BIOLOGIYA MORYA, 2018, Vol. 44, No. 1, pp. 51-57

Variations in the carbon and nitrogen isotopic composition of the crabs Chionoecetes opilio (Fabricius, 1788) and Hyas coarctatus Leach, 1816 (Crustacea: Decapoda) from the Chukchi Sea

© 2018 V. S. Odintsov, S. I. Kiyashko

A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041

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Some regions of the Chukchi Sea shelf are characterized by unusually high abundance of benthos. The carbon and nitrogen isotopic composition (δ¹³C and δ¹⁵N) of two crab species, Chionoecetes opilio and Hyas coarctatus, occupying the upper trophic levels in bottom communities in the southern regions influenced by the Anadyr Water (AW) and in the regions exposed to the influence of the Siberian Coastal Current (SCC), was analyzed in order to compare between the trophic characteristics of their benthic communities. It has been found that these two species have similar stable isotope signatures. As the effect of the productive AW on bottom communities decreases, a substantial depletion of δ¹³C with a simultaneous growth of δ¹⁵N values are observed in crab tissues. The trophic niches of C. opilio and H. coarctatus, represented by "isotopic" niches in the form of standard ellipse areas in the δ¹³C/δ¹⁵N biplot, significantly overlap in communities of the southern part of the shelf and become completely separated in those of the regions influenced by the SCC. The separation of the isotopic niches of C. opilio and H. coarctatus and the simultaneous increase in δ¹⁵N values in both species by more than 3‰ indicate partitioning of the trophic resources between them and elongation of the food chains of both these carnivorous generalists by almost one trophic level in the communities existing under the influence of less productive waters.

Key words: food chains, Chukchi Sea, benthos, communities, stable isotopes, trophic niches.