Abstract: Typhoon Doksuri caused extreme rainfall in the Beijing-Tianjin-Hebei region, and the Haihe River had a large regional flood. As the artificial flood drainage channel of the lower reaches of Daqing River in the Haihe River basin, the Duliujian River is responsible for the important task of discharging flood into the sea. The influx of flood made the salinity of the coastal waters decrease rapidly, which seriously affected the ecological environment of the sea area and the beach in the estuary area. Shellfish play an important role in the benthic ecosystem of the intertidal zone in the estuary area, and play an important role in the material circulation and energy flow of the Marine ecosystem. In order to understand the impact of the super typhoon on the intertidal shellfish resources in the river estuary, 15 sampling points in this area were investigated in the early, middle and later stages of flood discharge. The results showed that the salinity of the sea water in this area decreased from 20 to about 13, and finally recovered to 25. A total of 17 species of shellfish were found in the three surveys, belonging to 2 classes, 3 subclasses, 9 orders and 13 families. The shellfish species obtained from the three surveys were 15, 8 and 8 kinds, respectively. The biomass of the three surveys were 252.77 g/m², 352.56 g/m² and 845.66 g/m², respectively. Diversity index H´ : late flood discharge>middle flood discharge>early flood discharge; Richness index D: early flood discharge>middle flood discharge>late flood discharge; Evenness index J: late flood discharge>middle flood discharge>early flood discharge. Affected by the flood discharge, the species and distribution characteristics of the intertidal shellfish fluctuated, and the biomass was greatly affected in the early and middle period of the flood discharge, but the dominant economic shellfish, Mactra veneriformis, was less affected by the flood discharge, and recovered quickly in the late period of the flood discharge, with the biomass reaching 712.65 g/m². The results of this survey can provide reference for the assessment of the damage caused by Typhoon Doksuri to the shellfish resources in Tianjin, and also provide a theoretical basis for the subsequent restoration and value-added release of shellfish resources.

Key words: typhoon Doksuri, Duliujian River, shellfish, community structure, ecological diversity