Diet shift of Chinese mitten crab (Eriocheir sinensis) during its upstream migration indicated by stable isotopes and fatty acid composition

ABSTRACT

The Chinese mitten crab (Eriocheir sinensis) is the largest estuarine invertebrate and one of the most important fishery resources in China. Diet significantly affected survival of the crab. To study the diet of this species during its upstream migration, larvae and juvenile crabs as well as their potential food sources were sampled from three regions along the Changjiang River. Stable isotopes (δ¹³C and δ¹⁵N) in and fatty acid compositions of the samples were analysed to elucidate the crabs’ dietary shift during upstream migration. With upstream migration from the Changjiang Estuary, the average δ¹³C value in crabs decreased from −20.6 to −25.2‰, and the δ¹⁵N value increased from 3.0 to 11.8‰. The fatty acid compositions also changed significantly, with levels of C20:4n-6, C18:2n-6, and C18:3n-3 increasing during upstream migration. However, the levels of C15:0, C17:0, C16:1n-7, and 20:1n-9 exhibited the opposite trend. Pelagic marine prey items (e.g. zooplankton and bacteria) were the dominant food sources of megalopae and early juvenile crabs. The contribution of benthic terrigenous origin carbon sources (e.g. macrophytes and zoobenthos) to the juvenile crab diet sharply increased. The dietary information on the Chinese mitten crab can promote the restoration of wild population and sustainable development of crab aquaculture.

KEYWORDS:

• Eriocheir sinensis
• stable isotopes
• fatty acids
• diet source
• upstream migration

Acknowledgments

We thank G.H. Ji for identifying the zooplankton samples and gut content of the crab. We are grateful to F. Zhao, G. Yang and Z. Geng for helping us to collect the samples. This work was supported by the Young Scientists Fund of the National Natural Science Foundation of China (41706128), the National Key Research and Development Program of China (2016YFA0600902), the ‘Shu Guang’ project (17SG46) from Shanghai Education Commission and Shanghai Education Development Foundation, and the Special Fund (CARS-48) of Chinese Agriculture Research System from Ministry of Agriculture of China.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Young Scientists Fund of the National Natural Science Foundation of China (41706128), the National Key Research and Development Program of China (2016YFA0600902), the ‘Shu Guang’ project (17SG46) from Shanghai Education Commission and Shanghai Education Development Foundation, and the Special Fund (CARS-48) of Chinese Agriculture Research System from Ministry of Agriculture of China.