[Analysis of food sources of in rice-crab integrated ecosystem based on stable isotopes in saline-alkali land of the Yellow River Delta].

To explore food composition of Chinese mitten crab () in rice-crab integrated ecosystem in saline-alkali land of the Yellow River Delta, we analyzed carbon and nitrogen stable isotope ratios (δC and δN) in the crab and that in food sources, including plants (, , , , stem and leaf, rice grain), animals (benthos, zooplankton), organic debris and artificial feed (compound feed, corn meal) in Kenli District, Dongying, Shandong Province in June to October of 2020. Substantial differences in δC and δN were found among food sources. The δC and δN values of different food sources were in a range of -30.09‰--11.24‰ and 0.03‰-12.78‰, respectively, while those of the crab muscle were in range of -24.61‰--20.08‰ and 4.74‰-9.21‰, respectively, indicating diverse food sources for the crab. During the experiment, the contribution rate of different food sources followed the order: plant (46.7%-57.1%)>animal (21.5%-24.5%)>artificial feed (10.9%-21.3%)>organic detritus (7.1%-7.9%). It suggested that the natural bait of the paddy field could meet the feeding needs of Chinese mitten crabs in saline-alkali land. Even the crabs were fed with non-animal artificial feed, the contribution rates of the main food sources were not altered.