Seasonal variations and community structure of plankton in relation to some environmental variables in Wadi Haneefah Stream, Riyadh, Saudi Arabia

Abstract

En
A study on the qualitative and quantitative variations of phytoplankton and zooplankton populations as well as physico-chemical condition of water at three different locations in Wadi Haneefah Stream was carried out. Water temperature fluctuated between 18.0°C and 32.0°C, while pH values ranged from 7.1 to 8.5. Dissolved oxygen concentration reached maximum in May. The contents of chloride, Alkalinity and sulphate were highest in July-August. It is found that most of the parameters studied (turbidity, conductivity, hardness, total nitrogen, total dissolved solids, phosphorus, BOD and COD) have high values in summer months (June – September). A total of 50 phytoplanktonic taxa representing the families Chlorophyceae, Cyanophyceae, Desmidiaceae and Bacillariophyceae were recorded during the present study. Among all, Bacillariophyceae was the dominating group. The population density of phytoplankton was more prominent in summer. Zooplankton community was represented mainly by Protista, Rotifera, and Crustacea. These zooplankton was peaked in July and trough in January. The effects of various physico-chemical quality parameters on the seasonal distribution and succession of planktonic organisms are also discussed.