Seasonal differences of feeding ecology of Uroteuthis edulis in the East China Sea based on fatty acid and stable isotope.

Abstract

Uroteuthis edulis, an important fishery target species, plays an important role in the food web of the East China Sea. We collected U. edulis samples in the East China Sea from September 2020 to January 2021 to examine their feeding differences in autumn and winter based on fatty acid and stable isotope analyses. The results showed that the content of polyunsaturated fatty acids (PUFA) was the highest, followed by saturated fatty acids (SFA), and the lowest content of monounsaturated fatty acids (MUFA) in autumn and winter. Results of the similarity ana-lysis showed significant differences in PUFA and MUFA contents but no differences in SFA contents between autumn and winter. Results of non-metric multidimensional scale analysis showed that C18:1n9 could be used as signature fatty acids in autumn samples and C22:6n3 as characteristic fatty acids in winter samples. There was significant difference of δ15N between autumn and winter, but no difference of δ13C. The total area (TA), range of δ15N (NR), standard ellipse area (SEA) and the corrected version of the standard ellipse area (SEAC) in autumn were all smaller than those in winter, but range of δ13C (CR) was on the contrary. Results of the Spearman rank correlation test showed that there were differences between fatty acid content and stable isotope ratio of U. edulis and the dorsal mantle length in autumn and winter. Our results could provide basic data for understanding material and energy flow of the East China Sea food web, which is conducive to the sustainable development and utilization of U. edulis.