Trophic ecology of Penaeus chinensis (Decapoda: Dendrobranchiata: Penaeidae) and potential competitive interactions with other species in the Haizhou Bay determined by carbon and nitrogen stable isotope analysis

Abstract

The Chinese white shrimp Penaeus chinensis is one of the most economically important crustacean species in China with respects to both capture and aquaculture. Stable carbon and nitrogen isotope ratios (δ13C and δ15N) was analyzed to reveal its potential dietary characteristics, in particular contributions of primary producers as food sources, as well as isotopic niche width and potential food competitions with materials from Haizhou Bay in Yellow Sea, a state-level germplasm source conservation and stock recovery area. The results confirmed that bivalves served as an important diet of P.chinensis and the prawn incorporated a mixture of benthic microalgae and marine phytoplankton as food sources, while terrestrial organic matter supposed to be made minimum contributions. Benthic microalgae overwhelmingly dominated in the dietary proportion (mode), and accounted for 90% of the food sources in comparison with the contribution of 10% of marine phytoplankton. Penaeus chinensis was closest to Charybdis japonica and Dorippe japonica in isotopic compositions. Trophic niche widths were similar in P.chinensis and D. japonica, and they were larger than that of C.japonica, as determined by the sizes of SEAb (Bayesian standard ellipse areas). The overlaps of standard ellipse areas of P.chinensis with C. japonica and D. japonica were 98.5% and 86.5% respectively, indicating intense competition for food between P.chinensis and the other two species. In the views of food availability and competition, biomasses of benthic microalgae, bivalves and C.japonica and D.japonica may regulate the population of P.chinensis in Haizhou Bay.