Preliminary Study On Fish Diversity In Laizhou Bay Based On Environmental DNA Technology

In order to understand the species composition of main fish communities in Laizhou Bay,monitor and protect their diversity,environmental DNA(e DNA)technology and traditional survey methods were used to analyze the species diversity of fish in Laizhou Bay.Samples were collected from 12 stations in Laizhou Bay for 4seasons.Through the comparison and analysis with the traditional fishery resources investigation methods,the monitoring effect of e DNA technology was explored.The results showed that:1.According to the investigation results in autumn of 2020,11 orders,21 families,28 genera and 32 species of fish were detected.The dominant species was Cynoglossus joyneri,and the common species included Sebastes schlegelii,Thryssa kammalensis,Larimichthys polyactis,etc.2.In spring and summer of 2021,11 orders,17 families,19 genera and 33 species of fish were detected in spring and 13 orders,22 families,27 genera and 36 species of fish were detected in summer.In the spring of 2021,the dominant species included Scomberomorus niphonius,Larimichthys polyactis,Platycephalus indicus,Thryssa kammalensis,etc.;In summer of 2021,the dominant species included Sardinella zunas,Scomberomorus niphonius,Thryssa kammalensis and Engraulis japonicus.3.According to the investigation results in autumn of 2022,11 orders,17 families,22 genera and 26 species of fish were detected.The dominant species were Larimichthys crocea,Gymnoscopelus nicholsi,Tridentiger nudicervicus,etc.RDA analysis between environmental factors and fish diversity showed that the survival of different fish species depended on different environmental factors.For example,Larimichthys crocea and Mallotus villosus were mainly affected by phycoerythrin B-PE and chlorophyll Chl content;Sardina pilchardus and Muraenesox cinereus were related to conductivity SPC and salinity S;However,Acanthopagrus schlegelii was mainly affected by dissolved oxygen DO content,and showed a positive correlation.4.19 species of fish were found in dragnet(2 orders,5 families and 7 genera),which was 78 species less than that by e DNA investigation.Among them,there are 9species in autumn of 2020,which are dominant species according to IRI,and Sebastes schlegelii as well as Synechogobius ommaturus were absolutely dominant species.5species were found in the spring of 2021,among which Sebastes schlegelii,Ctenogobiusgiurinus,Hexagrammos otakii and Chaeturichthys stigmatias were the absolute dominant species.10 species were found in autumn of 2022,among which Cynoglossus joyneri,Thryssa kammalensis and Kareius bicoloratus were the absolute dominant species.5.In this study,four diversity indexes were used to reflect the Alpha diversity in the survey area.It is found that the diversity of fish community fluctuates significantly,and the diversity and quantity of fish are the highest in summer.The diversity index in spring is higher than that in autumn.There are significant differences in fish community composition and diversity at different sites.In conclusion,this study shows that e DNA technology has wide application potential in fish resources monitoring,which can obtain fish information more quickly and comprehensively,covering a larger spatial and temporal scale.This study provides an efficient new monitoring method for fish resources monitoring in Laizhou Bay.