Browsing by Author "Kaaya, Lulu Tunu"

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    Phytoplankton diversity and productivity wiht emphasis on the bloom dymamics of the potentially toxic cynobacterrium arthrospira fusiformis in Momela lake,Arusha, Tanzania
    (University of Dar es Salaam, 2007) Kaaya, Lulu Tunu
    Limnological studies were conducted in Momela lakes ( Small Moinela, Big momela and Tulusia)for analysis of phyloplankton species composition, abudance, and biomass ( chlorophyll ‘’a’’) and environmental parameters (TSS, alkalinity, Ph salinity). transparency, water temperature and hardness and inorganic nutrients) as well estimamtions of primary production and nitrogen fixation rates, sampling was conducted once per month for a period of one year ( May 2005 to April 2006) .Calculated Shannon-weaver diversity indicates were higher in lake Small momela compared to lake big momela and Tulusia. Arthaspira fusiformis was the most dominant species in lake big (up to 1840 filaments/m1) while it existed at background concentrations in Lake Small Momela (maximum of 9 filaments/m1). Phytoplankton biomass was significantly and consistently low in Lake Small Momela compared to Lake Big Momela and Tulusia. However, there were no significant seasonal variations in phytoplankton biomass and abundance of a fusiformis. Environmental parameters were fairly stable showing insignificant temporal variations during the study period. However significant spatial variations in salinity and alkalinity among the hikes were noted. Lake Small Momela had significantly less, salinity and alkalinity levels compared to Lake Big Momela and Tulusia. Also, there were no significant differences in the rates of gross- and net-primary productivity as well as nitrogen fixation among the lakes and between seasons. In general, limnological parameters in Momela lakes did not vary much between seasons but much variation were observed among the lakes.