Distribution pattern of pennate diatoms in the north-eastern areas of Pakistan.

摘要

Seventy-five species of planktic and epiphytic algae with solitary or colonial organizations, belonging to 36 genera and 15 families of the order Bacillariales, phylum Bacillariophycota, have been collected from various freshwater habitats of Pakistan during December 2003 and July 2006; among them, 12 genera and 29 species were new records for Pakistan. The family Pinnulariaceae with 20 species was most commonly found (25.34%), next were the families Cymbellaceae (13.33%), Naviculaceae (13.33%), and Nitzchiaceae (12%) with 9 or 10 species each. The genera, Nitzschia with 9 species (12%), Cymbella, Navicula, and Pinnularia with 8 species each (10.33-10.67%) occurred most commonly. About 64% diatoms were found as epiphytes, 22.66% as planktic and epiphytic, and 13.33% as pure planktic individuals. The greatest proportion of the collection (49.33%) was made from Lahore city and its neighboring areas, which was followed by the districts of Gujaranwala (18.66%) and Kasur (20%). Most of the diatoms were collected in winter (42.66%); the smallest number of them was found in autumn (10.66%), while the rest occurred in the other 2 seasons, where they were found in almost equal proportions (25.33% in summer, 26.66% in spring).