estimated and compared with acceptable daily intakes of the World Health Organization (WHO) guidelines so as to assess their potential health hazard. A total of two hundred and thirty tilapia fish samples (n= 230) were collected from Kiambu and Machakos counties in the months of September and October 2011. Following wet digestion, the levels of lead and cadmium were determined in muscle, liver, gonad and brain of tilapia fish using Atomic Absorption Spectrophotometer (AAS) fitted with cadmium and lead lamps set at their respective wavelengths. To evaluate organochlorine concentration, fish samples were extracted, cleaned and analyzed using Gas Liquid Chromatography (GLC) fitted with Electron Capture Detector (ECD). The data was subjected to descriptive statistics and Analysis of Variance (ANOVA) to test levels of significance at 95% confidence limit using Statistical Analysis Software (SAS) 9.0 version. Significance was noted at P< 0.005. In Kiambu county, mean lead levels (x ± s.d) in brain, liver, gonad and muscle were 31.31 ± 28.27, 17.33 ± 20.64, 16.62 ± 15.42 and 3.78 ± 2.22 ppm respectively against `the benchmark xv value of 0.5ppm.The average cadmium levels (x ± s.d) in the brain, liver, gonad and muscle were 7.25± 6.59, 5.35 ± 6.12, 3.35 ± 4.16 and 1.66 ± 2.48 ppm respectively against the benchmark level of 0.05ppm.However, only positive samples were considered. Out of the total number of samples analyzed, only 40% were positive for lead and cadmium in Kiambu county and 34 % in Machakos County. In Machakos county, mean lead levels (x ± s.d) in the brain, liver, gonad and muscle were 30.40±20.56, 7.88 ±7.25, 13.29±14.28 and 12.22±22.96 ppm respectively against the benchmark level of 0.5ppm.The average cadmium levels (x ± s.d) were 3.91±5.84, 2.90±3.58, 1.25±1.38 and 1.12±1.13ppm respectively against the benchmark level of 0.05ppm. The Organochlorines exhibiting the highest concentration (x ± s.d) were o,p ‘-DDT with a mean of 2.098±4.097 μg Kg-1 followed by p’p-DDD 1.684±3.666 μg Kg-1 in the brain tissues. This was followed by p’p-DDD in muscle at 0.916±1.287 μg Kg-1 and pp-DDT at 0.916±1.916 μg Kg-1. Machakos County had p,p’-DDT at a concentration of 0.158 μg Kg-1 ,p,p’-DDD had 0.097 μg Kg-1 and p’-DDT had a concentration of 0.016±0.016 . Statistically, there was no significant difference in the tissues analyzed for the concentration of Pb in the two counties since pr/t/>0.05. Cadmium concentration in the gonad had a significant difference between Kiambu and Machakos County since pr/t/=0.05.The brain, liver and muscle did not show any significant difference in the concentration of Cadmium between the two counties since pr/t/ >0.05 . The results of the current study indicate the presence of relatively high levels of lead and cadmium above permissible limits in fish from the study areas and recommend controlling industrial and agriculture effluents into surface water and proper sitting of ponds to minimize the risk of contamination of farmed fish by pesticides and heavy metal. However it was noted that the number of samples that were positive with regard to the presence of all residues was small compared to the total number of samples analyzed.
    • Assessment of Pollution and Prediction of Environmental Risks of Organochlorine Pesticide Residues on Aquatic Communities in Lake Naivasha, Kenya.

      Njogu, Paul Mwangi (Jomo Kenyatta University of Agriculture and Technology, Nairobi (Kenya), 2011)
      Anthropogenic activities in the Lake Naivasha catchments pose serious environmental threats to sustainable freshwater ecosystem management. The future of the lake hangs on the balance of economic exploitation and sustainable watershed conservation. The current growth experienced in the chemical intensive flower industry, human settlements and power generation have led to chemical pollution, wetland reclamation and increased water abstraction volumes, which threaten the existence of the water body. Chemical drift during spray and washing of agrochemicals during the rainy season add the chemicals to water bodies. This study reports the findings of an environmental pollution assessment and environmental risks assessment posed by organochlorine pesticide residues and their metabolites in the Lake Naivasha basin during the period between 2008 and 2009. The objective of the study was to assess environmental pollution in reference to heavy metals, organochlorine pesticides in Lake Naivasha basin and to predict environmental risks of organochlorine pesticides on aquatic communities. Primary data was acquired through interviews, observations and sample whereas secondary data was obtained from published information. The data was analyzed statistically at p = 0.05 confidence level using significant T-Test, ANOVA and Dixon’s test. The concentrations of lead (Pb), cadmium (Cd), nickel (Ni), zinc (Zn), copper (Cu), p, p’- DDT, p, p’- DDE, p, p’- DDD, heptachlor, heptachlor epoxide, lindane, aldrin, dieldrin, endosulfan and methoxychlor in water column and three fish species; Tilapia, (Oreochromis leucosticus), Common carp, (Cyprinus carpio) and Mirror carp, (Cuprinus spectacularlus) from Lake Naivasha, Kenya were determined.
    • Assessment of the effectiveness of the regulatory regime in controlling the effects of oil pollution on Kenya's coastal and marine environment.

      Ohowa, Boaz Ogola (Dalhousie University, 2004)
      The Kenya coast is part of the major tanker route that stretches along the East African coast, running from the Middle East round the Hom of Africa to other parts of the world. The major Kenyan port, Mombasa, handles a substantial number of ocean-going ships (including oil tankers) and other smaller vessels, in addition to having other installations that deal with oil such as refineries and power generators. This raises the prospect of chronic oil pollution in the coastal and marine environment, which could have negative impacts on the natural resources thereof. The paper presents an assessment of the effectiveness of the regulatory regime in the management of marine oil pollution. It provides an overview of the natural resources, and their susceptibility to oil pollution. They include mangrove communities, coral reefs, seagrass communities, fisheries, sandy substrates and the water column, with special emphasis on the surface microlayer of the latter given its high propensity to accumulate the hydrophobic petroleum hydrocarbon pollutants. An overview of Kenya's policies/legislation, together with regional and international agreements, treaties and protocols relating to marine oil pollution management is also presented. Some of the most commonly used indicators of effectiveness in oil pollution management are reviewed. They include surveys of beached oiled birds, monitoring of stranded tar balls along beaches, aerial surveillance and space-borne remote sensing. A comparative analysis of some effective environmental regimes is provided, having specific regard to marine oil pollution. The problem of chronic oil pollution in Kenya's coastal and marine environment is assessed from the viewpoint of the potential sources in terms of its magnitude. The capacity of Kenyan institutions with regard to marine oil pollution management is also analysed. From the reviews and analyses, it emerges that although Kenya could be having the right policies and regulations in place to deal with the management of marine oil pollution, the complete set of instruments by which policy effectiveness can be evaluated seems to be lacking. Instruments can be defined strictly as the resources that can be used by or through the government to attain policy objectives. These include staff, administrative structures, financial means, training and awareness raising. In light of this, the paper ultimately distils some key recommendations that Kenya could adopt in an effort to enhance the effectiveness of the existing marine oil pollution regulatory regime. Thus the use of tar ball monitoring (quantitative measurement of stranded beach tar) as a relatively cost-effective indicator of the state of the coastal marine environment with regard to petroleum pollution is recommended. Other recommendations are conducting educational campaigns to vessel operators on the meaning and consequences of oil spills, and the prospect of using satellite data subject to the availability of some of the instruments such as financial means and training.
    • An Assessment of the Kenyan Coastal Artisanal Fishery and Implications for the Introduction of FADs.

      Mbaru, Emmanuel Kakunde (Rhodes University, 2012)
      The marine fishery in Kenya is predominantly small-scale and artisanal with about 11,000 fishers intensely fishing near shore coastal reefs using minimally selective fishing gears. A large majority (88%) of fishers use outdated equipment such as basket traps, beach seines, hand lines (hook and lines), fence traps, gillnets, spearguns and cast nets. Handmade canoes propelled by paddles (kasia) or sail power are used to access offshore waters, while only a few fishers have motorized boats. Although fishers along this coast know and express the potential of offshore fishing, most of them are disempowered and unable to access any of the largely untapped offshore pelagic resources. Using a unique dataset from four distinct coastal areas: Funzi-Shirazi bay area, Diani-Chale area, Mombasa-Kilifi north coast area and the Malindi-Ungwana bay area, containing species level length frequency catch data from the multi-gear and multi-species fishery, abundance of specific species, gear use comparisons in various regions, catch per unit effort and total catch estimate over a nine year period (2001 – 2009) were evaluated. Despite high diversity in the fishery, five species (Lethrinus lentjan, Siganus sutor, Leptoscarus vaigiensis, Lethrinus harak and Parupeneus macronemus) represented over 75% of the catch. A total of 11 legitimate gears were observed in this coastal artisanal fishery with basket traps (42%) being the most popular. Fishers along the Mombasa-Kilifi area predominatly used beach seines while those in Diani-Chale, Malindi-Ungwana bay and Funzi-shirazi bay predominaltly used spearguns, gillnets and basket traps, respectively. Apart from gillnets, a general declining trend for most of the gear types was observed since 2004. Beach seines recorded the lowest (20.9~c0.2 cm) mean length while gillnets recorded the highest (34.2~c0.3 cm). The highest catch (~26,000 metric tons) came in 2001 and the lowest (~15,000 metric tons) in 2005. The highest number of fishers was observed in 2008 while 2009 recorded the highest (4.8~c2.3) mean number of hours per outing. The mean annual CPUE per region ranged from (1.5 kg.fisher-1.hr-1) in Diani-Chale to (1.0 kg.fisher-1.hr-1) in Malindi-Ungwana bay. Making use of questionnaire data, the attitudes towards offshore fishing strategies, FADs in particular, were evaluated. Some communities (about 25% in every location) were not even aware of FAD fisheries. With the imminent introduction of a FAD fishery in Kenya, it was concluded that, for this fishery to realize its full potential, training on FAD fishing techniques has to be done. Finally, effective management is necessary if small-scale fisheries are to continue providing food security for many poor coastal communities. Gear-based management in Kenya, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in near shore fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. This thesis seeks to identify ways in which the Kenyan artisanal fishery can be sustained and managed from within coastal communities, giving them the resources and education to effectively improve their lives. The introduction of a offshore FAD fishery and hence access to offshore pelagic species provides an opportunity to not only alleviate pressure on coastal resources but also to empower coastal communities and contribute to the growth of Kenya’s national economy as a whole.
    • Assessment of Water Quality and Fish Producivity in Three Undrainable Reservoirs of Naromoru, Nyeri County, Kenya.

      Ndiwa, Titus Chemandwa (Kenyatta University, 2011)
      Naromoru is a semi-arid area located on the leeward side of Mt. Kenya, and has more than 15 small sized reservoirs constructed to provide water for livestock, irrigation and domestic use. To increase their usefulness, some reservoirs have been stocked with fish, even though no studies have been carried out to establish their suitability and potential for fish culture. This study therefore aimed at assessing the water quality, fish food availability and fisheries productivity of three undrainable reservoirs of Naromoru, selected on the basis of their location, accessibility, size and fish availability. The study was carried out between September 2008 and February 2009. Water quality was determined by assessing the physical (temperature, water depth, transparency) and chemical (pH, dissolved oxygen, electrical conductivity and total dissolved solutes) characteristics. Water samples were also collected and concentrations of the major anions (bicarbonates, sulphates and chloride), cations (potassium, calcium, magnesium and sodium), heavy metals (copper and lead) and nutrients (nitrates and phosphates) measured using Atomic Absorption Spectrophotometer (ASS). Phytoplankton communities were sampled by filtering 15 litres of water through 0.063~km mesh plankton net, and their relative abundance, species composition and diversity determined. Similarly, zooplanktons were sampled by filtering 10 litres of water through 100~km, while benthic invertebrates were sampled using an Ekman grab sampler and their species composition, diversity and relative abundances determined. Fish were caught by seine and gill nets, identified and measured for standard lengths (cm) and weights (g). Length and weight measured were used in analysis of relative condition factors and length-weight relationship. Data was analysed by Kruskall-Wallis test, principal component analysis and Mann-Whitney test. Results showed that physical and chemical characteristics fell within the recommended guidelines for fish culture in all the three reservoirs, with the exception of water transparency, which measured 7.4±0.11cm at Kianda Dam. Lusoi Dam had the lowest water quality status with pH, TDS and conductivity measuring 9.6±0.05, 833±35.3mgl-1 and 1283±48.1~kScm-1, respectively. Concentration of heavy metals in the dams was generally low. The three reservoirs had abundant fish food supply, with phytoplankton dominated by the blue green algae, Microsystis aeruginosa while zooplanktons were dominated by rotifers and copepods. Cladocera only occurred in Kianda Dam. Benthic invertebrates were similarly abundant dominated by chiromids and oligochaetes. The fish had good relative condition which ranged from 1.7 to 1.9. A highly significant length-weight relationship was obtained with an R2 value of 0.9908, 0.9708 and 0.9495 at Gathathini, Lusoi and Kianda Dams, respectively, indicating an allometric fish growth. Fish productivity in the dams ranged from 47±29.6g/m2/hr to 259±150.2g/m2/hr. These results show that the undrainable reservoirs of Naromoru are generally suitable for fisheries production, even though management interventions are needed to deal with pollution problems and fish seed quality in order to achieve maximum fish productivity.
    • Asteroidea of Mombasa Marine National Park and Reserve.

      Eekelers, Dirk (Vrije Universiteit Brussel, 1970)
      Biodiversity, abundance, feeding preference and habitat data on an assemblage of shallow water, coral-reef starfish (Asteroidea) were gathered over four months at Mombasa National Marine Park and Reserve. M1VINP&R contain a fringing reef and are situated between Mombasa town and Mtwapa creek on the East African coast of the Western Indian Ocean. It has not been known to carry an outbreak of the corallivorous crown-of-thorns starfish (Acanthaster planci) and its coral cover is well developed. Specimens required primarily for identification were collected by means of circlesampling, time transects and random searches. In addition, a selection of large and small, dead coral slabs were overturned and cryptic specimens located beneath these slabs were collected. Data for the abundance investigation was collected by means of 30' time transects in the inner and outer-reef. In the shallow inner-reef the surveys were done using snorkelling equipment while investigation of the outer-reef was done with the use of SCUBA gear. Additional investigation was done to obtain information about the habitat preferences of the species. When doing the transects for habitat, abundance or species presence surveys, species were turned over to detect the food preference of the animals. The identifications of the species were done under supervision of Prof. Jangoux at the laboratory for Oceanology, ULB Brussels. The finding of Choriaster granulatus, Fromia monilis, Neoferdina kuhli are new records for East Africa while Halityle regularis, Pentaceraster horridus, Pentaceraster tuberculatus and Euretaster cribrosus represent new records for the coast of Kenya It was found that MMNP&R carries a rich and diverse asterooid fauna but the imperfectness of the time transect method especially in regard to cryptic species indicates that additional species are still to be located. Of the 18 starfish species found in M1VINP&R, 6 (Choreaster granulatus, Fromia monilis, Gomophia egyptica, Linclda multiflore, Nardoa variolata and Neoferdina kuhli) were located only in the outer-reef. An additional seven species (Halityle regularis, Pentaceraster horridus, P. mammillatus, P. tuberculatus, Leiaster coriaceus, Asterina burtoni and Euretaster cribrosus) were found only in the inner-reef. Some specimens were located in the inner as well as the outer-reef (Acanthaster planci, Culcila schmideliana, Protoreaster lincki, Linckia laevigata and L. guidingii), though a preference for one of the reefs was obvious for some of these species. None of the species were found in intertidal areas. While, Acanthastar planci, Fromia monilis, Gomophia egyptiaca, Linckia multiphora, Neoferdina kuhli and Nardoa variolata were sometimes found at the base of the reef slope, they were never observed on the sea floor away from the reef The preceding species can be regarded as coral-reef species and their distribution differs from that of species such as Choreaster granulatus and Culcita schmideliana that were also found in the deeper off-reef waters in the MNP&R region or Pentaceraster spp and Protoreaster lincki who were manly found in the inner-reefs sea grass beds. The observation that most species (all except one) of , starfish found on MMNP&R belong to the order of the Valvatida corresponds with the results of other investigations done in the tropical regions, and a general increase in relative significance of this order toward the tropics is noted. The asteroids found on MMNP&R showed some inter-specific variation with respect to die but most species appeared to feed on in the inner-reef there is a general increase of the total number of starfish from the park to the reserve. This is most likely an effect of the full protection status of the park in regard to fishery, which is reflected in a higher density of the main predator of the starfish (the triggerfish Balistapus undulatus) at the park. In the park's outer-reef a dominance of Linckias was noted;, these species are well known for their extraordinary regenerative capacities and their autonomous asexual reproduction capabilities. These qualities surely increase their surviving opportunities in an area with high predation pressure. The asteroid communities of MMNP&R were clearly adult-dominated, although the juveniles of these species might complete their early development under boulders and are for that reason difficult to detect with the used method. Still, many workers who have studied coral reef asteroid populations have noted the adult-dominated size structure of these populations.
    • Bioaccumulation of Trace Metals in Biota (Algae and Chironomids) from Kenyan Saline Lakes (Bogoria and Nakuru): Evaluation and Verification of Two Compartment Toxicokinetic Models.

      Muohi, Ann Wairimu (Carl von Ossietzky Universität Oldenburg, 2007)
      This study was carried out to assess the suitability of various aquatic biota particularly those associated with some Kenyan Saline lakes, as biomonitors of trace metals. The study also aimed at evaluating the use of two-compartment and logistic regression models as predictive tools in assessment of environmental quality in the specific ecosystems. Experimental organisms namely, algae (Arthrospira fusiformis) and chironomids (Lepotochironomous deribae) among others, were obtained particularly from, Lakes Bogoria and Nakuru. Environmental sediment samples were also collected from the lakes, for a survey of the pertinent elemental background levels. Using the obtained organisms, exposure and depuration experiments were set up at The Nakuru Municipal/L. Nakuru National Park laboratory and at The School of Biological Sciences in the University of Nairobi, Kenya. Experimental samples were stored in a freezer at -20~'C and were later dried at 80~'C, before transportation to the Aquatic Ecology Laboratory in The University of Oldenburg, Germany, for chemical and data analysis. In the chemical analysis, aliquots of 10 mg samples were digested in 2 ml safe-lock Eppendorf reaction tubes for 3 hours at 80~'C with 100 ~kl HNO3 (65% suprapure). Cadmium, Cu and Pb elements were analysed using a Varian SpectrAA 880 Zeeman instrument and a GTA 110 graphite tube atomiser. Zinc was analysed using an air-acetylene flame (Varian SpectrAA-30, deuterium background correction) and a manual micro-injection method (100 μl sample volume). All metal concentrations in biological tissues are reported in ~kg g-1 dry weight (dw). For validation of the method, Certified Reference Materials (CRMs) namely BCR-CRM No.279 Sea Lettuce (Ulva lactuca) and Standard reference Material 1572 Citrus leaves, from the Commission of The European Communities (Community Bureau of Reference), and TORT-2 Lobster hepatopancreas and CRM 278R Mussel tissue (Mytilus Edulis) from the National Research Council of Canada were analysed using the same methods. Results obtained were in agreement with the certified values at 95% confidence level. Statistical analysis and modelling were done using SYSTAT version 10 and EXCEL programmes.
    • Bioavailability of Sediment-Bound Heavy Metals along the Coast of Eastern Africa and Evaluation of Metal Concentrations along the Trophic Hierarchy.

      Okuku, Eric Ochieng (Vrije Universiteit Brussel, 2007)
      Heavy metals pollution of near shore marine ecosystems is a growing problem in most of developing countries. Unfortunately, total concentrations of metals in sediments have been shown not to be fully worth relying upon as a good predictor of the bioavailability and toxic effects of metals to the biota. Furthermore, besides anthropogenic sources, natural processes such as weathering of parent materials can contribute significantly towards total metal concentrations in the sediments. Generally metal fractions of natural origin are relatively less accessible to the biota compared to metals from anthropogenic sources. Therefore, in order to accurately evaluate the possible biological effects of trace metals in sediment, additional information on mobilization capacity and bioavailability are required. The results presented in this study showed that levels of total metals in sediments from locations along the coast of Eastern Africa were in some cases comparable to heavily polluted areas around the world. But further analysis revealed that heavy metal content in this lowly industrialized region was actually coming from natural sources. The study also showed that sediment-bound metals (especially at rural locations) were generally not easily available to the local biota. Interlocations comparisons of metal concentrations in the biota showed higher values around polluted urban areas compared to rural locations. In the case of marine plants, the study showed that the labile metal fraction was a better predictor of bioavailability, while in for animal species both labile and EDTA extractable fractions were found to best predict bioavailable metals to this group of organisms. The study approach which involved analysis of metal concentrations in the biota, in sediments and different types of sediment metal extraction procedures and the calculation of metal enrichment factors in sediments, proved to be able to delineate metals of natural and anthropogenic origin.