Characteristics of Macrobenthos Communities and Status Quo of Branchiostoma belcheri tsingtauense Resources in Changli Sea Area, Hebei Province

In spring (May) and summer (August) of 2017, the community characteristics of macrobenthos and status quo of Branchiostoma belcheri tsingtauense resources were investigated in Changli Gold Coast National Nature Reserve, Hebei Province. The results show that 56 species and 50 species of macrobenthos were identified in spring and summer respectively, and most species in both seasons belong to Annelids. The average abundance of macrobenthos was 87.11 m^-2, while the average biomass was 11.13 g·m^-2; the average abundance of B. belcheri tsingtauense was 31.36 m^-2, while the average biomass was 1.44 g·m^-2. The body length of B. belcheri tsingtauense ranged from 0.50 to 4.45 cm, and most individuals were in Ⅱ-age and Ⅲ-age. The body weight ranged from 0.3 to 109.4 mg, and the dominant weight groups were >20-40 and 0-20 mg. The B. belcheri tsingtauense in the Changli sea area was small, compared with historical data; the amount of B. belcheri tsingtauense resources had been decreasing. The changes in biodiversity indices in spring and summer represented similar trends, and the average Shannon-Wiener Index indicates that the habitat quality was moderate. Both clustering analysis based on Bray-Curtis similarity coefficient and multi-dimensional scaling (MDS) were carried out to analyze the macrobenthic community structure in the two seasons. The macrobenthic community in spring was divided into 5 groups, while it was divided into only 2 groups in summer. The difference between community compositions was obvious, which indicates that the community structure changed greatly across seasons.