Analysis Of The Fish Diversity Of The East China Sea And The Yellow Sea In Winter Using Environmental DNA

The conservation of biodiversity is of great important for the stability of ecosystems and human societies.For the monitoring of biodiversity in marine ecosystem,traditional methods are mainly depends on fishing surveys,such as net,which were labor and time-consuming.Environmental DNA(eDNA)are free DNA molecules produced by the shedding of skin,feces,saliva,gametes,secretions and some other ways.Many researches have shown that the biological diversity and resource had significant correlation with the natural diversity and biomass.In this study,the eDNA method was used to evaluate the biodiversity and resources of the East China Sea and the Yellow Sea.The main results are as follows:1.The high-throughput sequencing method was used to detect the diversity and abundance information of 10 sites in the southern part of the Yellow Sea and the northern part of the East China Sea.The results were as follows: The high quality sequences of these 10 sites was between 3,555,209 to 5,931,287,which can be clustered into 3838 OTUs.After deletion of the un-intended sequences,the number of effective sequences was 3042,accounting for 88.30% of OTU.A total of 100 species of fish were identified in 10 stations,which categorized into 85 genera,53 families,19 orders and two classes.The species of southern part of the Yellow Sea is 72,belonging to 51 genera,38 families,15 orders and one class;for the northern part of the East China Sea,the number were 91,belonging to 77 genera,48 families,18 orders and two classes.The total number of fish species in 10 sites was approximatly 571 which was estimated depend on the analysis of OTUs with identity value of more than 97%,and these species belonging to 117 families,26 orders and two classes.These fish species were most common spcies or recorded before in the East China Sea.The biomass results from eDNA had a well correlation with the traditional methods,with the higher capture species also has a higher eDNA amount.These things all together suggested that eDNA used in fishery suvey was feasible.Then,results from eDNA were used to analysis the diversity of 10 sites.Results showed that the East China Sea was higher than that in the southern part of the Yellow Sea in the the number of species and diversity index aspects.The abnormal was C04(E125゜N31゜)which has a relative low number of species and α diversity index.Further investigation for this site was recommended.The β diversity index at latitude 35 degrees shown that replacement rate of species is accelerated with the increase of distance from the coastline.In addition,this study also detected two rare fish species,which is Chinese sturgeon and Chinese bahaba and also made a prediction for their relative distribution.2.A pair of primers which is specific to Harpodon nehereus was designed and used in the montoring of resouces of 18 sites.The results showed that this specie was mainly distributed at 31 and 32 degrees at north latitude,which is similar with the traditional surveys.Besides,results from qPCR has a significant positive correlation with the next generation methods.Further,the mitochondrial CO1 sequence and the 18 S ribosomal RNA sequence were evaluated in the metabarcoding research.The results showed that the mitochondrial CO1 primers designed was not suitable for the study of fish metabarcoding.CO1 as now the most widely used in the study of fish diversity of barcode,its application in environmental DNA research remains to be further exploration.More than 80% of the PCR products of 18 S primers were fish sequences.However,the acquired 18 S sequences were poorly specific,which means one sequences might be annotated as more than one species.Further studies also need to be conducted.3.In this section,we analyze the relationship between eDNA data and the related fishery data.The weight data from fishery investigation and high-throughput sequencing of 18 species of fish was modeled as Y = 1.40 + 0.31X(X represents the high throughput sequencing abundance,Y represents the fishery weight),the correlation coefficient R was 0.479,adjusted R2 was 0.215,and the test result was significantly correlated(P <0.05).The results showed that the linear relationship between anchovy was Y =-7.03 + 1.93 X,the correlation coefficient was 0.709,adjusted R2 was 0.420,and the test result was significant correlation(P = 0.046 <0.05).For the H.nehereus,after deletion of some exception value,the model was Y =-0.92 + 5.65 X,the correlation coefficient R was 0.735,the adjusted R2 was 0.463,and the test result(P = 0.038 <0.05).The results for the Setipinna tenuifilis was not significant.Combined with the dominant species analysis in section 1,this insignificance might results from the contamination in sampling.In summary,this study made a fundmentary exploration for the eDNA used in the monitoring of diversity and abundance in fishery management,and also compared the eDNA data and traditional methods,all the results suggested that eDNA method used in fishery monitoring is feasible,but also a lot of work need to be improve.At this stage we recommended eDNA survery as a supplementary means of monitoring traditional methods.