Effect of water motion and microhabitat preferences on spatio-temporal variation of epiphytic communities: a case study in an artificial rocky reef system, Laoshan Bay, China.

Epiphytic fauna community structure is mainly determined by macro-scale environmental characteristics (e.g., water motion), whereas the influences of, and interaction with, micro-scale habitat-forming species are not well known. In order to explore the effects of water motion and functional macroalgal group on the community structure of epiphytic faunas, macroalgae and epiphytic faunas from four isolated artificial rocky reefs with different levels of hydrodynamic conditions were investigated in Laoshan Bay of China. A total of 32 macroalgal species and 22 faunal species were recorded on the surveys. The biomass and abundance of macroalgae and epiphytic faunas showed significant variations among stations and months. The biomass and abundance of epiphytic faunas were highest at outer Huangshankou station (H1) with medium hydrodynamic force. The lowest biomass of epiphytic faunas occurred at inner Huangshankou station (H3) with highest level of water motion, while the lowest abundance of epiphytic faunas occurred at Liepo station (L) with lowest level of water motion. Results showed that medium water motion level contributed to increasing biodiversity of epiphytic faunas. Epiphytic communities generally presented higher biomass and abundance in summer than in spring or autumn, which indicated temperature could be the ecological driver for temporal variation of epiphytic communities. The epiphytic faunas showed distinct preferences to structural morphology of macroalgae which forms suitable habitat for these organisms. This study suggests that artificial rocky reefs are of great significance to restore and maintain coastal biodiversity, and appropriate physical disturbance promote community reestablishment.