Transformation towards sustainable and resilient WASH services: Proceedings of the 41st WEDC International Conference, 2018
This study estimates the efficiency of Kangemi Sewage Plant. Hence, contributing to understanding... more This study estimates the efficiency of Kangemi Sewage Plant. Hence, contributing to understanding the performance of the treatment plant and its impacts on water pollution. The plant treats wastewater through conventional processes. For environmental quality assurance, its performance requires a consistent monitoring to evaluate the impact of the effluents to the receiving waters. Changes in the properties of the effluent can occur along the treatment process, but the final effluent quality is determined by the effectiveness of the treatment process. Key nutrients (Nitrogen and Phosphorus), TSS and BOD5 were determined as the water quality indicators. Kruskal-Wallis test was run at p<0.05 significance. Nitrogen, BOD5 and TSS indicated a significant difference among the sites. No significant difference for Phosphorus and pH. Removal efficiency for (BOD5), TSS, Ammonia and TN were 60%, 85%, 59% and 54% respectively. Consequently, the plant had a high removal efficiency for N but low for P. Background information Increase in human population, urbanization and enhanced surface runoff from agricultural lands has accelerated generation of wastewater into the recipient waterbodies. Municipal waste and sewage are disposed indiscriminately into water systems such as streams and rivers, posing a threat to pollution of surface water in developing countries (Solomon, 2009). Discharge of wastes due to anthropogenic activities into aquatic systems has resulted to their degradation by frequent reception of domestic and industrial wastes, therefore exposing humans and aquatic biota to multiple health hazards (Bakare et al., 2003). Consequently, this has led to pollution of these systems with excessive nutrients, organic wastes, dissolved ions and inorganic compounds. Kithiia (2012) pointed out that surface water systems in Kenya are increasingly being polluted from both point and diffuse sources as a result of rapid industrialization, urbanization, intensive farming coupled to poor planning for waste management, leading to discharge of wastes into aquatic ecosystems. Increased nutrient concentrations and suspended matter are some of the major properties of degraded river water quality particularly due to sewage input. In a sewage plant, nutrients, organic matter and other contaminants removal varies depending on level of contaminants in the influents and the methods used in the treatment, which will in turn determine the efficiency of their removal. For example, according to USEPA, (2000), removal of nitrogen depends on organic loading which affects efficiency of nitrification in the wastewater. Ineffective control of surface water pollution through poor wastewater treatment compromises water quality, increases treatment costs of drinking water and is a potential health and environmental hazard. Hosetti and Frost, (1998) have suggested that regular monitoring of chemical and biological constituents should be implemented to facilitate regulatory standards to be met before discharge of effluents. Discharging untreated or inadequately treated wastewater into surface waters, including rivers, can facilitate eutrophication due to increased nutrient levels. Materials and methods The study site, Kangemi Treatment Plant, lies on (0°25'S and 36°58'E) and discharges effluent into Chania River, in Nyeri County, Central Kenya. Nyeri Town has a population of 119, 273 and an area of 183.10 Km2
Fertilisers and pesticides are increasingly used in agriculture to improve productivity and prote... more Fertilisers and pesticides are increasingly used in agriculture to improve productivity and protect crops from fungi and insects. However, these farm inputs may lead to adverse effects on aquatic biodiversity through eutrophication and pesticide toxicity. This study aimed to establish the effects of nutrient-only, pesticide-only, combined nutrients and pesticides, and control on the abundance of Daphnia magna, and algal biomass. In each of the treatments, different concentrations of nutrients and pesticides residues were added separately or in combination. Responses were measured every 24 hrs, and the experiments ended after 168 hrs of exposure. The experiment was set in four concentration treatments comprising high, moderately high, moderately low, and low concentrations. Data analysis was done using Multiple Analysis of Variance (MANOVA)and ANOVA to determine the effect of time, concentrations and the interaction of time and concentrations for each of the treatments on D. magna abundance, and algal biomass. Higher concentrations of pesticide additives were associated with lower abundance of D. magna, and higher algal biomass over the exposure periods. There was a signi cant reduction in the abundance of D. magna in the combined treatment indicating the toxic effect of pesticide addition. Determination of effect concentrations based on combined nutrients-pesticides experiments becomes important in setting water quality standards, and monitoring the quality status, to avoid underestimating the ecological implications of combined contamination.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
We present the findings of a participatory experiment on integrated aquaculture-agriculture syste... more We present the findings of a participatory experiment on integrated aquaculture-agriculture systems (Fingerponds) at the Lake Victoria wetlands, Kenya. Fingerponds are flood-based lacustrine or floodplain wetland fishponds. The aim of the study was to explore, within a wetland/floodplain interface environment, the potential of semi-intensive fish production to enhance the wetland fishery and protect the natural ecosystem from wide-scale, destructive encroachment. The ponds were stocked naturally by flood water. After flood recession, livestock manure was added to the ponds and the effects of manuring on water and sediment quality and fish yields were studied. Manuring had positive effects on the nitrogen, phosphorous and chlorophyll a concentrations of the pond water. Regression analysis results indicated that site, manuring and environmental and climatic variables explained 58-70% of the variation in dissolved nitrogen and phosphorous, and 71% of the variation in chorophyll a. Manuring enhanced the total phosphorus concentration in the sediment but it only had marginal effects on total nitrogen. Although the net fish yields were highly variable between sites and seasons, ranging from 402 to 1069 kg ha-1 , the data showed that manuring was advantageous. The duration of the culture period, site variability and manuring explained 82% of the variation in fish yields. We conclude that Fingerponds fertilized with livestock manure from abutting riparian subsistence agriculture can improve fish production, enhance food diversity and security and contribute to more efficient use of papyrus wetlands for food production. This in turn may reduce large-scale conversion of wetlands to agriculture.
Water is considered a basic commodity and essential for life living on planet earth is dependent ... more Water is considered a basic commodity and essential for life living on planet earth is dependent on it. However, access to water has been and will continue to be a dilemma for a majority of the residents at the coast of Kenya. A close look at the window on “Coastal Resources and People” reveals that water is a key resource but despite its immense importance, many people especially in the rural areas and among the Vulnerable and Marginalized Groups (VMG’s) do not have adequate access to potable, reliable and convenient sources of water. Lamu, currently considered among water scarce counties in Kenya as per the Lamu County Integrated Development Plan (http://lamu.go.ke/wp-content/uploads/2016/03/LAMU_CIDP-Revised.June_2014-1.pdf), faces serious challenge of provision of potable water to its residents. With the influx of people from other parts of the country as a result of the implementation of the Kenya Vision 2030 flagship project Lamu Port Southern Sudan Ethiopia Transport (LAPSSET...
Energie wird von Wasserdienstleistern (Water Services Providers; WSPs) für die Entnahme, Aufberei... more Energie wird von Wasserdienstleistern (Water Services Providers; WSPs) für die Entnahme, Aufbereitung und Verteilung von Trinkwasser benötigt, am meisten (ca. 90%) wird für Pumpen und Pumpsysteme verwendet. Die Energiekosten könnten zwischen 30-50% der laufenden Kosten von WSPs liegen. Der Energieverbrauch ist jedoch der größte kontrollierbare Eingangsparameter innerhalb der Versorgungsgrenzen mit kurzen Amortisationszeiten bei Investitionen. Enorme Energiekosten für die Wasserversorgung, die hauptsächlich auf Pumpenineffizienzen, Spitzentarife und mit Wasserverlusten verbundener Energie zurückzuführen sind, beeinträchtigen die Fähigkeit der WSPs, den aktuellen und wachsenden Wasserbedarf zu decken. Im Zusammenhang mit WSPs in Afrika wurden bis zu 70% nicht einnahmenbezogene Wasserverluste in Wasserversorgungssystemen gemeldet. Dies führt zu einem äquivalenten Energieeintrag, der mit solchen Wasserverlusten verbunden ist. Dies trägt folglich zu einer schlechten Betriebsleistung der ...
The use of both fertilizers and pesticides in the Lake Naivasha Catchment, is associated with agr... more The use of both fertilizers and pesticides in the Lake Naivasha Catchment, is associated with agricultural intensification and has resulted in enrichment of aquatic ecosystems with nutrients, coupled with exposure of aquatic biota to pesticide residues affecting aquatic ecosystem structure and function. This study explored the changes in land use and related it with the concentrations of nutrients and selected pesticides, to show the potential of combined (nutrients and pesticides) risks associated with agricultural intensification in Lake Naivasha catchment, a tropical catchment in Kenya. The results indicate that between 1989 and 2019 there was an increase of cropland by 623 km2, a reduction of forest cover by 200 km2, increase of grasslands by 534 km2, a reduction in bare soils by 100 km2, and an increase of 540 km2 of built area. The land cover changes were correlated with increased concentrations of nutrients and pesticides in surface waters across sampling sites monitored in 2...
The aim of this study was to investigate the use of attached algae also known as periphyton as in... more The aim of this study was to investigate the use of attached algae also known as periphyton as indicators of inorganic pollution in Nyangores tributary of Mara River in Kenya. The river suffers impacts of agricultural pollutants in its upper course due to the intensive farming activities in this region coupled with other anthropogenic activities which result into the production of various pollutants that finally find their way into this river The river was sampled twice a month from February 2012 to May 2012, at eight in which the data on nutrients and periphyton community structure and biomass were collected. Simultaneously, physical and chemical variables such as water temperature, conductivity, discharge, total suspended solids, pH, dissolved oxygen, ammonium, nitrate, nitrite, soluble reactive phosphorus, total phosphorus were measured. In order to interpret the influence of the environmental on the periphyton characteristics, two-way ANOVA was used. The data collected was stati...
International Journal of Fisheries and Aquatic Studies, 2020
Length and weight data for three species of fish Oreochromis niloticus, Lates niloticus, and Sydo... more Length and weight data for three species of fish Oreochromis niloticus, Lates niloticus, and Sydontus victorianus was collected from three East African lakes, Lake Victoria, Lake Baringo and Lake Naivasha. Correlation were done on weight and length based on the fish species, the lake collected from, sex, and the age. Correlation was found not to be a good measure of evaluating length weight relationship. Models had to be applied. Linear models, random regression models, proportional hazard models and threshold models. Random regression model was found to capture most of the information though it excluded the age of the fish on mean sum of squares error. The challenge with this is that it's a long-term model which accounts for hatching to last date of the fish life.
The trophic state of Lake Baringo and factors that could be limiting the development of algal bio... more The trophic state of Lake Baringo and factors that could be limiting the development of algal biomass in it were investigated during one wet/dry hydrological cycle in 2014-2015. Water samples were analysed for dissolved inorganic nutrients, including NH + 4 , NO 2 − and NO 3 − , total phosphorus and Chlorophyll a. Light attenuation was estimated using Secchi depth. The trophic state was determined using Carlson trophic state indices (CTSI). Deviations in CTSI, nutrient ratios and ambient nutrient concentrations were used to identify factors limiting phytoplankton growth. The mean values measured for Secchi depth, nitrate, total phosphorus and Chlorophyll a showed significant seasonal variation (p < 0.05). Based on the Carlson trophic state index, the results show that Lake Baringo is eutrophic. However, the lake is also experiencing phosphorus limitation and poor light penetration, because of high turbidity, which is more pronounced during the wet season.
Rice is an important food crop in Kenya and is the third most consumed cereal crop after maize an... more Rice is an important food crop in Kenya and is the third most consumed cereal crop after maize and wheat. The high demand for rice has resulted in the conversion of wetlands to rice paddies and the increased use of fertilizer, ultimately reducing the ability of wetlands to store carbon. Consequently, emissions from wetlands of three potent greenhouse gases (GHGs): methane (CH 4), nitrous oxide (N 2 O), and carbon dioxide (CO 2) have increased. This study assessed the influence of fertilizer application on GHGs emission, organic carbon and nutrient stocks in rice paddies in papyrus dominated wetlands in the Nzoia River basin in Kenya. Sampling was done on a weekly basis for the first two months, and thereafter twice per month in the Anyiko rice paddies, which is a smallholder system partly converted from the Anyiko wetland. Two replicates of three fertilization treatments (standard, control and under fertilization) were assigned randomly in six rice plots. The static chamber method was used to collect the GHGs, which were then analyzed using gas chromatography. Soil samples were collected and analyzed for nitrogen and organic carbon stocks. Statistical tests revealed no significant differences in organic carbon and nitrogen stocks among the three fertilization treatments. The mean CH 4 fluxes did not differ significantly among the three treatments where mean flux for control plots were 8.30 ± 4.79 mgm −2 h −1 ; under-fertilized plots had a mean of 6.93 ± 2.42 mgm −2 h −1 and standard fertilized plots mean fluxes were 4.00 ± 6.34 mgm −2 h −1. Similarly, CO 2 mean fluxes were insignificantly different among the three treatments, where control plots had mean of 174.80 ± 26.81 mgm −2 h −1 , under-fertilized plots mean were 208.81 ± 36.20 mgm −2 h −1 and standard fertilized plots mean fluxes were 248.29 ± 41.22 mgm −2 h −1. However, mean N 2 O fluxes were significantly different among the three treatments, control plots had a mean of −3.59 ± 2.56 µgm −2 h −1 , followed by underfertilized with mean of −0.59 ± 0.45 µgm −2 h −1 and standard fertilized plots with mean of 4.37 ± 3.18 µgm −2 h −1. In this study, different fertilization scenarios had significant effects on N 2 O emission but no significant effect on CO 2 and CH 4 emission, organic carbon and nutrient stocks. Therefore, there is need for sustainable use of wetlands to ensure a balanced role between ecosystem management and human services.
This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluc... more This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluctuations for Lake Baringo over the past 200 years as a consequence of climatic variations. A 285 cm long sediment core sample was collected using a Rod-Operated Single-drive Stationary Piston corer. Lake level was inferred using indices based on the proportion of planktonic to benthic diatom taxa (P/B ratio). The sediment archive presented distinct zones dominated by planktonic and benthic diatom flora. An initial transgression in the early 19th century was characterised as a shallow water environment dominated by planktonic Aulacoseira spp. This was a response to extreme drought during the late 18th to early 19th century. Mid-19th century was defined by a high lake stand. The late 19th to early 20th centuries experienced low water level following the widely documented aridity at the time. The mid-20th century was marked by a spectacular rise in water level that coincided with remarkably wet years during the early 1960s and late 1970s. The first decade of the 21st century witnessed widespread changes in water level. The proxy records show that lake ramping and drawdown over the years follow approximately 50-year climatic cycles.
Fish samples (541) were collected every two weeks from different parts of Lake Naivasha using gil... more Fish samples (541) were collected every two weeks from different parts of Lake Naivasha using gill nets (50 mm to 150 mm mesh size) and beach seines (< 10 mm) between November 2013 and February 2014.The main focus of the study was on sex ratio, length-weight relationship and body condition of Nile tilapia. Results revealed that there were more males sampled with a sex ratio of male to female of 2:1. A comparison of the length-weight relationship for males and females showed that most of the fish had negative allometric growth (b <3) with males from Oserian and Hippo sampling stations point showing isometric growth (b =3). Length at first fish maturity of male and female fish obtained during this study was 17.7 cm TL and 18.0 cm TL respectively. The results from this study showed that fish in the lake are in good condition with condition factor value above 1.
Transformation towards sustainable and resilient WASH services: Proceedings of the 41st WEDC International Conference, 2018
This study estimates the efficiency of Kangemi Sewage Plant. Hence, contributing to understanding... more This study estimates the efficiency of Kangemi Sewage Plant. Hence, contributing to understanding the performance of the treatment plant and its impacts on water pollution. The plant treats wastewater through conventional processes. For environmental quality assurance, its performance requires a consistent monitoring to evaluate the impact of the effluents to the receiving waters. Changes in the properties of the effluent can occur along the treatment process, but the final effluent quality is determined by the effectiveness of the treatment process. Key nutrients (Nitrogen and Phosphorus), TSS and BOD5 were determined as the water quality indicators. Kruskal-Wallis test was run at p<0.05 significance. Nitrogen, BOD5 and TSS indicated a significant difference among the sites. No significant difference for Phosphorus and pH. Removal efficiency for (BOD5), TSS, Ammonia and TN were 60%, 85%, 59% and 54% respectively. Consequently, the plant had a high removal efficiency for N but low for P. Background information Increase in human population, urbanization and enhanced surface runoff from agricultural lands has accelerated generation of wastewater into the recipient waterbodies. Municipal waste and sewage are disposed indiscriminately into water systems such as streams and rivers, posing a threat to pollution of surface water in developing countries (Solomon, 2009). Discharge of wastes due to anthropogenic activities into aquatic systems has resulted to their degradation by frequent reception of domestic and industrial wastes, therefore exposing humans and aquatic biota to multiple health hazards (Bakare et al., 2003). Consequently, this has led to pollution of these systems with excessive nutrients, organic wastes, dissolved ions and inorganic compounds. Kithiia (2012) pointed out that surface water systems in Kenya are increasingly being polluted from both point and diffuse sources as a result of rapid industrialization, urbanization, intensive farming coupled to poor planning for waste management, leading to discharge of wastes into aquatic ecosystems. Increased nutrient concentrations and suspended matter are some of the major properties of degraded river water quality particularly due to sewage input. In a sewage plant, nutrients, organic matter and other contaminants removal varies depending on level of contaminants in the influents and the methods used in the treatment, which will in turn determine the efficiency of their removal. For example, according to USEPA, (2000), removal of nitrogen depends on organic loading which affects efficiency of nitrification in the wastewater. Ineffective control of surface water pollution through poor wastewater treatment compromises water quality, increases treatment costs of drinking water and is a potential health and environmental hazard. Hosetti and Frost, (1998) have suggested that regular monitoring of chemical and biological constituents should be implemented to facilitate regulatory standards to be met before discharge of effluents. Discharging untreated or inadequately treated wastewater into surface waters, including rivers, can facilitate eutrophication due to increased nutrient levels. Materials and methods The study site, Kangemi Treatment Plant, lies on (0°25'S and 36°58'E) and discharges effluent into Chania River, in Nyeri County, Central Kenya. Nyeri Town has a population of 119, 273 and an area of 183.10 Km2
Fertilisers and pesticides are increasingly used in agriculture to improve productivity and prote... more Fertilisers and pesticides are increasingly used in agriculture to improve productivity and protect crops from fungi and insects. However, these farm inputs may lead to adverse effects on aquatic biodiversity through eutrophication and pesticide toxicity. This study aimed to establish the effects of nutrient-only, pesticide-only, combined nutrients and pesticides, and control on the abundance of Daphnia magna, and algal biomass. In each of the treatments, different concentrations of nutrients and pesticides residues were added separately or in combination. Responses were measured every 24 hrs, and the experiments ended after 168 hrs of exposure. The experiment was set in four concentration treatments comprising high, moderately high, moderately low, and low concentrations. Data analysis was done using Multiple Analysis of Variance (MANOVA)and ANOVA to determine the effect of time, concentrations and the interaction of time and concentrations for each of the treatments on D. magna abundance, and algal biomass. Higher concentrations of pesticide additives were associated with lower abundance of D. magna, and higher algal biomass over the exposure periods. There was a signi cant reduction in the abundance of D. magna in the combined treatment indicating the toxic effect of pesticide addition. Determination of effect concentrations based on combined nutrients-pesticides experiments becomes important in setting water quality standards, and monitoring the quality status, to avoid underestimating the ecological implications of combined contamination.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
We present the findings of a participatory experiment on integrated aquaculture-agriculture syste... more We present the findings of a participatory experiment on integrated aquaculture-agriculture systems (Fingerponds) at the Lake Victoria wetlands, Kenya. Fingerponds are flood-based lacustrine or floodplain wetland fishponds. The aim of the study was to explore, within a wetland/floodplain interface environment, the potential of semi-intensive fish production to enhance the wetland fishery and protect the natural ecosystem from wide-scale, destructive encroachment. The ponds were stocked naturally by flood water. After flood recession, livestock manure was added to the ponds and the effects of manuring on water and sediment quality and fish yields were studied. Manuring had positive effects on the nitrogen, phosphorous and chlorophyll a concentrations of the pond water. Regression analysis results indicated that site, manuring and environmental and climatic variables explained 58-70% of the variation in dissolved nitrogen and phosphorous, and 71% of the variation in chorophyll a. Manuring enhanced the total phosphorus concentration in the sediment but it only had marginal effects on total nitrogen. Although the net fish yields were highly variable between sites and seasons, ranging from 402 to 1069 kg ha-1 , the data showed that manuring was advantageous. The duration of the culture period, site variability and manuring explained 82% of the variation in fish yields. We conclude that Fingerponds fertilized with livestock manure from abutting riparian subsistence agriculture can improve fish production, enhance food diversity and security and contribute to more efficient use of papyrus wetlands for food production. This in turn may reduce large-scale conversion of wetlands to agriculture.
Water is considered a basic commodity and essential for life living on planet earth is dependent ... more Water is considered a basic commodity and essential for life living on planet earth is dependent on it. However, access to water has been and will continue to be a dilemma for a majority of the residents at the coast of Kenya. A close look at the window on “Coastal Resources and People” reveals that water is a key resource but despite its immense importance, many people especially in the rural areas and among the Vulnerable and Marginalized Groups (VMG’s) do not have adequate access to potable, reliable and convenient sources of water. Lamu, currently considered among water scarce counties in Kenya as per the Lamu County Integrated Development Plan (http://lamu.go.ke/wp-content/uploads/2016/03/LAMU_CIDP-Revised.June_2014-1.pdf), faces serious challenge of provision of potable water to its residents. With the influx of people from other parts of the country as a result of the implementation of the Kenya Vision 2030 flagship project Lamu Port Southern Sudan Ethiopia Transport (LAPSSET...
Energie wird von Wasserdienstleistern (Water Services Providers; WSPs) für die Entnahme, Aufberei... more Energie wird von Wasserdienstleistern (Water Services Providers; WSPs) für die Entnahme, Aufbereitung und Verteilung von Trinkwasser benötigt, am meisten (ca. 90%) wird für Pumpen und Pumpsysteme verwendet. Die Energiekosten könnten zwischen 30-50% der laufenden Kosten von WSPs liegen. Der Energieverbrauch ist jedoch der größte kontrollierbare Eingangsparameter innerhalb der Versorgungsgrenzen mit kurzen Amortisationszeiten bei Investitionen. Enorme Energiekosten für die Wasserversorgung, die hauptsächlich auf Pumpenineffizienzen, Spitzentarife und mit Wasserverlusten verbundener Energie zurückzuführen sind, beeinträchtigen die Fähigkeit der WSPs, den aktuellen und wachsenden Wasserbedarf zu decken. Im Zusammenhang mit WSPs in Afrika wurden bis zu 70% nicht einnahmenbezogene Wasserverluste in Wasserversorgungssystemen gemeldet. Dies führt zu einem äquivalenten Energieeintrag, der mit solchen Wasserverlusten verbunden ist. Dies trägt folglich zu einer schlechten Betriebsleistung der ...
The use of both fertilizers and pesticides in the Lake Naivasha Catchment, is associated with agr... more The use of both fertilizers and pesticides in the Lake Naivasha Catchment, is associated with agricultural intensification and has resulted in enrichment of aquatic ecosystems with nutrients, coupled with exposure of aquatic biota to pesticide residues affecting aquatic ecosystem structure and function. This study explored the changes in land use and related it with the concentrations of nutrients and selected pesticides, to show the potential of combined (nutrients and pesticides) risks associated with agricultural intensification in Lake Naivasha catchment, a tropical catchment in Kenya. The results indicate that between 1989 and 2019 there was an increase of cropland by 623 km2, a reduction of forest cover by 200 km2, increase of grasslands by 534 km2, a reduction in bare soils by 100 km2, and an increase of 540 km2 of built area. The land cover changes were correlated with increased concentrations of nutrients and pesticides in surface waters across sampling sites monitored in 2...
The aim of this study was to investigate the use of attached algae also known as periphyton as in... more The aim of this study was to investigate the use of attached algae also known as periphyton as indicators of inorganic pollution in Nyangores tributary of Mara River in Kenya. The river suffers impacts of agricultural pollutants in its upper course due to the intensive farming activities in this region coupled with other anthropogenic activities which result into the production of various pollutants that finally find their way into this river The river was sampled twice a month from February 2012 to May 2012, at eight in which the data on nutrients and periphyton community structure and biomass were collected. Simultaneously, physical and chemical variables such as water temperature, conductivity, discharge, total suspended solids, pH, dissolved oxygen, ammonium, nitrate, nitrite, soluble reactive phosphorus, total phosphorus were measured. In order to interpret the influence of the environmental on the periphyton characteristics, two-way ANOVA was used. The data collected was stati...
International Journal of Fisheries and Aquatic Studies, 2020
Length and weight data for three species of fish Oreochromis niloticus, Lates niloticus, and Sydo... more Length and weight data for three species of fish Oreochromis niloticus, Lates niloticus, and Sydontus victorianus was collected from three East African lakes, Lake Victoria, Lake Baringo and Lake Naivasha. Correlation were done on weight and length based on the fish species, the lake collected from, sex, and the age. Correlation was found not to be a good measure of evaluating length weight relationship. Models had to be applied. Linear models, random regression models, proportional hazard models and threshold models. Random regression model was found to capture most of the information though it excluded the age of the fish on mean sum of squares error. The challenge with this is that it's a long-term model which accounts for hatching to last date of the fish life.
The trophic state of Lake Baringo and factors that could be limiting the development of algal bio... more The trophic state of Lake Baringo and factors that could be limiting the development of algal biomass in it were investigated during one wet/dry hydrological cycle in 2014-2015. Water samples were analysed for dissolved inorganic nutrients, including NH + 4 , NO 2 − and NO 3 − , total phosphorus and Chlorophyll a. Light attenuation was estimated using Secchi depth. The trophic state was determined using Carlson trophic state indices (CTSI). Deviations in CTSI, nutrient ratios and ambient nutrient concentrations were used to identify factors limiting phytoplankton growth. The mean values measured for Secchi depth, nitrate, total phosphorus and Chlorophyll a showed significant seasonal variation (p < 0.05). Based on the Carlson trophic state index, the results show that Lake Baringo is eutrophic. However, the lake is also experiencing phosphorus limitation and poor light penetration, because of high turbidity, which is more pronounced during the wet season.
Rice is an important food crop in Kenya and is the third most consumed cereal crop after maize an... more Rice is an important food crop in Kenya and is the third most consumed cereal crop after maize and wheat. The high demand for rice has resulted in the conversion of wetlands to rice paddies and the increased use of fertilizer, ultimately reducing the ability of wetlands to store carbon. Consequently, emissions from wetlands of three potent greenhouse gases (GHGs): methane (CH 4), nitrous oxide (N 2 O), and carbon dioxide (CO 2) have increased. This study assessed the influence of fertilizer application on GHGs emission, organic carbon and nutrient stocks in rice paddies in papyrus dominated wetlands in the Nzoia River basin in Kenya. Sampling was done on a weekly basis for the first two months, and thereafter twice per month in the Anyiko rice paddies, which is a smallholder system partly converted from the Anyiko wetland. Two replicates of three fertilization treatments (standard, control and under fertilization) were assigned randomly in six rice plots. The static chamber method was used to collect the GHGs, which were then analyzed using gas chromatography. Soil samples were collected and analyzed for nitrogen and organic carbon stocks. Statistical tests revealed no significant differences in organic carbon and nitrogen stocks among the three fertilization treatments. The mean CH 4 fluxes did not differ significantly among the three treatments where mean flux for control plots were 8.30 ± 4.79 mgm −2 h −1 ; under-fertilized plots had a mean of 6.93 ± 2.42 mgm −2 h −1 and standard fertilized plots mean fluxes were 4.00 ± 6.34 mgm −2 h −1. Similarly, CO 2 mean fluxes were insignificantly different among the three treatments, where control plots had mean of 174.80 ± 26.81 mgm −2 h −1 , under-fertilized plots mean were 208.81 ± 36.20 mgm −2 h −1 and standard fertilized plots mean fluxes were 248.29 ± 41.22 mgm −2 h −1. However, mean N 2 O fluxes were significantly different among the three treatments, control plots had a mean of −3.59 ± 2.56 µgm −2 h −1 , followed by underfertilized with mean of −0.59 ± 0.45 µgm −2 h −1 and standard fertilized plots with mean of 4.37 ± 3.18 µgm −2 h −1. In this study, different fertilization scenarios had significant effects on N 2 O emission but no significant effect on CO 2 and CH 4 emission, organic carbon and nutrient stocks. Therefore, there is need for sustainable use of wetlands to ensure a balanced role between ecosystem management and human services.
This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluc... more This article presents a fossil diatom-based, semi-quantitative reconstruction of water level fluctuations for Lake Baringo over the past 200 years as a consequence of climatic variations. A 285 cm long sediment core sample was collected using a Rod-Operated Single-drive Stationary Piston corer. Lake level was inferred using indices based on the proportion of planktonic to benthic diatom taxa (P/B ratio). The sediment archive presented distinct zones dominated by planktonic and benthic diatom flora. An initial transgression in the early 19th century was characterised as a shallow water environment dominated by planktonic Aulacoseira spp. This was a response to extreme drought during the late 18th to early 19th century. Mid-19th century was defined by a high lake stand. The late 19th to early 20th centuries experienced low water level following the widely documented aridity at the time. The mid-20th century was marked by a spectacular rise in water level that coincided with remarkably wet years during the early 1960s and late 1970s. The first decade of the 21st century witnessed widespread changes in water level. The proxy records show that lake ramping and drawdown over the years follow approximately 50-year climatic cycles.
Fish samples (541) were collected every two weeks from different parts of Lake Naivasha using gil... more Fish samples (541) were collected every two weeks from different parts of Lake Naivasha using gill nets (50 mm to 150 mm mesh size) and beach seines (< 10 mm) between November 2013 and February 2014.The main focus of the study was on sex ratio, length-weight relationship and body condition of Nile tilapia. Results revealed that there were more males sampled with a sex ratio of male to female of 2:1. A comparison of the length-weight relationship for males and females showed that most of the fish had negative allometric growth (b <3) with males from Oserian and Hippo sampling stations point showing isometric growth (b =3). Length at first fish maturity of male and female fish obtained during this study was 17.7 cm TL and 18.0 cm TL respectively. The results from this study showed that fish in the lake are in good condition with condition factor value above 1.
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