Characteristics of Macrofaunal Communities and Benthic Ecological Quality Assessment in the Coastal Waters of Qingdao

In order to reveal the characteristics of macrofaunal communities and evaluate the benthic ecological quality in the coastal waters of Qingdao, macrofaunal samples were collected at 12 sampling sites in this area in June and October, 2021. A total of 110 macrofaunal species were found, including 50 species of polychaetes, 40 species of crustaceans, 13 species of mollusks, 4 species of echinoderms, 1 species of nemerteans, 1 species of hemichordates and 1 species of chordates. Polychaetes, crustaceans and mollusks were the three dominant groups. Prionospio queenslandica (polychaete) was the most dominant species in the 2 sampling seasons. Both abundance and biomass of macrofauna showed a decreasing trend from the northwest nearshore area to the southeast offshore area. CLUSTER analysis showed that the macrofaunal communities in summer and autumn in the study area could be divided into two groups and one independent site. BIOENV analysis showed that the combination of salinity and sediment water content, as well as the combination of bottom water dissolved oxygen and sediment median particle size, were the best combinations of environmental variables to explain the structure of macrofaunal communities in summer and autumn, respectively. Results of the Shannon-Wiener diversity index and abundance-biomass comparison curves showed that the benthic ecological environment in the coastal waters of Qingdao was greatly disturbed. The benthic ecological quality in the study area was poor, and it was worse in autumn than that in summer.