PHYTOPLANKTON COMMUNITY IN ABU-QIR BAY AS A HOT SPOT ON THE SOUTHEASTERN MEDITERRANEAN COAST.

PHYTOPLANKTON COMMUNITY IN ABU-QIR BAY AS A HOT
SPOT ON THE SOUTHEASTERN MEDITERRANEAN COAST.
N.G. SHAMS-EL-DIN* AND M.M.DORGHAM**
* National Institute of Oceanography and Fisheries, Alexandria, Egypt.
** Oceanography Department, Faculty of Science, Alexandria University.
ABSTRACT
The phytoplankton community in the stressed part of Abu Qir Bay was studied monthly
relative to the prevailing ecological conditions from April 1998 to March 1999 at eight
stations. The study recorded a total of 182 species of both fresh and marine origins,
belonging to diatoms (89 species), chlorophytes (34 species), dinoflagellates (26 species),
cyanophytes (18 species), euglenophytes (12 species), silicoflagellates (2 species), and
cryptophyte (one species). Most of the recorded species occurred either seasonally or
rarely, while small number of them appeared as persistent. The diversity of the
phytoplankton community experienced wide variations on both monthly and spatial scales,
accompanied by analogous variations in the diversity index, richness and evenness. The
phytoplankton count was low (0.01 x 103
– 12.5 x 103
unit/L) all the year round, except high
density in September (55.6 x 103
units/L). In contrast, chlorophyll-a attained markedly high
values over the year (2.06 – 52.64 g/L). The diatoms Nitzschia pungens and Asterionella
japonica were the predominant, in addition to Chaetoceros affinis, Thalassionema
nitzschioïdes and the dinoflagellate Prorocentrum micans. The phytoplankton count
showed insignificant correlation with the nutrient salts, may be due to the water
deterioration, resulting from the acute eutrophication and the increase of pollution stress in
the bay. The present study revealed a marked drop in phytoplankton abundance as
compared to the earlier records.