关键词: 鱼类, 多样性, 群落结构, 乐清湾口

Abstract: In order to study the dynamic change trend of community structure and the status of the fishery resources in Yueqing Bay mouth, the species composition, species number, diversity of fish communities was studied. A total of 49 species were identified, which belonged to 39 genera in 26 families of 10 orders, and species number in autumn is higher than spring. The species numbers in spring were less than that in autumn especially in Oujiang estuary, and the general spatial distribution trend of fish species in autumn was from east to west. The  diversity in weight of the species in spring was lower than that in the autumn, while the individual diversity wass higher than that in autumn. There was obvious correlation between species number and diversity indexes. The study showed that fishes species types  mainly belonged to inshore estuary species and most of them were eurythermic and oligohalabous species in Yueqing Bay mouth, because this area was adjacent to Oujiang estuary which has much runoff volume.  Due to the effect of geographical position and hydrological environment, there were more warm-water species The characteristic of the general plane distribution was that the species is more rich in autumn than that spring,  which was affected by the freshwater masses in spring, and Taiwan warm current confronted with Zhejiang coastal current in autumn. The cause of difference of fish community diversity in between spring and autumn mainly was that the fish size and quantity changed with seasons.

Key words: fish, diversity, community structure, Yueqing Bay mouth