DIVERSITY OF THE GENERA OF PENNATE DIATOMS IN THE PUNJAB

Twenty nine genera of algae belonging to 15 families of the phylum Bacillarophycota were collected during December 2003 and July 2006 from different freshwater habitats in various districts of the Punjab Province of Pakistan. Among them family Pinnularaceae with 19 species was most commonly found (25.33 %), next to it were the families Cymbellaceae (13.33 %), Naviculaceae (13.33 %) and Nitzschaceae (12 %) with 9 or 10 species each. The genera Cymbella with 10 species (13.33 %), Nitzschia with 9 species (12 %), Navicula and Pinnularia with 8 species each (10.66 %) occurred most commonly. About 64 % of diatoms were found as epiphytes, 22.66 % as planktic and epiphytic both, and 13.33 % as pure planktic individuals. Greatest proportion of collections (89.33 %) were made from Lahore City and its neighbouring areas, which was followed by the districts of Gujranwala (24 %) and Kasur (20 %). Most of the diatoms were collected in winter (42.66 %), smallest number of them were found in autumn (10.66 %), while in rest of the two seasons they occurred in almost equal proportions (25.33 & 26.66 %).