Phytoplankton flora and its dynamics in the Eastern Harbour of Alexandria

ABSTRACT

Phytoplankton communities of the Eastern Harbour were collected monthly from August 1986 to July 1987. Seventy seven species were recorded, belonging to Bacillariophyceae [48], Dinophyceae [13], Chlorophyceae [7], Cyanophyceae [6], Euglenophyceae [2] and one Chrysophyceae. Although numerous species were encountered, yet very few of them formed the main bulk of the community Chaetoceros affinis, Cyclotella meneghiniana, Amphicrysis compressa and Alexandrium minutum. The mean phytoplankton crop varied from 0.2x10[6] to 19x10[6] cells L[-1] in surface water and was lower in bottom layer. In the last few years the quantitative cycle of the standing crop density did not follow the previously observed seasonal trend. This is the result of increasing eutrophication which also causes a decrease in cell dimensions for most recorded species