It is concluded that some diatom taxa satisfied the indicator
selection criteria for some ecological parameters, e.g., C. placentula,
A. minutissimum, F. construens var. venter, Navicula
atomus and Nitzschia gracilis. Moreover, the application of
diatomic indices developed in foreign country cannot be applicable
in Egyptian environment and the development of indices
based on the Egyptian ecoregions is very necessary.