Physicochemical parameters and zooplankton composition in addition to abundance were studied weekly for a year at a fixed station in the Eastern Harbor (EH), a semi-closed basin in Alexandria. The recorded values of physicochemical parameters included temperature (16.4-31.4 ^oC); salinity (32.3-35.9 ‰), dissolved oxygen (3.5-9.3 mg/l), and water pH (7.43–8.76). The following nutrient salts were determined: nitrate (0.3-32.1 µM), nitrite (0.35-7.34 µM), ammonium (0.95 -5 µM), silicate (7.01-56.3 µM) and total phosphorus (5.76 -73.9 µM). The annual average of zooplankton was 49405 ind. /m³. The number of zooplankton species was 65 recorded in the eastern harbor, with the dominance of Protozoa (32 species), followed by Copepoda (17 species). Phosphorus concentration as an environmental variable showed a positive correlation with the Copepoda and Ostracoda and the dominant group. Cladocera performed a significant positive relationship with ammonia. Cluster analysis illustrated three zooplankton community alignments with each other. Interestingly, the information and observation of this research would be very useful in formulating policies and regulatory frameworks for sustainable management of the Eastern Harbor.