Community structure and species diversity of intertidal benthic macroalgae in Fengming Island, Dalian

We investigated the community structure, seasonal variation, species diversity, and ecological niche of the intertidal benthic macroalgae community in Fengming Island, Dalian, China. Five sampling sites were established in the study area, and investigations were conducted in July 2010, April and October 2011, and January 2012. Species diversity index, cluster analysis, Levin's index, and Pianka's index were applied to determine species diversity and ecological niche. A total of 74 species were identified, of which, 15 belonged to Chlorophyta, 15 belonged to Phaeophyta, one belonged to Cyanophyta, and 43 belonged to Rhodophyta. The transverse distribution of the macroalgae species varied among the different sampling sites and seasons. In the longitudinal distribution, the low-tide zone had the highest abundance of species, which were predominately Rhodophyta; the mid-tide zone ranked second in the abundance of species, which were predominately Phaeophyta; and the high-tide zone had the lowest abundance of species, which were predominately Chlorophyta. Seasonal species number followed the pattern spring > summer > winter > autumn. Rhodophyta species were the most abundant in all four seasons, followed by Chlorophyta and Phaeophyta species, with Cyanophyta species being the least abundant. The benthic macroalgae in the study area were primarily temperate species, with the warm temperate composition greater than the cold temperate composition. Biomass distribution in each study site showed seasonal variation, and followed the pattern summer > spring > autumn > winter. Species diversity and cluster analysis demonstrated obvious seasonal variations, with the species diversity, evenness, and species richness indices higher in spring and summer than those in autumn and winter. Species diversity also varied among sampling sites. The function and status of different algae in the ecosystem were defined by the niche breadth and overlap results.