SHORT-TERM SCALE OBSERVATIONS ON PHYTOPLANKTON IN THE EASTERN HARBOR OF ALEXANDRIA, EGYPT

SHORT-TERM SCALE OBSERVATIONS ON PHYTOPLANKTON
IN THE EASTERN HARBOR OF ALEXANDRIA, EGYPT
FEDEKAR MADKOUR*, MOHAMED DORGHAM** AND MAMDOUH FAHMY
FAHMY***
* Department of Marine Sciences, Faculty of Science, Suez Canal University.
** Oceanography Department, Faculty of Science, Alexandria University.
*** National Institute of Oceanography and Fisheries, Alexandria.
[email protected]
Keywords: Phytoplankton – Eastern Harbor – Nutrient salts – Weekly observations
ABSTRACT
The species composition and abundance of phytoplankton beside surface salinity and
nutrient salts (ammonia, nitrate, phosphate and silicate) were studied weekly from 24
December 2002 to 9 December 2003 at a fixed station in the Eastern Harbor of Alexandria.
The results indicated that, surface salinity showed relatively wide variations, while nutrient
salts displayed wide and rapid changes on the short term scale. Ammonia fluctuated within
the range of 0.15 – 43.7 µM/L, nitrate: 0.42 – 72.8 µM/L, phosphate: 0.12 to 3.4 µM/L, and
silicate: 0.8 – 12.1 µM/L. Parallel to the above mentioned conditions, the phytoplankton
count varied between a minimum of 0.12×103
unit/L and a maximum of 1.21×106
unit/L,
while chlorophyll a fluctuated from 0.3 to 17.58 µg/L. Both the count and biomass
(Chlorophyll a) displayed several peaks over the year The phytoplankton community was
represented by a total of 151 species, including 76 diatom species, 61 dinoflagellates, and a
few representatives of different freshwater groups. Eighteen species appeared as dominant,
but most of them dominated once a year and the rest dominated intermittently 2-3 times,
except the dinoflagellate Alexandrium minutum which dominated five times over the year.
As compared to the earlier records, the present study reported serious changes in both the
water fertility and the dynamics of the phytoplankton community in the Eastern Harbor.