Abstract:

The niche breadths and overlaps of 24 dominant phytoplankton species in the Lake Chaohu in March 2008 were measured using corresponding formulas respectively,and the ecological influence among all the dominant species and the relationships between phytoplankton species and ambient environment were discussed in this paper.The results showed that the niche breadths of 〖WTBX〗Stephanodiscus astraea,Cryptomonas erosa〖WTBZ〗，〖WTBX〗Melosira granulata〖WTBZ〗,etc.in the east of Lake Chaohu exceed 3,and in the west of Lake Chaohu,the algae with greater niche breadth are 〖WTBX〗Stephanodiscus astraea,Cryptomonas erosa，Cryptomonas ovata〖WTBZ〗,etc.The results showed that selecting the phytoplankton with wide range of niche breadths as indicator is more reliable.Thus we take 〖WTBX〗Melosira granulata,Anabaena flosaguae〖WTBZ〗 and 〖WTBX〗Asterionella〖WTBZ〗 sp.as indicators in the west area of Lake Chaohu.The niche overlaps suggest that 〖WTBX〗Chlorella pyrenoidosa〖WTBZ〗 is developing fastest in the east area of Lake Chaohu,while 〖WTBX〗Chlorella pyrenoidosa〖WTBZ〗 set a fast pace in the west area.The abundance of developing phytoplankton in the east area is greater than that in the west area.These species are growing faster,and most of them can tolerate polluted environment.Subsequently,comparing phytoplankton community structure of the Lake Chaohu in April with that in March,we can draw a conclusion,namely it is reliable to forecast the surface water bloom of Anabaena flosaguae by niche calculation.〖