Both Little and Great Bitter lakes are the central and most important water body (85% of the canal system) of the Suez Canal. The Great Bitter Lake lies at 30º 14´ 30º 25´ latitudes and 32º 17´ - 32º 30´ longitudes with a total length of 24 km, maximum width of 13 km. total surface area of 312 km2, undredged depth of 6 m and maximum dredged depth of 23 m. Moreover, Great Bitter Lake has a unique marine water ecosystem with uniform water temperature, salinity being above the sea level and its water movements are probably due to tidal influence from the Suez Gulf.
The distribution and species composition of microplankton community in the Great Bitter Lake area were carried out during the period November 1991 - November 1992. Fifly-nine microplankton species belonging to four floristic groups of diatoms, dinoflagellates. green and blue green algae as well as two faunistic groups of tintinnids and foraminiferids
were catalogued. Diatoms constituted about 66.79% of the total plankton number, followed by dinofiagellates (17.27%). tintinnids (6.7%), green algae (6.4%), for aminiferids (2.18%) and finally blue green algae with 0.66% of the total counts. Site and seasonal dynamics of phytoplankton as well as protozooplankton and their herbivorous activity provide the major route for the herbivorous fate of phytoplankton in the Great Bitter Lake at the southern part of the Suez Canal.