Abstract:

The objectives of this study were to reveal fluctuations in the macrofaunal biodiversity and to provide a scientific basis for sustainable exploration of biological resources in the southern waters of the Miaodao Archipelago. Accordingly, in November 2012, February 2013, May 2013 and August 2013, four cruises were carried out in this area to investigate patterns in macrofaunal biodiversity. Shannon-Wiener diversity index, species evenness and richness indices were compared to investigate biodiversity patterns. Meanwhile, species composition and dominant species of macrofauna were also estimated. A total of 164 species of macrofauna were identified, including 82 species of polychaetes, 38 species of crustaceans, 30 species of mollusks, 9 species of echinoderms, and 5 species from other phyla. The species number of each station ranged from 6 to 42. Numbers of species in summer and winter were higher than in spring. No seasonal differences in Shannon-Wiener diversity were detected. Pielou’s evenness index was highest in summer and spring. The species richness index was slightly lower in spring and in summer. It was revealed that the number of species and the abundance had great effects on macrobenthic species diversity, while some environmental factors correlated closely with biodiversity. Sediment levels of organic matter and chlorophyll were the main factors affecting biodiversity of macrofauna, through their influence on number of species and evenness. According to abundance-biomass comparison curves (ABC curves), macrobenthic communities at Station C13 (between Miao Island and Beichangshan Island), Stations C17 and C28 (close to Miao Island) were affected by moderate disturbance. Disturbance was not detected at the other stations in the study area.

Key words: Miaodao Archipelago, macrofauna, biodiversity, ABC curves, sediment