Trophic Structure Of The Major Species In Haizhou Bay Using Stable Carbon And Nitrogen Isotope Analysis

Food web and nutrient structure can reflect the health status of local fishery resources,and affect the material and energy exchange in the environment,it's the important factor of habitat ecological protection and exploitation.The use of stable isotope techniques to develop food webs and nutrient structures in different habitats has become a hot topic in this field.Since the establishment of the marine ranching in Haizhou Bay,there has been no systematic research report on nutrition ecology.Therefore,this paper studies the food web and nutrient structure of marine ranching in Haizhou Bay,which can continue to build Haizhou Bay Ocean Ranch to provide a scientific basis for decision-making.In this paper,the nekton,benthos,plankton,POM and SOM samples were collected in the three seasons(spring,summer and autumn)of the marine ranching of Haizhou Bay in 2014 and 2015,the composition of the dominant species and the seasonal variation of phytoplankton were carried out in the past two years by processing and analysising of major communities.The stable isotope technique was used to determine the carbon and nitrogen isotopic ratios of producers and consumers in the food web,the baseline organisms were determined and the trophic level was calculated.Finally,the IsoSource model and the carbon and nitrogen stable isotope quantification indexes were used to analyze the seasonal variation of the carbon source and nutrient structure of the consumers.The main results were as follows:1.According to the comprehensive survey of fishery resources in 2014,the dominant species in swimming biology community are mainly Oratosquilla oratoria,Larimichthys polyactis,Loligo chinensis and Chaeturichthys stigmatias.The main species are Oratosquilla oratoria,Glossaulax didyma,Chaemrichthys stigmatias,Alpheus japonicas,Oxyurichthy tentacularis,Tegillarca granosa,Trachypenaeus curvirostris,Brachytoma flavidulus,Parapenaeopsis tenella,Scapharca subcrenata,ostreagigastnunb,Raphidopusciliatus,Charybdis japonica and Clavatuia pseudopriciplis.2.The Bacillariophyta species were the most dominant species in the phytoplankton of 2014.The dominant species in the spring were Navicula,Prorocentrum minimum,Prorocentrum micans and so on,The dominance species of phytoplankton in summer were mainly Nitzschia pungens,Coscinodiscus granii and Coscinodiscus granii.The dominant species in the autumn were Chaetoceros curvisetus,Ceratium furca and Chaetoceros debilis Cleve.There were 7 species of zooplankton identified in 2014.The dominance species of zooplankton in spring were Acartia bifilosa.The dominance species of zooplankton in summer were Paraclanus parvus,and the dominant species of zooplankton in autumn were Sagittacrassa,Calanus sinicus,Labidocera enchaeta,Acartia pacifica and so on.3.The stable nitrogen isotopic ratios of fish in Haizhou Bay in the summer of 2014 were mainly in the range of 9.6 ‰ ~ 13.9 ‰,and the distribution of stable carbon isotope was in the range of-16.2 ‰ ~-23.3 ‰.The stable nitrogen isotope distribution of shrimp was 8.0 ~ 13.0 ‰,the stable carbon isotopes was between-16.5 ‰ and-20.5 ‰.The stable nitrogen isotopes of crabs are mainly between 8.2 ‰ and 12.9 ‰,and the stable carbon isotopes are concentrated from-17.8 ‰ to-15.8 ‰.The stable nitrogen isotopes of cephalopods were between 11.0 ‰ and 13.4 ‰,and the stable carbon isotopes were between-18.5 ‰ and-16.2 ‰.The stable nitrogen isotopes of bivalve concentrated between 7.5 ‰ and 9.8 ‰,the stable carbon isotopes were between-17.4 ‰ ~-16.4 ‰.4.The baseline organism was Sinonovacula constricta,and the isotope trophic fractionation was 3.4 ‰,using the trophic level formula,the trophic levels of fish species ranged from 1.9 to 3.9,with top predators Lateolabrax maculatus and Trypauchen vagina occupied the highest trophic level and the primary consumers Sinonovacula constricta and Acetes chinensis having the lowest ones.There was a significant positive relationship between body size and stable nitrogen isotope values for Oratosquilla oratoria exist,indicating an ontogenetic trophic shift during growth(R2=0.90,P<0.01).The carbon isotope values of organisms in Haizhou Bay suggested a large overlap in trophic niche among species.5.The stable carbon isotope values of consumers ranged from-18.9‰ to-17.1‰ in the spring of Haizhou Bay area,the stable carbon isotope values of 3 kinds of potential food sources ranged from-18.1‰ to-23.4‰.The IsoSource model results showed that the phytoplankton was the most important food source for consumers(80.8%),the others were SOM(10.8%)and POM(8.4%).6.There were significant differences between stable carbon isotope values of samples from different seasons(P<0.05),but there were no significant difference between ?15N values(P>0.05).Trophic structure of community-wide differed remarkably in the different seasons by 6 kinds of quantitative index results,the CR,TA,NND and SDNND were much higher in the summer of 2014 than those in the spring of 2015,but the NR and CD had no significant change,the trophic redundancy was lower in the summer than that in the spring,while the diversity of food resources were higher in the summer.