PHYTOPLANKTON DIVERSITY IN SOME PONDS AT NEW DAMIETTA -EGYPT

Phytoplankton diversity and biomass in five ponds at New Damietta (El-Ladamin; Western New Damietta 1, W1; Western New Damietta 2, W2; Eastern New Damietta 1, El; and Eastern New Damietta 2, E2) differed in salinity and pollution level were studied over a full year (from January to December 1998) relative to irrigation water (Halawa canal). Salinity was low at Halawa canal and El-Ladamin pond but high at Western and Eastern New Damietta ponds. These results were in agreement to great extent with hardness, alkalinity and contents of nitrate, phosphate, sulphate, sodium, potassium, copper and zinc but inversely proportional with dissolved oxygen. However, 136 of algal taxa were identified at the irrigation canal, 120 at El-Ladamin pond, 107 at WI , 64 at W2, 13 at El and only 12 at E2. Phytoplankton standing crop of Halawa canal and El-Ladamin pond was mainly due to Euglenophyta and Bacillariophyta but due to Dinophyta and Cyanophyta at W1, to Cyanophyta, Dinophyta and Bacillariophyta at W2 and exclusively to Chlorophyta or Cyanophyta blooming at El or E2, respectively. Diversity index indicated that Halawa and El-Ladamin water was slightly polluted while the Western ponds (W1 and W2) were moderately polluted but the Eastern ponds (El and E2) were heavily polluted. Saprobic situation revealed that irrigation water located in a—oligosaprobic zone, El-Ladamin in f3"-mesosaprobic, the Western ponds in a—mesosaprobic and the Eastern ponds in a-polysaprobic. Compound eutrophication indicated that nature of water was eutrophic at Western and Eastern ponds but mesotrophic at Halawa bay and El-Ladamin pond.