A Preliminary Study On The Community Structure Characteristics And Health Assessment Of Invertebrates In Tianjin Subsea Trawl

Tianjin coastal zone,located on the west coast of the Bohai Sea,has a broad coastal environmental capacity and rich fishery resources.It is not only an important culture area for fish,shrimp,crabs and shellfish in China,but also a "production room" for fisheries in northern China.Invertebrates represented by crustaceans have made great contributions to Tianjin offshore fishery resources.However,affected by human activities such as encirclement and reclamation,excessive fishing and other human activities,the spawning grounds and habitats of fish,shrimp and shellfish have been destroyed,and traditional economic invertebrates such as Penaeus chinensis and Portunus trituberculatus have basically failed to form a fishing season,and the fishery economy is suffering a serious impact.Therefore,based on the survey data of invertebrates in Tianjin coastal waters in 2018,2019 and 2020,combined with historical survey data,this paper makes a preliminary study on the characteristics of invertebrate community structure and health assessment in Tianjin coastal waters.The main results are as follows:A total of 43 species of invertebrates were identified,including 23 species in 2018,34 species in 2019 and 36 species in 2020.The main groups were molluscs and crustaceans,with significant interannual differences(P < 0.05).The main ecological groups are perennial settlement groups,and warm species such as Oratosquilla oratoria and Loligo beka are absolutely dominant in the sea area.Resource Mantissa and resource biomass were significantly different between years(P < 0.05),showing an increasing trend year by year.Compared with the historical data,there is little change in the perennial species and a decrease in the number of migratory species;the structure of the dominant species has changed;the invertebrate resources in the coastal waters of Tianjin are currently at a low level and there are obvious signs of decline,but the recovery of invertebrate resources in the coastal waters of Tianjin has improved in recent years.Through the analysis of the invertebrate community structure,it is found that the invertebrate community can be divided into two regional groups,and the regional distribution characteristics are obvious,and the invertebrate community diversity is increasing year by year,showing the characteristics of high species richness and uniform individual distribution.Compared with the historical data,the species of invertebrate community in the coastal waters of Tianjin changed from high richness and uneven individual distribution to high species richness and uniform individual distribution,and the invertebrate species community structure was maintained at a stable level.To a certain extent,it promoted the recovery of its resources.Based on the analysis of invertebrate resources and influencing factors in Tianjin coastal waters by GLM and GAM model,it is found that GAM model can better explain the response mechanism between invertebrate resources and influencing factors than GLM model.Under the comprehensive action of environmental factors such as temperature,dissolved oxygen,p H and redox potential,salinity and conditional factors month,longitude and latitude,only temperature is the main factor affecting invertebrate resources.This has a lot to do with the temperature characteristics of the dominant species of invertebrates in the coastal waters of Tianjin.The abundance / biomass comparison method(ABC curve)and marine biological index model(AMBI and M-AMBI)were used to evaluate the biological disturbance grade and marine environmental quality of invertebrate community in the coastal waters of Tianjin.It is found that compared with the single disturbance of ABC curve,AMBI and M-AMBI index have better applicability.And the results of each index show the same trend.according to the above principles,combined with the results of resource quantity and diversity,it can be known that the invertebrate species community in the coastal waters of Tianjin is slightly disturbed to undisturbed in 2018,2019 and 2020,and the eco-environmental quality is in a good to excellent condition.although the difference in ecogroup composition is small,the secondary opportunity species of pollution-tolerant EGIV in 2020 is higher than that in 2018 and 2019.And in recent years,the recovery trend of resources is obvious,and the invertebrate species community is relatively stable,maintaining a good situation.