Impacts of artificial reef on community structure and functional traits of macrobenthos near Furong Island, Shandong, China.

To evaluate the ecological restoration effect of artificial reefs and explore the impacts of artificial reefs age on the structure and functional traits of the macrobenthos community, two artificial reef areas with different reef ages in the coastal waters of Furong Island, Laizhou Bay were investigated in May, August, and October 2019. A total of 120 macrobenthos species were identified in the three seasons, including 72 species in the control area, 74 species in the artificial reef with short age (1 year), and 80 species in the artificial reef with greater age (4-5 years). was the dominant species in all areas. The biomass, abundance, Shannon diversity index, Margalef species richness index of macrobenthos communities were all in order of reef area with greater age > reef area with lower age > control area, and the biomass and abundance in the reef area with greater age were significantly higher than those in the other two areas. The composition and relative abundance of functional traits of macrobenthos communities in the reef area and the control area were different. However, the dominant categories of traits in different areas were consistent, including deposit-feeder, burrower, medium body size, medium life span, high body flexibility and infauna. The composition and relative abundance of functional traits of macrobenthos communities in the reef area and the control area were different mainly in feeding mode, habitat, and body size. The relative abundance of smaller individuals (1-3 cm) and suspension feeders in the reef area was higher than those in the control area, while predator abundance was lower, and such effect became more pronounced with increasing reef age. The reef area was significantly higher than the control area in functional diversity, but without significant difference in functional redundancy. The results of abundance/biomass comparison curve and marine biotic index showed that the benthic ecological quality in the study area was good. The macrobenthos community was slightly disturbed after 1 year of reef construction, while the conservation effect of macrobenthic resources and the benthic ecological quality were significantly improved after 4-5 years of reef placement.