Aquaponics
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Publication Application of AquaCrop model in deficit irrigation management of cabbages in Keiyo Highlands(2013-07-31) Kiptum C, K.; Kipkorir E, C.; Munyao T, M.; Ndambuki, J. M.Crop growth can be simulated under different water application using simulation models. The main purpose of deficit irrigation is high water productivity with less application of water to plants. In this research, the potential of AquaCrop to simulate the growth of cabbages in Keiyo Highlands (0°22’45’’N and 35°32’9”, 2586 m.a.s.l) under nine different irrigation treatments in the dry season between December to February was studied. Statistical comparisons of observed and simulated biomass showed that R2 = 0.96, Root mean square error (RMSE) = 0.38 tons and coefficient of residuals = -0.17. The results showed that the model overestimated the biomass of cabbages. The model also provided excellent simulation of canopy and yield. In this study water productivity of 17 g/cm2 and Harvest index of 76% were found for cabbages. Key words: Deficit irrigation, AquaCrop, cabbage ‘Riana’ and water productivity.Publication Assessment of Ecological Vulnerability to Climate Variability on Coastal Fishing Communities: A Study of Ungwana Bay and Lower Tana Estuary, Kenya(Elsevier, 2018-09-01) Dzoga, Mumini; Simatele, Danny; Munga, CosmasFisheries resources are important in supporting the livelihood of many coastal communities especially in the developing tropical countries. Fisheries resources however, continue to face unprecedented pressure from the impacts of climate change, and this presents both ecological and socio-economic challenges to the dependent communities. This paper assessed the ecological vulnerability to climate variability of artisanal fishing communities in Ungwana Bay and the Lower Tana Delta in Kenya, using selected fin fish species. A combination of approaches were adopted and used to identify and determine exposure, sensitivity, and adaptation indicators. These included a critical review of existing literature, socio-economic survey, and computation of temperature and rainfall variation using long term data from 1983 to 2015. The method of Equal Weights (EW) was applied to all indicators after normalization. The data was normalized in a scale of 0–1, where 0 indicated low vulnerability level and 1 high vulnerability. By using composite index, the selected Ngomeni and Ozi fishing communities within the larger Ungwana Bay and Lower Tana Delta indicated high levels of vulnerability of 0.9 and 0.8 respectively. Due to high vulnerability level and poor adaptation capacity by the local fishing communities in the selected study sites, we recommend government and non-governmental agencies to reinforce community based organizations (CBOs) activities on ecological conservation and social network creation to promote short and long term adaptation measures.Publication Assessment of Ecological Vulnerability to Climate Variability on Coastal Fishing Communities: A Study of Ungwana Bay and Lower Tana Estuary, Kenya(Elsevier, 2018-09-01) Dzoga, Mumini; Simatele, Danny; Munga, CosmasFisheries resources are important in supporting the livelihood of many coastal communities especially in the developing tropical countries. Fisheries resources however, continue to face unprecedented pressure from the impacts of climate change, and this presents both ecological and socio-economic challenges to the dependent communities. This paper assessed the ecological vulnerability to climate variability of artisanal fishing communities in Ungwana Bay and the Lower Tana Delta in Kenya, using selected fin fish species. A combination of approaches were adopted and used to identify and determine exposure, sensitivity, and adaptation indicators. These included a critical review of existing literature, socio-economic survey, and computation of temperature and rainfall variation using long term data from 1983 to 2015. The method of Equal Weights (EW) was applied to all indicators after normalization. The data was normalized in a scale of 0–1, where 0 indicated low vulnerability level and 1 high vulnerability. By using composite index, the selected Ngomeni and Ozi fishing communities within the larger Ungwana Bay and Lower Tana Delta indicated high levels of vulnerability of 0.9 and 0.8 respectively. Due to high vulnerability level and poor adaptation capacity by the local fishing communities in the selected study sites, we recommend government and non-governmental agencies to reinforce community based organizations (CBOs) activities on ecological conservation and social network creation to promote short and long term adaptation measures.Publication Assessment of the Value of the Small Scale Fish Farming Enterprises in Nyamira County, South West Kenya(International Journal of Innovative Research and Advanced Studies (IJIRAS), 2019-09) Lagat, Caroline J.; Kibet, Noah; Omasaki, Simion; Getabu, AlbertFish farming is relatively recent compared to subsistence crop farming in Nyamira County. It is becoming significant due to its contribution to nutrition, self employment and income generation. A Cost Benefit Analysis was conducted from March-October 2016, to estimate its viability. Semi structured questionnaire was used to collect data from 320 farmers using simple random sampling technique. Focused group discussion schedules were administered to three groups of ten farmers to collect extra data. Further information was collected on data returns of harvests from farmers and from interview schedules of fifteen key informants. Data were analysed using Statistical Package for the Social Science (SPSS) version 20.0 and Excel spreadsheet programme. Chi square (χ 2 ) was used to test if there were significant differences between profits obtained by farmers at p=0.05. Results indicated that the mean input cost per farmer ranged from Ksh 46.08±0.08-Ksh 50.34±58m-2 . A positive correlation between total feed costs and net income (R) ranged from 0.479-0.519. Cost Benefit Ratio indicated that Borabu had the highest (4.66) followed by Manga (1.51) and by Nyamira North (1.31). A similar trend was observed on Rate of Returns on Investment with Borabu having 3.64, Nyamira North 0.44 and Manga 0.75. New farmers obtained low net income due to costs incurred on construction of new ponds. Most commonly used feeds were vegetables, kitchen remains and Rastrineobola argentea. This study demonstrates that small scale aquaculture can be profitable when appropriate inputs are provided.Publication Characterisation of Artisanal Catches in Selected Fishing Areas of The Lower Tana Delta and Malindi-Ungwana Bay, Kenya(Western Indian Ocean Journal of Marine Science, 2020-10-29) Dzoga Mumini; Simatele Danny; Munga CosmasShore-based assessment of fisheries resources in Ngomeni, Kipini and Ozi fishing areas of Malindi-Ungwana Bay and the Lower Tana Delta on the north coast of Kenya was conducted from January to December 2017 to establish catch composition, species richness, and fishing effort (catch-rate, number and types of fishing gears and crafts) in the marine, estuarine and riverine habitats. Distinct catch composition (R = 0.27, P < 0.05) was observed across the three habitats. Catch composition differed significantly spatially and seasonally across the three fishing areas, and between the north east (NE) and south east (SE) monsoon seasons (R = 0.332, P < 0.05). The wolf herring, Chirocentrus dorab, was the most abundant fish species in Ngomeni, centrally located in Malindi-Ungwana Bay, while the catfishes, Arius africanus and Clarias gariepinus, were the most abundant species in Kipini and Ozi, respectively. Gillnets operated from dhows (mashua) and fibre-reinforced plastic (FRP) boats in Ngomeni (marine), and canoes using-basket traps in Ozi (riverine), landed significantly larger Spanish mackerel, Scomberomorus commerson, and sea catfish, Arius africanus (Kruskal Wallis test: Df = 2; F = 197.141; p < 0.001; Df = 2, F = 490, p < 0.001), respectively. Species diversity by area in combination with habitat and type of fishing craft showed higher diversity for Ngomeni in the marine habitat with mashua fishing crafts than in Kipini. Significantly different catch rates (Df = 2, F = 10.43, p<0.001; Df = 1, F = 5.897, p < 0.021) were observed in the three (3) fishing areas and during the NE monsoon and the SE monsoon, respectively. Canoes were the most common fishing craft used, especially in Ngomeni, accounting for 37.1%, and 97.5% in Ozi, while mashua crafts accounted for 44.5% of the total fishing craft in Kipini. Monofilament nets were most common in Ngomeni (34.0%) while basket traps dominated the Ozi site at 63.6%. The Kipini area was dominated by handlines (28.8%). It is therefore evident that the three (3) fishing areas of the Malindi-Ungwana Bay and Lower Tana Delta showed significant differences in catch composition and size of fish caught, attributed partly to the variation in habitat types and fishing methods between the sites. Overall, the Ngomeni area was characterized by more advanced fishing craft with the majority powered by engines, including mashua and FRP boats, compared to Kipini and Ozi fishing areas where canoes were dominant.Publication Optimization of biogas production from anaerobic co-digestion of fish waste and water hyacinth(BioMed Central (BMC), 2023-07-06) Ingabire, Hortence; M’arimi, Milton M.; Kiriamiti, Kirimi H.; Ntambara, BonifaceMany fresh water bodies face a great challenge of an invasive weed called water hyacinth (WH) which has great impacts on the environment, ecology, and society. Food and Agriculture Organization (FAO) estimates that over nine million tons of Fish wastes (FW) are thrown away each year. The fish waste generated poses environmental and health hazards because in most cases it is either disposed into pits or discarded onto the open grounds. Both WH and FW are potential substrates for biogas production. However, utilization of FW substrate alone has a limitation of producing a lot of amounts of volatile fatty acids (VFAs) and ammonia. Their accumulation in the digester inhibits substrate digestion. Consequently, as stand-alone it is not suitable for anaerobic digestion (AD). This can be overcome by co-digestion with a substrate like WH which has high carbon to nitrogen (C/N) ratio prior to biodigestion. Experimental variable levels for biogas were substrate ratio (WH:FW, 25–75 g), inoculum concentration (IC, 5–15 g/250 mL), and dilution (85–95 mL). Design-Expert 13 was used for optimization and results analysis. Response surface methodology (RSM) was used to examine the effects of operating parameters and identify optimum values for biogas yield. Optimum values for maximum biogas with the highest methane yield of 68% were found to be WH:FW ratio, 25:75 g, 15 g of IC, and 95 mL for dilution. The yield was 16% and 32% greater than FW and WH mono-digestion, respectively. The biogas yield was expressed as a function of operating variables using a quadratic equation. The model was significant (P < 0.05). All factors had significant linear and quadratic effects on biogas while only the interaction effects of the two factors were significant. The coefficient of determination (R2) of 99.9% confirmed the good fit of the model with experimental variables.Publication Small-Scale Fisheries of the Tana Estuary in Kenya(Western Indian Ocean Journal of Marine Science, 2021-12-23) Manyenze, Fatma; Munga, Cosmas N.; Mwatete, Chrisestom; Mwamlavya, Hamadi; Groeneveld, Johan C.The role of small-scale fisheries in maintaining socio-ecological systems (SES) in the Western Indian Ocean is well-documented, yet few studies have addressed estuarine fisheries in the region. Small-scale fisheries in the Tana Estuary in Kenya are described in this paper, accounting for location along a salinity gradient, seasonality, gear types used, species composition and relative abundance of landings. Monthly shore-based sampling was undertaken at four locations in 2017 – Ungwana Bay near the estuary mouth, lower and mid-estuary, and upper estuary at Ozi village, ⁓10 km upstream. Fishing gear comprised of seine nets, gillnets, hook-and-line and traditional gear such as self-made traps, sticks and spears operated from the shore (foot fishers), dugout canoes, dhows and fibreglass boats with outboard engines. A total of 12,840 fish and crustacean specimens belonging to 89 species in 45 families were sampled. Landings were dominated by catfishes Arius africanus (31 %) and Clarias gariepinus (21 %), small pelagic fishes Pellona ditchela (10 %) and several sardine species (⁓5 %), croaker Otolithes ruber (10 %), eel catfish Plotosus limbatus (6 %), mullet Mugil cephalus (4 %) and Nile tilapia Oreochromis niloticus (4 %). Multivariate analyses (nMDS and ANOSIM) found that fishing gear (p < 0.05) and location (p = 0.001) significantly influenced catch composition, but season (p = 0.146) was not significant. Traps were used in the upper and mid estuary only and were selective for three catfish species. Seine nets (54 species) and gillnets (40 species) were least selective and used at all four locations. Rarefaction curves indicated that species diversity was higher at the bay and lower estuary than the mid and upper estuary, and that diversity was highest for canoe-gillnet and canoe-encircling net combinations. Catch rates (avg. of 2.3 to 8.4 kg.fisher-1.day-1) depended on gear type and was highest for monofilament gillnets. Catches comprised a broad size range of multiple species, but on average, seine nets selected smaller individuals than traps, gillnets and long lines. The high complexity and organization of the fishery at an estuary-scale makes it a good example of a relatively intact SES suitable for regional comparative analyses.Publication The Biology of Goldsilk Sea Bream (Family: Sparidae) from the Inshore Waters of North Coast Kenya(Western Indian Ocean Journal of Marine Science, 2019-11-21) Anam, Rashid O.; Munga, Cosmas N.; Gonda, James R.The biology of the sparid, Acanthopagrus berda (goldsilk sea bream) was investigated using catch samples obtained from artisanal fishers at selected fish landing sites in the Marereni and Ngomeni fishing areas on the north coast of Kenya. This species has not previously been studied in Kenya although it forms significant proportions of artisanal fish landings and is also a promising aquaculture species. In order to contribute to knowledge of this species, the length-weight relationship, condition factor and feeding preference for prey items were studied in a total of 751 specimens sampled from July 2013 to July 2014. Length-weight relationships for male and female individuals from both fishing areas were strongly correlated (Males: Marereni - R2 = 0.920, Ngomeni - R2 = 0.983; Females: Marereni - R2 = 0.966, Ngomeni - R2 = 0.941). The condition factor of mixed sexes was not significantly different between the two fishing areas (Marereni 2.15 ± 0.08; Ngomeni 2.05 ± 0.02) at p > 0.05. Gut content analysis recorded a total of 5 taxa in the diet (gastropods, molluscs, detritus, crustaceans and fish). The overall sample was dominated by female individuals with an overall sex ratio of females (405 individuals) to males (338 individuals) of 1:0.8 being significantly different at p < 0.05. The species exhibited isometric and positive allometric growth patterns, indicative of the physiological well-being of this species on the north coast of Kenya. Gonadal maturation occurred throughout the year with peaks in July, August and September. However, more work is needed on the biology, distribution, spawning grounds, behavior, and migration patterns along the Kenyan coast.Publication Utilisation of Amaranth and Finger Millet as Ingredients in Wheat Dough and Bread for Increased Agro-Food Biodiversity(Foods, 2022-03) Onyango Calvin; Luvitaa S. K; Lagat Kibet; Hüsken Alexandra; Smit Inga; Schmidt MarcusAbstract Amaranth and finger millet are important food security crops in Africa but show poor bread making ability, even in composite wheat breads. Malting and steaming are promising approaches to improve composite bread quality, which have not been fully explored yet. Therefore, in this study, wheat was blended with native, steamed or malted finger millet or amaranth in the ratio of 70:30. Wheat/native amaranth (WHE-NAM) and wheat/malted amaranth (WHE-MAM) had longer dough development times and higher dough stabilities, water absorption capacities and farinograph quality numbers than wheat/steamed amaranth (WHE-SAM), wheat/native finger millet (WHE-NFM), wheat/steamed finger millet (WHE-SFM) or wheat/malted finger millet (WHE-MFM). The WHE-NAM and WHE-MAM breads had lower crumb firmness and chewiness, higher resilience and cohesiveness and lighter colours than WHE-NFM, WHE-SFM and WHE-MFM. Starch and protein digestibility of composite breads were not different (p > 0.05) from each other and ranged between 95–98% and 83–91%, respectively. Composite breads had higher ash (1.9–2.5 g/100 g), dietary fibre (5.7–7.1 g/100 g), phenolic acid (60–122 mg/100 g) and phytate contents (551–669 mg/100 g) than wheat bread (ash 1.6 g/100 g; dietary fibre 4.5 g/100 g; phenolic acids 59 mg/100 g; phytate 170 mg/100 g). The WHE-NAM and WHE-MAM breads possessed the best crumb texture and nutritional profile among the composite breads.