Demersal–pelagic relationships of aquatic animals in the East Siberian Sea based on (δ 15 N) and (δ 13 C) ratios and fish diets

Abstract

Stable nitrogen (δ15N) and carbon (δ13C) isotope ratios of zooplankton and zoobenthos were analyzed to compare the trophic characteristics of pelagic and demersal communities in the East Siberian Sea (ESS). The carbon isotope ratios of planktonic animals differed from those of benthic invertebrates; their δ13C ratios varied from -23.2 to -20.8 ‰, while those ratios varied from -21.8 to -17.0 ‰ in the zoobenthos. The relative boundary separating the pelagic and benthic communities corresponded to an average δ13C value of -20.5 ‰. The δ15N ratios of the studied species in the pelagic and benthic communities varied from 9.5 ‰ in comb yoldia Yoldia myalis to 18.7 ‰ in the sea star Urasterias lincki. There were significant differences in the δ15N ratios at the three trophic levels from filter feeders to predators. Trophic linkages in the ESS manifest a high degree of interdependence between the bottom and pelagic communities since both pelagic and bottom fish consume both benthic-derived and pelagic-derived food to some extent. The carbon isotope ratio of the snow crab Chionoecetes opilio in the northeastern ESS, δ13C = -17.0 ‰, is close to that of the opilio crab in the northern Chukchi Sea (δ13C = -17.3 ‰), which indicates that this species expanded westward from the Chukchi Sea.