PHYTOPLANKTON STANDING CROP AND SPECIES DIVERSTIY IN RELATION TO SOME WATER CHARACTERISTICS OF SUEZ BAY (RED SEA), EGYPT.

Abstract

Phytoplankton standing crop and species composition in Suez Bay were studied and discussed in relation to the environmental physico-chemical parameters during 2002-2003. A total of 80 species and varieties were recorded and identified at the selected stations of the bay'/Of them 47 species and 29 genera of diatoms; 19 species and 11 genera of dinoflagellat es; seven species of cyanophytes within four genera; six species of chlorophytes among four genera and one species of chrysophytes. Two main phytoplankton peaks were recorded during spring and autumn seasons (average of 15,676 and 15,376 unit.!/1 respectively). The diatom species responsible of these peaks were, Nitzschia pungens var. atlantica, Asierionellajapomca, Skeletonema costatum, Chaetoceros decipiens and Gyrosigma attenuatitm. The species diversity showed a minimum value at the sewage treating company (ABB station) ranging from 2.17-3.36 nats. While, the highest diversity values were recorded at the unpolluted station, Aiyoon Mousa (VI) and varied from 2.74-3.61 nats. The results revealed regional and seasonal inverse correlation between diversity and phytoplankton standing crop in Suez Bay and it is regarded as a pollution habitat. The results of N:P ratio indicated that Suez Bay is generally P-limited, mainly due to the high load of nitrogenous compounds specially ammonia, which formed about 60.7:1 % of the total inorganic nitrogen, followed by nitrate (33.7 %) and:nitrite (5.57 %). Dissolved inorganic phosphate recorded with annual average of 0.98 pmoIX1. Generally, the level of nutrient salts indicated that Suez Bay is in the eutrophic state.