Potential impact of some abiotic parameters on a phytoplankton community in a confined bay of the Eastern Mediterranean Sea: Eastern Harbour of Alexandria, Egypt

Abstract

The Eastern Harbour (E.H.) is sheltered from the sea by a breakwater with two main entrances through which exchange with the netitic Mediterranean water takes place. Some physico-chemical parameters of the study area showed that dissolved oxygen ranged from 6.57 to 11.4 mg l-1 at the open sea station and 5.08 to 11.71 mg l-1 for the E.H. stations. Higher nutrient concentrations were recorded in the E.H. than that at the open sea station, except for ammonia and nitrate. The phytoplankton flora of the E. H. stations was much richer in species than the adjacent open sea station, attaining 96 and 74 species, respectively. As well as the average phytoplankton density, it was higher in the surface water than near the bottom water layer. With regard to the total phytoplankton community, Bacillariophyceae dominated at all sites, whereas Dinophyceae, Chlorophyceae, Cyanophyceae and Euglenophyceae were rarely recorded. The highest average density of phytoplankton abundance was recorded during March, both at the surface. Correlation coefficient of biological factors with some physico-chemical parameters and a series of stepwise multiple regression equations describing the dependence of phytoplankton density on the changes of most abiotic prevailing conditions are provided and discussed.