The present study illustrates the evaluation of certain environmental parameters and some heavy metals in 27 sites at three Nile Deltaic Lakes, namely, Manzalah, burullus and Idku, during 2003 and their influence on the diversity of their inhabiting invertebrates and fish. Lowest levels of dissolved oxygen and highest values of biochemical oxygen demand, Cd and Pb were recorded in Lake Manzalah, respectively. Lake Idku recorded the highest concentrations of phosphate, ammonium, nitrate, nitrite, Cu and Zn. Lowest values of heavy metals in water were recorded at Lake Burullus. Total nitrogen, total phosphorus, Cd, Pb, Cu and Zn in sediment were much higher than their concentrations in water. The order of abundance of heavy metals in water and sediment was as follows: Zn>Cu>Pb>Cd. The density of invertebrate species in sediment were 24 , 24 and 16 species in Lakes Manzalah, Burullus and Idku, respectively, Nelanoides tuberculata and Biomphalaria alexandrina showed the highest density. Both lake Manzalah and Burullus showed the highest density (612 individual /m2 and 527 individual / m2) of Melanoides tuberculata, while average densities of Biomphalaria alexandrina in Lakes Manzalah, Burullus and ldku were : 40 , 27 & 60 individual/ m2, respectively, due to the highly pollutants of sewage, which is very hazardous to the public health. Twenty six fish species were recorded at Deltaic lakes, while the marine fishes were not reported at Lake Idku. Statistical analysis indicated that heavy metals concentrations showed significant differences within sites and environmental parameters (P<0.05). DECORANA ordination of deltaic lakes and Dendrogram analysis of invertebrate and fish diversity were correlated in the deltaic lakes. However, monitoring programs should continue in order to maintain the quality of the Nile Deltaic lakes environment.
