Trophic structure of fishery organism assemblage in Daya Bay based on carbon and nitrogen stable isotope analysis

According to the biological survey of bottom trawl fishery conducted in Daya Bay in the summer of 2017 and the winter of 2018, we analyzed the basic characteristics of the stable isotope of carbon and nitrogen (δ¹³C and δ¹⁵N) in fishery organisms by using δ¹³C and δ¹⁵N techniques. In addition, we constructed a continuous trophic level spectrum, and discussed the differences in the nutritional structure of fishery organisms in different seasons. The results show that the range of (δ¹³C and δ¹⁵N) of main fishery species in Daya Bay were −19.66‰−15.19‰ Average: (−17.26±0.86)‰ and 11.63‰−16.01‰ Average: (13.59±0.96)‰, respectively. We used the average δ¹⁵N of small zooplankton as a reference to construct the trophic level spectrum of fishery organisms, and found that the trophic level of fishery organisms in Daya Bay ranged from 2.99 to 4.28. The trophic level of fish had the widest span and a more complex diet. We calculated seven quantitative community indices of trophic structure of macrobenthos by using the SIBER model, and found that some organisms shared the preys, and there was a phenomenon of niche overlap. In addition, the community nutrition redundancy in summer was lower than that in winter.