School of Natural Resources and Environmental Studies

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Ecology and Management of Lake Naivasha, Kenya, in Relation to Climatic Change, Alien Species' Introductions, and Agricultural Development
(Environmental Conservation; Cambridge Journals, 1990) Harper, David, M.; Muchiri, Mucai; Mavuti, Kenneth, M.
Lake Naivasha is an important freshwater resource for Kenya's foreign-currency-earning agriculture and tourism, and for water-supply. It has always experienced extensive water-level fluctuations as a consequence of irregular rainfall patterns that are affected by continental-scale climatic events, and its communities — particularly of aquatic plants — were adapted to these changes.
Organochlorine and organophosphorus pesticide concentrations in water, sediment, and selected organisms in Lake Naivasha (Kenya)
(Kluwer Academic Publishers, 2002) Muchiri, Muchai; Gitahi, S. M.; Harper, D. M.; Tole, M. P.; Ng’ang’a, R. N.
The status and future of the Lake Naivasha fishery, Kenya
(Kluwer Academic Publishers, 2002) Muchiri, Mucai; Kundu, Rodrick; Taylor, Andy; North, Rick; Harper, David M.; Bailey, Roland; Hickley, Phil
Lake Naivasha is a freshwater lake situated in the eastern rift valley of Kenya. Only five species of fish are present, all of which have been introduced. They are Oreochromis leucostictus, Tilapia zillii, Micropterus salmoides (largemouth bass), Barbus amphigramma and Poecilia reticulata (guppy). The first three of these form the basis of an important gill net fishery and bass are also taken by rod and line for sport. Barbus are occasionally caught by dip net. Actual and potential yields for the Lake Naivasha fishery are discussed and the fishery is shown to be under-performing. The feeding regimes of the commercially exploited fish were examined in the context of available food supply, in particular the benthic fauna. Small bass depend heavily on Micronecta and large bass mostly take crayfish. Detritus predominates in the diet of Oreochromis leucostictus and Tilapia zillii but the former also eats algae and the latter, Micronecta and macrophyte. Various food resources, especially the benthos, appear to be under-utilized and so it is possible that further species could be introduced to enhance the commercial fishery.
Environmental assessment of the East African Rift Valley lakes
(Aquatic Sciences, 2003) Odada, Eric, O.; Olago, Daniel, O.; Bugenyi, Fred; Kulindwa, Kassim; Karimumuryango, Jerome; West, Kelly; Ntiba, Micheni; Wandiga, Shem; Aloo-Obudho, Peninah; Achola, Pius
An assessment of the East African Rift Valley lakes was initiated by the United Nations Environment Programme (UNEP) with funding from Global Environment Facility as part of the Global International Waters Assessment (GIWA). The purpose of GIWA was to produce globally comparable assessments and examine stresses on international waters: marine, coastal and fresh; surface and groundwaters. The assessment of the East African Rift Valley lakes was undertaken from the perspective of water quality and quantity, associated biodiversity and habitats, their use by society and societal causes of the regionally identified issues and problems. Assuming intrinsic values of aquatic ecosystems, the assessment of social perspective focused on human use of water and considered the incremental costs of measures to encourage sustainable development. The assessment identified the major concerns facing the East African Rift Valley lakes. By and large, pollution and unsustainable exploitation of fisheries and other living resources emerged as critical concerns attributable to human activities. East Africa has a very high concentration of humans and economic activities. Pollution is from uncontrolled discharge of wastes directly into the lakes. Unsustainable exploitation of fisheries and other living resources is caused by over-fishing, destructive fishing practices, and introduction of non-native species that affect the composition of the native communities, resulting sometimes in the collapse of certain species and dominance by resilient ones. Loss of biodiversity also was identified as a major concern; and the issues of excessive by-catch and discards are also relevant. Trawling using undersized mesh-nets for target species and indiscriminate fishing gear or poison is serious, in most cases resulting in indiscriminate catches, including juvenile fish. Given the transboundary nature of the issues identified in this assessment, appropriate multilateral policy and institutional arrangements need to be established in East Africa to address the main concerns of these large lakes. Riparian countries must pay attention to the regional management of these transboundary water bodies, and appropriate planning of human population sizes and their settlement, land-use and waste disposal to control pollution. Although East African lakes contribute relatively little emission of greenhouse gases, there is a need to reduce the rate of deforestation and even restore cleared areas since forests serve as sinks of greenhouse gases towards mitigating adverse climatic changes.
Biological diversity of the Yala Swamp lakes, with special emphasis on fish species composition, in relation to changes in the Lake Victoria Basin (Kenya): threats and conservation measures
(Biodiversity & Conservation, 2003-05) Aloo-Obudho, Peninah
During the second half of the last century, the Lake Victoria ecosystem has undergone drastic ecological changes. Most notable has been the decline in the populations of many endemic cichlid fishes. The lake has lost nearly 200 haplochromines and one tilapiine, Oreochromis esculentus. The above changes have been attributed to effects of species stocking and, in particular, from predation pressure by the introduced Nile perch, Lates niloticus. Other factors that have led to the decline of the endemic species include intensive non-selective fishing, extreme changes in the drainage basin, increased eutrophication, and the invasion of the lake by the water hyacinth, Eichhornia crassipes. However, the remnants of some species that had disappeared from Lake Victoria occur abundantly in the Yala Swamp lakes (Kanyaboli, Sare and Namboyo). This paper discusses the biodiversity of the swamp and the three lakes and gives suggestions for their conservation.
Habitat degradation and subsequent fishery collapse in Lakes Naivasha and Baringo, Kenya
(2004) Muchiri, Mucai; Hickley, Phil; Boar, Rosalind; Britton, Robert; Adams, Chris; Gichuru, Nicholas; Harper, David
Lakes Naivasha and Baringo in the eastern Rift Valley of Kenya are shallow, freshwater lakes that are subject to major fluctuations in water level and suffer from habitat degradation as a consequence of riparian activity. Lake Naivasha is approximately 160 km2, is bordered by Cyperus papyrus and its aquatic macrophytes are in a state of flux. The most significant riparian activity is the large scale production of flowers for the European market. Lake Baringo is approximately 140 km2 and lies in a semi-arid region. Its most noticeable feature is its extreme turbidity which is mainly due to excessive soil erosion resulting from deforestation and overgrazing. This turbidity has led to near extinction of submerged macrophytes and a lake bed virtually devoid of benthic fauna. Fishing pressure has added to the environmental stresses being endured by the fish populations and commercial catches have been detrimentally affected. Accordingly, periods of fishery closure are now imposed upon both lakes. Limited remedial action is feasible and some local stakeholders are attempting to introduce mitigation measures. For Lake Naivasha there is an agreed riparian owners' management plan which tackles issues such as water usage and protection of the C. papyrus margin. For Lake Baringo there is a Rehabilitation of Arid Environments initiative which promotes such activities as restoration of riparian vegetation and appropriate stock management.
Shifts in the food of Nile tilapia, Oreochromis niloticus (L.) in Lake Victoria, Kenya
(African Journal of Ecology, 2004) Muchiri, M.; Cowx, I. G.; Okeyo-Owuor, J. B.; Njiru, M.
Metazoan Parasites of Some Commercially Important Fish along the Kenyan Coast
(WIOMSA, 2004) Aloo-Obudho, Peninah; Anam, R.O.; Mwangi, J.N.
The parasitic fauna of some commercial fish species along the Kenyan coast was investigated at four localities between August 2001 and March 2002. The study was carried out to establish the extent of parasitisation of different fish species and quantify the relationship between the parasites and their fish hosts. Fish samples were collected once a month from four landing beaches. Sixteen fish species were examined out of which only eight were infested with ecto-and endo parasites. The infested fish species included: the rabbitfish (Siganus sutor), the mackerels (Selar crumenophthalmus, Scomberomorus commerson and Rastrelliger kanarguta), parrot fish (Leptoscarus vagiensis), sardine (Sardinella gibbosa), tuna (Thunnus sp.) and needle fish (Hemiramphus far). Of the eight species, Si. sutor was most infested with parasites while Sardinella and Leptoscarus were primarily infested with ectoparasites (isopods). Intensity of infestation increased with age (size), especially in Si. sutor, where very young fish had a low infestation rate, while adults were heavily infested (P < 0.01). No significant differences were observed in the intensity of infestation between sexes in Si. sutor (P > 0.05).
Exotic introductions to the fishery of Lake Victoria: What are the management options?
(2005) Muchiri, M.; Knaap, M. van; Cowx, I. G.; Waithaka, E.; Njiru, M.
Lake Baringo: Addressing threatened biodiversity and livelihoods
(Lakes & Reservoirs: Research & Management, 2006-12) Odada, Eric, O.; Onyando, Japheth, O.; Aloo-Obudho, Peninah
Lake Baringo is a shallow, internal drainage, freshwater lake located in the Kenyan Rift Valley. The lake is an important source of water for humans and livestock, as well as a significant income source for local communities through activities such as tourism, biodiversity conservation, and fish sold in local markets. The lake has been subject to overfishing, as well as to greatly enhanced sedimentation as a result of land use changes in the drainage basin. This paper provides an analysis of the conditions prevailing at Lake Baringo, and examines in detail the management response to the problems facing the lake. The roles of the many and varied institutions in the lake basin's management are discussed, and an analysis of internationally funded projects designed to ameliorate the situation is provided.
Influences of land use/cover on water quality in the upper and middle reaches of River Njoro, Kenya
(Blackwell Publishing Asia Pty Ltd, 2007) Muchiri, Mucai; Shivoga, William A.; Kibichi, Samuel; Odanga, Jethro; Miller, Scott N.; Baldyga, Tracy J.; Enanga, Eric M.; Gichaba, Maina C.
Remote Sensing Applications for Sustainable Aquaculture in Africa
(IEEE, 2007) Quansah, Joseph, E.; Rochon, Gilbert, L.; Quagrainie, Kwamena, K.; Amisah, Steve; Muchiri, Mucai; Ngugi, Charles
The authors review the current state of the science with respect to remote sensing applications for aquaculture, including site location, aquaculture facility mapping, market proximity analysis and associated roadway infrastructure, epizootic mitigation, meteorological event and flood early warning, environmental pollution monitoring, and aquatic ecosystem impact, primarily for catfish (Clarias spp.) and tilapia (Tilapia spp.; Oreochromis spp.), inter alia. The potential of technology transfer from the controlled environment aquaculture research facilities at Purdue University, West Lafayette, Indiana, USA to partnering institutions in Ghana and Kenya are explored. The potential for multi-sensor remote sensing deployment to support sustainable fish production in these environments and subsequently in other African countries is evaluated.
Macroinvertebrate assemblages along a land-use gradient in the upper River Njoro watershed of Lake Nakuru drainage basin, Kenya
(Blackwell Publishing Asia Pty Ltd, 2007) Muchiri, Mucai; Miller, Scott N.; Shivoga, William A.; Kibichii, Samuel
Influences of land use/cover on water quality in the upper and middle reaches of River Njoro, Kenya
(Lakes & Reservoirs: Research and management, 2007-06) Shivoga, William, A.; Muchiri, Mucai; Kibichi, Samuel; Odanga, Jethro; Miller, Scott, N.; Baldyga, Tracy, J.; Enanga, Eric, M.; Gichaba, Maina, C.
Data from 10 sampling sites along the River Njoro are used to examine the contribution of nutrients from upstream land uses draining each of the sampling sites. The data also are used to assess whether both the proportion of land uses and the size of the subwatersheds account for the variability in water quality in the River Njoro watershed. Geographical Information System analysis was used to determine the spatial distribution of land-cover types and subwatersheds contributing run-off to the sampling sites in the River Njoro. Standard Digital Elevation Model-based routines were used to establish the watershed area contributing run-off to each sampling site. Water and sediment samples were collected for chemical analysis, and the nutrient levels were related to the upstream land-use types and the size of the subwatersheds. The mid-stream portion of the River Njoro (near Egerton University) accounts for the highest nutrient contributions. The percentage contribution is magnified by additions from industrial, human settlements and agricultural land uses around the University. There is a significant decrease in nutrient levels downstream, however, indicating natural purification as the river flows through an area of large-scale farming with intense, well-preserved riparian and in-stream vegetation. Steep slopes of the land upstream of Egerton University enhance erosion and nutrient losses from those subwatersheds. Mixed small-scale agricultural and bare lands contribute over 55% of the phosphorus load to the upper and mid-reaches of the River Njoro. The size of the subwatershed accounts for about 53% of the variability in the soluble phosphorus in the river. The land-use subwatershed proportions are important for characterizing and modelling water quality in the River Njoro watershed. Upland land uses are as important as near-stream land uses. We suggest that conservation of intact riparian corridor along the river and its tributaries contributes significantly to natural purification processes and recovery of the ecological integrity of the River Njoro ecosystem.
Changes in population characteristics and diet of Nile tilapia Oreochromis niloticus (L.) from Nyanza Gulf of Lake Victoria, Kenya: what are the management options?
(Taylor &Francis, 2007-11-26) Muchiri, Muchai; Njiru, M.; Okeyo-Owuor, J. B.; Cowx, I. G.; Knaap, M. van der
Economic Gain versus Ecological Damage from the Introduction of Non-native Freshwater Fish: Case Studies from Kenya
(2008) Muchiri, Mucai; Hickley, Phil; Britton, Robert; Boar, Rosalind
Non-native freshwater fish species that have been introduced to the inland waters of Kenya are listed and the consequences of stocking such fish are reviewed. Original species composition and lake ecosystem function can be detrimentally affected but, also, the introduction of non-native species can result in significant economic benefit. In the context of impact on recipient fish communities and the performance of exploited fisheries, the merits or otherwise of alien fish species introductions are discussed with the aid of two case histories; lungfish (Protopterus aethiopicus) in Lake Baringo and a number of species, particularly carp (Cyprinus carpio), in Lake Naivasha.
The risk of pathogenic intestinal parasite infections in Kisii Municipality, Kenya
(BMC Public Health, 2008-07) Nyarango, Robert, M.; Aloo-Obudho, Peninah; Kabiru, Ephantus, W.; Nyanchongi, Benson, O.
Background: Intestinal parasitic infections are among the most common infections worldwide. Various epidemiological studies indicate that the prevalence of intestinal parasites is high especially in developing countries, although in many of these, the environmental risk factors have not been clearly elucidated. The objective of this study was to determine the risk of pathogenic intestinal parasites infections in Kisii Municipality. Methods: Random sampling was used in the selection of the study samples. Stool parasitological profiles of food handlers were done by direct smear and formalin-ethyl acetate sedimentation method. Both vegetable and meat samples were examined for the presence of intestinal parasites. The storage and meat handling practices of the various butcheries were observed. Results: Types of samples examined for occurrence of intestinal parasites includes, a total of 84 vegetable, 440 meat and 168 stool samples. Fifty five (65.5%) vegetable, 334 (75.9%) meat and 69 (41.1%) of the stool samples were found positive for intestinal parasites indicating a high overall risk (66.18%) for intestinal parasite infections. Of the parasites detected, the most common parasites infesting the foodstuffs and infecting the food handlers were Ascaris lumbricoides and Entamoeba histolytica. Parasites were significantly less likely to be present on meat that was refrigerated during display than meat that was displayed at ambient temperature. Conclusion: There is a high risk of infection with intestinal parasites in the sampled Municipal markets. About half of the food handlers surveyed (41.1 %) at the Municipal Hospital had one or more parasitic infections. Furthermore, meat (65.5%) and vegetables (75.9%) sold at the Municipal market were found to be contaminated with parasites hence the inhabitants requires a need for education on food safety, good distribution practices and improvement on sanitary conditions.
Spatial and seasonal variations in phytoplankton community structure in alkaline–saline Lake Nakuru, Kenya
(Blackwell Publishing Asia Pty Ltd, 2009) Mucai, Muchiri; Okoth, Oyoo Elijah; Shivoga, Wiliam A.; Miller, Scott N.; Rasowo, Joseph; Ngugi, Charles Chege
Difficulties of fishing at Lake Naivasha, Kenya: is community participation in management the solution?
(Blackwell Publishing Asia Pty Ltd, 2010) Muchiri, Mucai; Njiru, James Murithi; Ojuok, Jacob E.; Aura, Christopher Mulanda; Kundu, Rodrick
Difficulties of fishing at Lake Naivasha, Kenya: is community participation in management the solution?
(2010) Muchiri, Mucai; Aura, Christopher Mulanda; Kundu, Rodrick; Njiru, James Murithi; Ojuok, Jacob E.
Unlike other lakes in tropical regions, Lake Naivasha exhibits low fish species diversity. The fishery is based on introduced fish species that are not native to the lake. The lake ecosystem is very fragile, as reflected in its fluctuating fish catches. The fishery almost completely collapsed in 2001, due partly to mismanagement and ignorance about needed conservation measures. The Kenyan government, like many governments around the world, recognized the need to involve fishers and other stakeholders, in order to ensure better management of the lake fisheries resources. Also referred to as collaborative management (co-management), this management approach provides the opportunity to share responsibility for managing the fishery resources between the government and the community. A total ban on fishing was imposed in February 2001, lasting for 1 year, to allow lake fish stocks to recover. This study analyses the co-management process for Lake Naivasha, and discusses the role played by the community during the fishing ban, as well as the successes and challenges encountered, and the tribulations and perceptions of the fishers regarding the new management strategy. It also comprises the first documentation of community participation in fisheries management begun for Lake Naivasha in the year 2001.