One hundred and eleven identified and seven unidentified species in addition to 5 varieties belonging to forty-three aquatic fungal genera were recovered from 452 soil samples collected randomly from different localities in Nile Delta and Suez canal regions including eleven governorates. The investigated soil samples were collected seasonally during the period from autumn 1990 to summer 1991 (1 13 samples each season). The richest season (85 identified and 5 unidentified species in addition to 2 varieties) in aquatic fungi was the winter season (10.0-15.5 "C) whereas the poorest (32 identified and 5 unidentified species in addition to one variety) was summer (24.0-27.5 "C). The richest soil samples in aquatic fungi were those of low or moderate temperature seasons, high contents of organic matter and considerably poor in total soluble salts. The pH value did not show any regular seasonal variation and did not exhibit any considerable influence on fungal populations. Some aquatic fungal genera and species were disappeared completely in certain seasons and vice versa.
The most dominant aquatic fungal genera were Pythium, Allomyces, Aqualinderella and Nowakowskiella. The commonest aquatic fungal species were Allomyces anomalus, Aqualinderella fermentans, Nowakowskiella elegans, Blastocladiopsis parva and Dictyuchus sterilis.
The seasonal fluctuations of aquatic fungi were followed in various parts of the world (e.g. COKER 1923 and HUGHES 1962 in U.S.A., IVIMY-COOK and MORGAN 1934, SPARROW 1957 and I. Oomycetes Achlya A. camliniana A. debaryana A. dubia A. jlagellata A. hypogyna A. klebsiana A. oblongata A. oblongata var. gigantica A. prolifera A. proliferoides A. racemosa Achlya species Aphanomyces A. helicoides A. laevis A. norvegicus A. ovidestruens A. parasiticus A. scaber Aphanomyces species Apodachlya A. completa Aqualinderella A. fermentans Botrytis B. infestans Brevilegnia B. longicaulis B. u n i s p e m Brevilegnia species D. carpophorus D. monosporus D. polysporus D. sterilis Geolegnia G. injlata Leptolegnia L. caudata L. chapmanii L. subterrarzea Leptornitus L. lacteus L. pyriferus Olpidiopsis 0. pythii 0. saprolegniae var. levis 0. varians Table 1 (Continued) Species Seasons Total Autumn Winter Spring Summer Occur-Percen-O.R. rence a g e % A. mucrogynus A. monilifonnis A. monspeliensis Blastocladia B. angusta B. pringsheimii Blastocladiopsis B. parva Catenaria C. allomycis Chytridium C. hyalinum Chytriomyces C. annulus Cladochytrium C. hyalinum C. replicatum C. tenue Coelomomyces C. pentangulatus C. psorophorae C. punctatus C. stegomyiae Gonapodya G. prolifera Myiophagus M. ucrainiaca Nowakowskia N. hormothecae Nowakowskiella N. atkinsii N. crassa N. delica N. elegans N. hemisphaerospora N. multispora