Analysis of Annual Variation in Stable Isotopic Fingerprints of Native Chinese Mitten Crab (Eriocheir sinensis) from Yangcheng Lake

The Chinese mitten crab (<i>Eriocheir sinensis</i>) from Yangcheng Lake is a globally renowned geographical indication product. To characterize changes in stable isotopic signatures in this species in Yangcheng Lake during the year-round culture period, this study investigated the dynamic changes in stable isotopic fingerprints (<i>δ</i>¹³C, <i>δ</i>¹⁵N, <i>δ</i>²H and <i>δ</i>¹⁸O) of the third pereiopod across an annual aquaculture cycle. Isotopic ratios were analyzed via one-way ANOVA, principal component analysis (PCA), linear discriminant analysis (LDA) and Pearson correlation analysis. Results demonstrated that <i>δ</i>¹³C stabilized after six months of cultivation, showing no significant temporal variation (<i>p</i> > 0.05). Multivariate statistical analysis further revealed that the samples cultured in the initial period could be clearly differentiated in both PCA and LDA plots. However, after six months, the monthly sample points became highly overlapping and indistinguishable, indicating that the crabs had developed stable and consistent isotopic "fingerprints" by that time. Pearson correlation analysis indicated significant correlations among all other isotope pairs, with the exception of <i>δ</i>¹⁵N and <i>δ</i>²H. This study confirms that isotopic signatures require prolonged cultivation (≥6 months) to reflect authentic geographical traits. In addition, our findings provide a basis for verifying the origin of Chinese mitten crab and other aquatic taxa in Yangcheng Lake.