Application Of Molecular Technology In Fish Diet Analysis And Intestinal Microflora Analysis In Ma’an Archipelago

Belanger’s croaker(Johnius belengerii) is a fundamental fish species of family Sciaenidae which usually has high gastric vacuous rate during 24 hours trawl surveys making the diet analysis difficult to continue, but plays an important role in the predatorprey relationship in the food web of Ma’an Archipelago, Eastern China Sea. In this study, we use visual inspection and DNA barcoding technology combined previous collected data to make more comprehensive analysis towards its diet compositions hoping to contribute to understand real natural mechanisms which could turn our coastal environment into feeding habitat. We amplified mitochondrial cytochrome oxidase subunit I(COI) using vertebrate and invertebrates universal primers in sampled fish stomach contents which could not be identified by morphological observation. Our results indicated that using DNA barcoding could successfully identify those partial digested food compositions species, such as Solenocera crassicornis, Alpheus distinguendus, Palaemon macrodactyl, Alpheus japonicus, Acetes chinensis. We found belenger’s croaker mostly feed on shrimps(frequency of occurrence, 45%) and crabs(23%), some juvenile fishes(27%) occasionally and among of them Solenocera crassicornis, Palaemon macrodactyl, Portunus sanguinolentus, Oratosquilla had not been observed in summer investigation ever before. In conclusion, the accurate and sufficient diet analysis is the precondition of feeding habit research which could contribute to reasonable suggestions of the management of island reef area ecosystem and fisheries forecasting.Different fish has developed their own special bacterial community in their gut during long time evolution. What’s more, the specific microflora plays an important role in fish intestinal ecological balance, especially in nutritional requirement, immunity function, phylogenetic and so on. We used Miseq platform to amplify 16 S rDNA V3-V4 region and analyzed the intestinal bacterial diversity. The results show that there’s six main bacterial phylum in our target fish, Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, Chloroflexi. Acidobacteria. Gammaproteobacteria takes the most part in Proteobacteria phylum and Chloroflexi toghether with Acidobacteria also appeared in the result. In a word, fishes focusing on different preys own themselves intestinal microbiota. We used QIIME(Quantitative In Sights Into Microbial Ecology) to analyze microbiota biodiversity and the difference of the bacteria among fish guts. The microbiota feature of different fishes performs good relationship with the fish diet instead the tropic level. The analysis of general structure feature of microbiota is necessary and should be considered in aquaculture, fish disease control and the development of microbiological additives.