Phytoplankton Composition at Jeddah Coast–Red Sea, Saudi Arabia in Relation to some Ecological Factors

Phytoplankton succession in relation to some physicochemical characters of some water bodies at jeddah coast (saudi arabia) was studied for one year (2004). the sampling program included four different areas, north obhour, technology area, down town area and south jeddah area. water samples were analyzed for some physico-chemical parameters (temperature, ph, s‰, dissolved oxygen (do), calcium (ca^+2) & magnesium (mg^+2), nitrite (no2), nitrate (no3), ammonia (nh3), reactive orthophosphate (po4) and reactive silicate (sio3) as well as phycological parameters (phytoplankton communities and chlorophyll a). the jeddah coast was found to be oligotrophic ecosystem in some areas, while some of these areas were mesotrophic with high phytoplankton density such as the down town and south jeddah areas. the results showed that, the high phytoplankton density attaining the maximum of 2623.2 x 10^3/m^3 at down town area during spring and the minimum of 118.7 x 10^3/m^3 at technology area during winter. seventy three species belonging to 73 genera and 5 groups were recorded. dinophyceae was the first dominant group forming 43.8% of the total phytoplankton communities followed by bacillariophyceae 27.9%. ceratium sp, amphora ovalis, pleurosigma salinatum, trichodesmium sp and synochoccus sp were tolerant species and considered as eutrophic indicators.