Seasonal variations of phytoplankton and related nutrients in Sawa Lake, Iraq.
Al-Saadi, Hussain*,1, Hassan, Fikrat*,2, Alkam, Foad*,3, 1 Department of Biology, Baghdad, Iraq2 Department of Biology, Hilla, Iraq3 Department of Biology, Dewania, Iraq
ABSTRACT- Subsurface water samples for qualitative and quantitative study of phytoplankton and associated nutrients, were taken monthly from three selected stations in Sawa Lake, southern Iraq, for 18 months starting in October 1999 through to March 2001. Nitrate was the dominant inorganic from of nitrogen and has a significant negative correlation with chlorophyll-a concentration and the total number of algal cells. Similar correlation was found between phosphate values. N:P ratio ranged between 11:1 to 12.6:1. Silicate values were greater than 16 g/L. A bimodal distribution was found in chlorophyll a concentration and total cell number of phytoplankton with two annual peaks, one in spring and another in autumn. Diatoms dominated in species and in total cell numbers, followed by blue greens in species numbers, and green algae in total cell numbers. Three species were the most dominant in total cell number (less than 5%) during the study period in all stations, namely Chlorella vulgaris, Scenedesmus bijuga, and Cyclotella meneghiniana. There were no pronounced differences in all of the parameters measured among the three stations.
Key words: marshes, Mesopotamia, Iraq, algae
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