Analysis On Fish Community Structure In Different Sub-habitats Of Jiuduansha Wetland Of The Yangtze Estuary

The habitat of Jiuduansha Wetland in the Yangtze River Estuary is unique and diverse.It has different sub-habitats such as tide ditch,salt marsh wetland and light beach.It provides habitat for many aquatic organisms to survive,and the fish biodiversity is very high.Studying the structural characteristics and changes of fish communities in Jiuduansha Wetland is of great theoretical and practical significance for understanding the biological diversity of the Yangtze Estuary and its maintenance mechanism,and the sustainable output of fishery resources.This study focused on three types of sub-habitats such as the tidal ditch,ribbed weedland and light beach of Jiuduansha Wetland.Through continuous field investigations,the structural characteristics of fish communities in different sub-habitats and the distribution and growth of the dominant species,Chinese perch,were analyzed.Regularly,the results are as follows:(1)Structural characteristics of fish communities in different sub-habitats of Jiuduansha WetlandFrom May to October 2019,a total of 2081 fish samples were collected in three sub-habitats including Jiuduansha Wetland Tidal Gully,Weeping Grass and Guangtan from May to October 2019.They belong to 8 orders,19 families and 42 species.The analysis found that the fish species in the Jiuduansha wetland include four types of freshwater fish(8 species),marine fish(13 species),estuarine settled fish(17 species)and migratory fish(3 species).The number of fish species in the Guangtan sub-habitat was the highest(33 species),followed by the tidal ditch sub-habitat(26 species),and the number of species in the ribbed sub-habitat was the least(22 species).There are 6 dominant species in the three sub-habitats,which are: Liza haematocheila,Lateolabrax maculatus,Coilia nasus,Nibea albiflora,Larimichthys polyactis and spot tail Goby(Acanthogobius ommaturus),among which Chinese flower bass is the dominant species.The number and diversity of fish species in the Guangtan sub-habitat were higher than that of the scallion and tidal groove sub-habitats,while the number and biomass of the individuals showed that the tidal ditch sub-habitat was higher than that of the Guangtan and ribbed grass.The corresponding quantity-to-quantity relationships of fishes in the sub-habitats of Guangtan,Ribes nigra and tidal ditch have obvious monthly changes,but the correlation and differences between the three sub-habitats are not significant.(2)Distribution and growth characteristics of dominant species of Chinese perch in different sub-habitatsThere are obvious spatial and temporal differences in the distribution of Chinese flower bass in three sub-habitats such as tidal ditch,ribbed weed and Guangtan.From the perspective of abundance in the sub-habitat,the tidal ditch sub-habitat is the highest,followed by the striated sub-habitat.Guangtan sub-habitat is the lowest;from day to night,the abundance of Chinese perch during night tide is greater than that of day tide.The growth of Chinese perch in Jiuduansha Wetland belongs to uniform growth.With the change of the month,the body length and body weight increase significantly,and the growth in different sub-habitats is relatively stable.The Chinese perch in Jiuduansha Wetland is basically larvae,and the selected habitat is mainly tidal ditch,which shows that the night activities are more frequent.In summary,Jiuduansha Wetland has a rich fish composition in different sub-habitats,with 4 ecological types.The dominant species are mainly migratory,estuarine settlement and marine fish.Among the fish communities in Jiuduansha Wetland,fish larvae are the main species,and tidal ditch and ribbed wetland are selected as the key habitats.The diverse habitats of Jiuduansha Wetland provide good feeding and growth conditions for fish larvae,which is an important reason for the high biodiversity in this area.