Trophic relationship of benthic invertebrate fauna from the continental slope of the Sea of Japan

The Sea of Japan continental slope food web was examined by analysis of stable C and N isotopes and fatty acid compositions in ten species of common benthic organisms and in sediment and particulate organic matter. A considerable range of δ13C and δ15N values was found for benthic species, with δ13C values of −22.3‰ in crinoids (Heliometra glacialis) to −16.1‰ in asteroids (Ctenodiscus crispatus) and with δ15N values of 5.3‰ in foraminifera (Elphidium sp.) to 15.5‰ in C. crispatus. Polyunsaturated fatty acids were the most abundant of the fatty acids in the total lipids of all investigated species. The organisms’ individual fatty acid compositions show the importance of a variety of food sources, including phytoplankton, detritus, foraminiferans and zooplankton, for megabenthic species. Additionally, the presence of considerable amounts of the 20:4(n-6) and 20:1(n-13) fatty acids indicates the importance of the benthic microbial loop in the nutrition of some of the studied animals.