Community structure and distribution characteristics of shellfish in the coastal waters of Zhejiang

Abstract:

In order to understand the community structure and distribution characteristics of macrobenthic shellfish in the coastal waters of Zhejiang, the fixed-point bottom trawl fishery resources survey was conducted from August 2020 to April 2021. The surveyed sea was divided into two areas, the northern and the southern part in Zhejiang, with 29°N as the boundary. A total of 41 species of shellfish belonging to 25 genera, 25 families and 6 orders were collected and identified. The absolute dominant species in all seasons were Bursa rana and Turritella terebra bacillum. There were obvious regional differences in number of species and shellfish biomass distribution in the north and the south areas during different seasons. The shellfish biomass for spring and autumn was higher than that for summer and winter, and it decreased from the north to south area in other seasons except summer. In summer, differences in the average biomass of shellfish were not found in the north region and the south areas. In terms of diversity analysis, The richness index (D) and the diversity index (H') were the highest in spring and the lowest in summer, and the evenness index (J') was the highest in winter and the lowest in spring. Hierarchical Cluster analysis (Cluster) results showed that the shellfish communities were divided into 3 groups at 60% similarity level in Zhejiang coastal waters. Group Ⅰ was in the southern area in spring, summer and autumn, Group Ⅱ was in the northern area in spring, summer and autumn, and Group Ⅲ was the whole area in the winter, and there were differences in the north and the south areas in spring, summer and autumn. The stress value of non-metric multidimensional analysis was 0.08, which had explanatory significance. CCA analysis showed that depth and bottom sea temperature had significant effects on benthic shellfish distribution. This study can provide some reference for shellfish biodiversity conservation and sustainable use for shellfish resources in the coastal waters of Zhejiang.