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

## TL;DR

This study shows that Chinese mitten crabs from Yangcheng Lake need at least six months of farming to develop stable isotopic fingerprints, which can help verify their authentic origin.

## Contribution

The study reveals that isotopic stabilization in mitten crabs occurs after six months, providing a scientific basis for geographical authentication.

## Key findings

- δ13C isotopic values stabilize after six months of cultivation.
- Crabs cultured for six months or longer have consistent isotopic fingerprints.
- Multivariate analysis shows overlapping isotopic data after six months, indicating stabilization.

## Abstract

This study investigated how the stable isotopic fingerprints of Yangcheng Lake mitten crab changes over a full year of farming. By analyzing δ13C, δ15N, δ2H and δ18O in the third pereiopod, researchers tracked these changes monthly. The key finding is that stable isotopic fingerprints of native Chinese mitten crabs need time to stabilize. While significant shifts occur in the first few months, the isotopes—particularly δ13C—become stable after six months of cultivation. After this point, the crabs’ stable isotopic fingerprints are consistent. This means that only crabs raised for at least six months in the Yangcheng Lake environment develop a true fingerprint of their origin. These findings are crucial for protecting the authentic Yangcheng Lake brand, as they provide a scientific basis to combat fraudulent products, thereby supporting the certification of premium aquatic goods.

The Chinese mitten crab (Eriocheir sinensis) 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 (δ13C, δ15N, δ2H and δ18O) 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 δ13C stabilized after six months of cultivation, showing no significant temporal variation (p > 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 δ15N and δ2H. 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.