Spatial and temporal variation in community structure of phytoplankton in chebara reservoir-Kenya

River impoundments create reservoirs for many of varying, sizes which serve one or more functions, and change transform lotic aquatic systems to lentic ones, with changes in physical and chemical properties, biotic assemblage and productivity. Chebara reservoir is located at 36o E and 22o S and situated within Elgeyo-Marakwet County. The reservoir was formed as a result of damming the Moiben River to supply water to Eldoret town. A study was conducted on composition and relative abundance of phytoplankton in the reservoir from December 2007 to April 2008. Sampling was done every month at six stations distributed over the reservoir; one station at inlet of Moiben River, one station at the outlet, three at minor inlets and one within the reservoir. Phytoplankton were collected using a 28nm diameter plankton net immersed vertically below the photic depth. Photic depth was measured using 25cm diameter Secchi disk. Phytoplankton were identified and enumerated using a compound microscope. All statistical analyses were performed with STATIGRAPHIC 2.1 Plus and STATISTICA 6.0 procedures. Six phytoplankton classes were identified which included Cyanophyceae (22 genera) Bacillariophycae (25 genera), Chlorophyceae (55 genera), Euglenophyceae (3 genera), Rhodophyceae (2 genera) Pyraphyceae (6 genera) and Crysophyceae (8 genera) similar to observations made in tropical oligotrophic lakes. The order of abundance was Pyraphyceae> Cyanophyceae> Chlorophyceae> Bacillariophyceae> Crysophyceae>Euglenophyceae>Rhodophyceae. Members of the Class Chlorophyceae showed the highest species diversity and abundance. The results obtained from this study can be used track the effects of catchment land use in the drainage basin investigate the cumulative, long term effects of climate change, and river impoundment on the algal evolution. Key words: Spatial and Temporal Variation, Community Phytoplankton, Chebara Reservoi

Effects of physico-chemical parameters on abundance and biomass of phytoplankton in chebara reservoir-Kenya

River impoundment creates reservoirs of varying sizes that supply water for multiple uses including electric power generation, domestic, agriculture or industry. However, damming of rivers creates an aquatic habitat of slow moving water of varying depths and altogether changing the biotic and physico-chemical status of a waterbody. Chebara reservoir was created to supply water to Eldoret Municipality. Chebara reservoir is located at 36 05 E and 0 22 S and situated within Elgeyo-Marakwet County. A study was conducted on the physico-chemical parameters and the abundance and biomass of phytoplankton in Chebara reservoir from December 2007 to April 2008. Stratified sampling was done every month at six stations distributed over the reservoir; one station at inlet, one station at the outlet, one stationat a minor inlet draining through human settlement, one at minor inletdrainingthrough farmland and one within the reservoir. Temperature, pH and ElectricalConductivity were measured in situusing JENWAY® 3405 Electrochemical Analyser. Secchi depth visibility was measured by vertically immersing a 25cm diameter Secchi disk to disappearance. Phytoplankton were collected using a 28 m diameter plankton net immersed vertically below the photic depth. Phytoplankton was identified and enumerated usingSedgwick—Rafter cell underan invertedor microscope, or Olympus®ModelCK2, atamagnificationofX400. Primary production and biomass were determined by chemical analysis of chlorophyll-a concentration and biological oxygen demand (BOD). Nutrientconcentrations were measured spectrophotometrically, while alkalinity was measuredby acidimetric method. Phytoplankton abundance and biomass were related to the physico-chemical conditions of the reservoir. All statistical analyses were performed with STATIGRAPHIC 2.1 Plus and STATISTICA 6.0 procedures. There were no significant differences in the spatial or temporal physico-chemical parameters. The reservoir was homogenously oligotrophic and alkaline with only very slight variations. among dates and samplingstations. The productivity of Chebara reservoir was low (approximately 0.8 µgmillilitre-1) asestimated by chlorophyll a, suggesting oligotrophy. The highest abundance was observed in March and at station 3,while the lowest abundance in April and at station 5. CCA results indicated strong relationships between the various phytoplankton genera and physical and chemical conditions, except for biological oxygen demand which had a weak effect. The study also indicates that phytoplankton growth in the reservoir is more likely to be limited by availability of P than N. The results obtained from this study can be useful for tracking the effects of changing activities in the drainage basin and the tributaries that contribute water directly to the reservoir. Calcium concentrations were consistently low, but the high abundance of pyraphytes in this reservoir could suggest a need to monitor management practices in the reservoir catchment that maintain calcium concentrations and populations of pyraphytes low in order to reduce the water treatment costs. This research further recommends that a research be carried out on macro invertebrates in order to accumulate sufficient knowledge which will be useful for watershed best management practices aimed at ensuring long term protection for water supply. Keywords: Physico-chemical Parameters; Abundance and Biomass; phytoplankton; Chebara reservoi

Effect of Iron Amino Acid Chelate Supplemented Fish Feeds on Nutrients Composition of Spinach (Spinacia oleracea) in an Aquaponic System in Kenya

Aquaponics is an environmentally friendly production system involving reuse of waste and nutrients in production of fish and vegetables. Currently aquaponic system is the only solution for fish and plants production but one unique challenge is the maintaining of micro and macro-nutrient and the pH balance in the system. The study was conducted at the University of Eldoret for 119 days. A complete randomized design was used. The supplementation rates in fish diets constituted 30g, 20g, 10g and 0g Fe kg-1 respectively. Nile tilapia fry with a mean weight of 0.475 ± 0.025g and nine spinach (height 3 ± 0.131cm, 2 leaves) were stocked in 12 aquaria in an aquaponic system. 30g Fe kg-1 treatment exhibited higher minerals content than other treatments with Phosphorus 67.51 ± 2.42 mgL-1, Zinc 9.06 8± 0.45 mgL-1, Iron 5.2 ± 0.218 mgL-1, Manganese 7.655 ± 0.344 mgL-1, Total Nitrogen 11.248 ± 0.141mgL-1 and Sodium 7.218 ± 0.028 mgL-1. There was improved water quality at 30g Fe kg-1 compared to other treatments. These results revealed that 30g Fe kg-1 iron amino acid chelate supplementation had better nutritional attributes as feedstuff for spinach growth than the three other dietary treatments. The study recommends the incorporation of 30g Fe kg-1 iron amino acid chelate in on-farm formulated diets for aquaponic system where complete diets are not easily accessible for small scale farmers

Distribution of Potentially toxic elements in Water, Sediment and Soils in the Riparian Zones around a Kraft Pulp and Paper Mill in Western Kenya

This chapter discusses the impact of effluent discharge on the distribution of potentially toxic elements (Pb, Cd, Cu and Zn) in water, sediments and soils near a Kraft mill in Western Kenya. Potentially Toxic Elements (PTEs) concentrations were determined at three sites: Water Intake Point, Effluent Discharge Point and Downstream Point. The mill liquid effluent parameters and gaseous emissions were also characterized. One-way ANOVA was used to analyze the spatial differences in PTEs concentrations. Principal component analysis determined the correlations between the proximity to the Kraft mill and the PTEs in soils, water and sediments. In riverine soils, Cd was 0.78 ± 0.01 mg/kg, while Pb was 94.38 ± 9.65 mg/kg. In sediments, the concentration was 16.81 ± 2.46 mg/kg for Zn, 6.16 ± 0.72 mg/kg for Cd and 75.28 ± 5.97 mg/kg for Pb. In water, Zn was 0.26 ± 0.038 mg/L, Cu was 0.75 ± 0.11 mg/L, Cd was 0.05 ± 0.004 mg/L and Pb was 1.26 ± 9.65 mg/L. The spatial distributions of PTEs in soils near the factory and across the river may have resulted from the factory’s effluent discharge and gaseous emissions. These findings should help formulate more stringent industrial effluent management programs in Western Kenya

Effect of stocking density on growth performance of monosex Nile Tilapia (Oreochromis niloticus) in the aquaponic system integrated with lettuce (Lactuca sativa)

Aquaponics is a fish-plant recirculating system where nutrients received from the fish culture are absorbed by the plants for growth. The technology is relatively new for fish culture in Kenya, and the principles and operations remain largely untested for many fish species. This study determined how stocking density affects the growth performance and water quality in a Nile tilapia-lettuce (Lactuca sativa) aquaponics system. The experimental design included five replicates for each of the aquaponic systems stocked at densities of 150, 300, and 450 fish/m3 for a rearing period of 56 days. Each treatment had a planting density of 16 lettuce/m2. The water quality parameters ranges during the rearing period were 3.83–5.35 mg/L for dissolved oxygen, 7.44 to 7.6 for pH, 0.014 mg/L to 0.032 mg/L for total ammonium nitrate (TAN), 1.11–1.34 mg/L for nitrate, and 0.01–0.08 mg/L for nitrite, and all decreased with increasing stocking density. The final weight of fingerlings was 25.2 ± 4.2 g, 32.0 ± 3.8 g and 42.6 ± 3.1 g for 450, 300, and 150 fish/m3 respectively. Specific growth rate (SGR) was reduced with increasing stocking density whereas food conversion ratio (FCR) increased with stocking density. Aquaponic systems with the lowest stocking densities performed better than 300 and 450 fish/m3 respectively

Stock status and some biological aspects of Lethrinus lentjan (Lacapede, 1802) from the south coast of Kenya

The Pinkear Emperor (Lethrinus lentjan, Laćepède, 1802) is among the three demersal species dominating fish catches in the artisanal fishery on the Kenyan coast. Available data indicate that total landings of L. lentjan have declined over the past decade due to possible over-exploitation. This paper provides a brief account of the stock status of this species and biological aspects including length-weight relationship, body condition, and reproduction from a total of 575 fish specimens sampled. Sampling was done at Msambweni, Shimoni, Majoreni and Vanga fish landing sites on the south coast of Kenya from September 2016 to February 2017. Individual total length (TL, cm) and body weight (BW, g) was measured on site while some specimens were dissected for sex and gonad maturity analysis. Mortality, exploitation rate, length-weight relationship, condition factor, fecundity, and size at maturity (L50) were determined. Length frequency analysis indicated that L. lentjan was exploited above the optimum level, at E = 0.55 (exploitation rate). Growth was allometric with the length exponent (b = 2.95) being significantly <3. Mean fecundity was 89,573 ± 9,841 eggs/female/year. Gonadosomatic index was highest in January (2.08 ± 0.20) suggesting a possible peak spawning period at this time. The study provides a brief scientific overview of L. lentjan as a baseline for future in-depth biological studies of this species along the Kenyan coast.

Effect of Black Soldier Fly (Hermetia illucens) Larvae Feed Supplement on Length-Weight Relationship of Nile Tilapia (Oreochromis niloticus)

One of the main challenges in the aquaculture sector is the high cost of fishmeal, which accounts for about 70 percent of production costs. The black soldier fly (BSF) larvae meal could be an alternative because of its high protein and essential fatty acids contents that are important for fish to grow and develop normally.An analysis was carried out to examine the effect of various feeding strategies on the growth and performance of Nile tilapia (Oreochromis niloticus). Five diets with equal nitrogen content were enriched with BSF larvae meal at different proportions (0%, 25%, 50%, 75%, and 100%). The meal with 0% BSF was used as a control. The length and weight of the fish were collected biweekly, while mortality data were collected daily. The study assessed the length and weight relationship of the fish using the parameter 'b'(regression coefficient). From this research, 'b' was found to range from 3.230 to 3.635, indicating isometric growth patterns. The well-being of the experimental fish was also evaluated through the condition factor 'K,' which ranged from 0.907 to 1.002, suggesting that all the fish were in good health. We, therefore, conclude that substituting the conventional fish means with black soldier fly larvae appears to be possible and impacts fish growth normally

Effect of Black Soldier Fly (Hermetia illucens) Larvae Feed Supplement on Length-Weight Relationship of Nile Tilapia (Oreochromis niloticus)

One of the main challenges in the aquaculture sector is the high cost of fishmeal, which accounts for about 70 percent of production costs. The black soldier fly (BSF) larvae meal could be an alternative because of its high protein and essential fatty acids contents that are important for fish to grow and develop normally.An analysis was carried out to examine the effect of various feeding strategies on the growth and performance of Nile tilapia (Oreochromis niloticus). Five diets with equal nitrogen content were enriched with BSF larvae meal at different proportions (0%, 25%, 50%, 75%, and 100%). The meal with 0% BSF was used as a control. The length and weight of the fish were collected biweekly, while mortality data were collected daily. The study assessed the length and weight relationship of the fish using the parameter 'b'(regression coefficient). From this research, 'b' was found to range from 3.230 to 3.635, indicating isometric growth patterns. The well-being of the experimental fish was also evaluated through the condition factor 'K,' which ranged from 0.907 to 1.002, suggesting that all the fish were in good health. We, therefore, conclude that substituting the conventional fish means with black soldier fly larvae appears to be possible and impacts fish growth normally

Characterization of the nutritional quality of amaranth leaf protein concentrates and suitability of fish meal replacement in Nile tilapia feeds

A number of leafy vegetables, their protein concentrates and hydrolasates are under evaluation as alternative protein ingredients to fish meal (FM) in aquafeeds. This study evaluated the nutritional characteristics and suitability of replacing FM with the amaranth (Amaranthus hybridus) leaf protein concentrates (ALPC) as a protein ingredient in the diet of Nile tilapia (Oreochromis niloticus). Experimental diets were formulated, where 100%, 75%, 50%, 40%, 20% and 0% FM protein was substituted by protein from ALPC. The six dietary treatments were tested in triplicate in static flow-through tanks. The substitution effects were compared in terms of fish growth performance, nutrient utilization, whole body composition and apparent nutrient digestibility. After 160 days of feeding, the growth, nutrient utilization and Feed Conversion Ratio (FCR) in fish fed diets containing 100%, 75%, 50%, 40% and 20% FM were better (P < 0.05) than those fed diet with 0% FM. The Apparent nutrient digestibility was high for protein, lipid and energy and differed significantly among the dietary treatments (P < 0.05). Protein digestibility in fish was highest in feed formulated with 100%, 75%, 50% and 40% FM, which were significantly (P < 0.05) higher than at 25% and 0% FM. Lipid digestibility was comparable for all the diets except fish fed 0% FM. Digestible carbohydrates and dry matter were similar for all dietary treatments (P < 0.05). We demonstrate that it is possible to replace up to 80% of fish meal with ALPC without compromising the performance O. niloticus. These results demonstrate that although it is possible to replace large part of fish meal with ALPC, it is not possible to eliminate it in Nile tilapia diet as alternative protein ingredient

Ojunga(Etiegni)_Impact of a Kraft Pulp and Paper Mill Effl uent on

Phytoplankton and macroinvertebrate assemblages were used to assess the impact of a kraft pulp and paper mill effluent in Kenya, on River Nzoia downstream of the discharge point in relation to changes in water quality during May to June and November 2008 (rainy and dry seasons, respectively). Total phosphorus concentration increased from 0.027 mg·L-1 upstream to 0.04 mg·L-1 downstream. Ammonia nitrogen (NH3-N) concentration was 0.51 mg·L-1 upstream and 0.86 mg·L- 1 downstream. Nitrate concentration stood at 1.18 mg·L-1 upstream compared with the 2.23 mg·L-1 downstream. The pH changed from 4.5 to 5.0 upstream to 5.5 to 6.0 downstream, while DO increased from 6.57 to 7.03 mg·L-1 downstream. The BOD5 (biochemical oxygen demand after five days) values remained almost unchanged from 4.63 mg·L-1 upstream to 4.67 mg·L-1 downstream. Taxon composition of phytoplankton and macroinvertebrates correlated with adverse environmental gradients resulting from the mill’s effluent discharge. Overall, there was a shift in composition and abundance of both phytoplankton and macroinvertebrates, with the downstream site recording high numbers of tolerant taxa (i.e., Microcystis sp. and Chironomus sp.). It was recommended that water quality monitoring with effluents of this nature be done using a combination of chemical analysis and biological indicators such as phytoplankton and macroinvertebrate