Browsing by Author "Wondie, Abebaw"

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    Temporal Dynamics of Phytoplankton Biomass and Primary Production in Relation To Some Physico-Chemical Variables in Lake Hora-Arsedi, Ethiopia.
    (Addis Ababa University, 2006-06) Wondie, Abebaw; Kifle, Demeke(PhD)
    Diatoms and green algae became more important during periods of Precipitation (August-September, 2005 and March-April, 2006). The Phytoplankton biomass varied from 19.1 to 47.6 (mean =33.42) and from 21.5 to 53.15 (mean = 37.47) mg m-3 at the central and near-shore stations respectively. The vertical distribution of photosynthetic activity was of a typical pattern for phytoplankton with light-inhibition at the surface on all sampling dates. Light-saturated rate of photosynthesis (Amax) ranged from _ 473 to 1230 mg O2 (_ 147.6 to 383.8 mg C) m-3 h-1) at the central station. Lack of correspondence between phytoplankton biomass and Amax was apparent. Biomass-specific rate of photosynthetic production at lightsaturation, photosynthetic capacity (Pmax) ranged from 13.6 to 52.8 mg O2 (mg Chl a)-1 h-1 at the central station. An inverse relationship between photosynthetic capacity (Pmax) and phytoplankton biomass (B) was also observed. The hourly integral photosynthetic rate (_A) ranged 0.41 to 2.0 g O2 (_ 0.128 to 0.62 g C) m-2 h-1 and the R2 value shows that biomass explains 0.4% of the variance in _A. The daily integral photosynthetic rates ((__A ) estimated ranged from 3.0 to 18.0 g O2 (_ 0.94 to 5.62 g C ) m-2 d- 1.The temporal variations in the taxonomic composition, biomass and primary production of phytoplankton are discussed in relation to some physico-chemical and biological variables.