Abstract: Based on the mollusk density data from quantitative sampling, and choosing tidal flat and season (method 1), mangrove and season (method 2), and mangrove and tidal flat (method 3) as the combinations of environmental factors to decide the spot number of environmental resources, this paper calculated the niche breadth and niche overlap of mollusk species in Zhanjiang Mangrove Nature Reserve by using Shannon-Wiener and Pianka formula. The results showed that the niche breadth of the mollusk species calculated by the methods 1, 2 and 3 was 0-1.96, 0-2.16 and 0-1.64, and the niche overlap at 0-0.1, 0.1-0.5 and > 0.5 among the species accounted for 25.1%, 32.8% and 21.6%, 31.6%, 362% and 223%, and 43.3%, 31% and 56.1%, respectively, suggesting that the niche overlap calculated by method 3 was bigger than that by other two methods. The hierarchical cluster dendrogram and MDS ordinal configuration of mollusk species also verified the difference of the three methods. Comparing the calculated results with actual quantitative sampling data, the analysis method of using mangrove and season to decide the spot number of environmental resources was in accordance with the reality, which was feasible for the niche study of mollusk in mangrove area.

Key words: Spectrophotometer detection, Benzalkonium bromide, Seawater, Algaecide, Red tide