Browsing by Author "Ayuk, James"

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    The effects of detergent and fertilizer toxicity on growth rate, nutrient utilization and survival of Clarias gariepinus (Burchell) fingerlings reared under controlled condition
    (International Journal of Fisheries and Aquatic Studies, 2020) Hammed, Ayofe, M; Amosu, Albert, O; Ayuk, James
    Study on the effects of metals on growth rate and survival of Clarias gariepinus (Burchell 1822) fingerlings bred in tanks containing water concentrated with inorganic fertilizer and detergent was conducted. 300 fingerlings of C. gariepinus (7.5±0.24) were stocked into different tanks of 5000m3 capacity water and fed with formulated diet for 8 weeks. The tanks were treated with 0ml, 50ml, 100ml, 150ml, 200ml and 250 ml of inorganic detergent and fertilizer respectively. The metal content in the fish was determined through wet acid digestion and extraction procedure using Atomic Absorption Spectrophotometer, while growth was determined using indices method. The values obtained for Cu, Zn, Mg, P, Cd, Pb, Mn, K and Na respectively were generally below the Federal Environmental Protection Agency (FEPA) limits. The survival rate recorded for fingerlings treated with fertilizer was 99% for all concentrations but a range between 88% to 0% survival was recorded for fingerlings stocked in detergent treated water. Toxicity behavior response observed in this study were, slow movement, gulping for atmospheric oxygen, darting and erratic swimming. The results obtained indicated that concentration of 50ml detergent and 100ml of fertilizer were the suitable and tolerable limits in terms of growth and survival for culturing C. gariepinus fingerlings.
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    Water regime requirements and possible climate change effects on Fynbos Biome Restionaceae
    (University of the Western Cape, 2018) Ayuk, James; Raitt, Lincoln
    The Cape Floristic Region (CFR) of southern Africa is one of the world’s most unique biodiversity hotspots. However, this biodiversity continues to be threatened by habitat loss due to rapid urbanisation, agriculture and alien vegetation encroachment, and now, by future groundwater extraction and climate change. Previous work had shown that soil moisture is important in structuring wetland plant communities at fine-scale. What is not fully known, however, is how the spatial distribution of species at a local scale is related to soil hydrology and what the response in the future of species distributions will be to perturbations arising from changes in climate or subsurface moisture in the future. The current research investigated the water regime of the Restionaceae which is a key family in the Fynbos biome and the implications of possible changes in soil hydrology caused by climate change in communities within this region. The Restionaceae were particularly appropriate because they are shallow rooted perennials with the ability to tolerate a wide range of water regimes which allows them to successfully co-habit within mixed plant communities as segregated clusters along fine-scale hydrologic gradients. Vegetation survey counts for the presence of these species along with measurements of soil water table depth and moisture content data generated from eight small-scale plots (50 x 50 m) were used to investigate the possible hydrological niches and to envision the potential impacts of a substantial reduction in rainfall and an increase in temperature as projected by Global Climate Models (GCMs) on the structure of Restionaceae communities in seasonal wetlands by 2100. A comparative analysis of the effects of two extreme Representative Concentration emission Pathways (RCP2.6 and RCP8.5) on significant hydrological variables to plant water regimes was carried out. The IPCC AR5 report describes the RCP8.5 emissions scenario as the likely ‘business as usual’ scenario where emissions continue to rise through the 21st century while the RCP2.6 scenario assumes that emissions peak between 2010 and 2020 and substantially subside thereafter.