Phytoplankton Diversity of Algae in Suganhu Lake in Gansu Province

We aimed to research the phytoplankton resource that lied in the special geography position and climate conditions like Suganhu Lake,so as to protect species resource in marsh.Samples were collected three times during spring(May),summer(Aug.) and autumn(Oct.) in 2006.We have found 61 species(including varieties) in the big Suganhu Lake.Most of them belong to Bacillariophyta,about 37 species and 18 genera.Meanwhile,Cyanophyta constituted by 15 species and 11 genera;Chlorophyta made up of 8 species and 7 genera;Only 1 species and 1 genus existed in Pyrrophyta;However,about 68 species(including varieties) have been found in the small Suganhu Lake;Nearly 42 species and 16 genera in Bacillariophyta.13 species and 9 genera in Cyanophyat;11 species and 6 genera in Chlorophyta;Only 1 species and 1 genus fall into Pyrrophyta and Euglenophyta respectively.In conclusion,Bacillariophyta is the dominant phylum all the time.Nevertheless,Cyanophyat and Chlorophyta began to overgrowth in August.The results indicated that some peculiar dominant genera appeared in different seasons.The dominant genera were Cymbella(Synedra),Cyclotella(Nitzachia),and Gloeothece(Fragilaria) respectively in spring,summer and autumn in the Suganhu Lakes.Amphora oralis,Navicula oblonga,Choroococcus limneticus are dominant species that always emerged.The most explainable reason for the variation of these community is that all determined by the lake salinity and temperature.