Ecological niche analysis of dominant species of phytoplankton in Lake Changhu, Hubei Province

Abstract

In order to examine the characteristics of community structure of phytoplankton in Lake Changhu, a survey started in April, 2012 and ended in January, 2013. Using Niche Breadth Index modified by Levins and Colewll and Levins Niche Overlap Index, ecological niche of dominant species of phytoplankton was determined. Relationship between the distribution of dominant species in sampling sites and associated environmental parameters and ecological niche was analyzed. Results showed that: dominant species varied with the seasons, and species belonging to Cyanophyta and Chlorophyta was the most abundant with broader niche breadth and larger biomass and dominant index than other species. Based on dominant index and niche breadth, the dominant species in the investigation could be divided into 3 classes, Chlorella vulgaris and Cyclotella comta were dominant species in all the four seasons and possessed broader distribution and wider niche breadth, and had a better usage on environmental resource. Oscillatoria amphibian, belonging to Cyanophyta, as the main dominant specie in summer, had the largest biomass in all the sampling sites. Since being restricted by interspecific competition and higher hydrophyte, it didn't get absolute advantage in completion. Other species became dominant species in seasons now and then. T-test analysis results showed that wastewater discharge from intake and outlet around Lake Haizihu and high density enclosure culture in Mahongtai area and Lake Yuanxinhu led to difference in concentrations of total nitrogen and total phosphorus among the three areas. Correlation analysis between environmental parameters and abundance of dominant species indicated that temperature and N/P were main factors influencing the distribution of phytoplankton.