BIOLOGIYA MORYA, 2015, Vol. 41, No. 6, pp. 418-424

Fatty acid composition and nutrition of deep-sea holothurians from the Sea of Okhotsk

© 2015 V. I. Kharlamenko¹, V. G. Stepanov², E. E. Borisovets^3,4, S. I. Kiyashko^1,3, V. I. Svetashev¹

¹A.V. Zhirmunsky Institute of Marine Biology, Far East Branch, Russian Academy of Sciences, Vladivostok 690041;
²Kamchatka Branch of Pacific Geographical Institute, Far East Branch, Russian Academy of Sciences, Petropavlovsk-Kamchatsky 683000;
³¹Far Eastern Federal University, Vladivostok 690950;
⁴Pacific Fisheries Research Centre, Vladivostok 690950

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Results of a comparative study of the fatty acid composition in eight species of sea cucumbers collected in the Sea of Okhotsk in the area of the Kuril Islands (depths of 90-560 m) are presented. It is shown that interspecific differences in the fatty acid compositions of the sea cucumbers were consistent with the isotopic composition (δ¹³C and δ¹⁵N) and the structural features of the tentacles and the lifestyle of holothurians, as indicators of trophic resources used by these holothurians. According to results of the cluster analysis, the holothurians were divided into three groups. The first group included suspension-feeding dendrochirotides Eupentacta pusilla and Pseudocnus fallax with a high content of fatty acid 20:5(n-3), a marker of diatoms, and with the values of δ¹⁵N, typical of consumers of suspended organic matter. The second group consisted of dendrochirotides Psolus chitonoides and Psolidium sp. with a much lower content of 20:5(n-3) and higher contents of 20:4 (n-6) and 22:6(n-3), as well as high values of δ¹⁵N, typical of surface deposit-feeders. The third group consisted of surface and subsurface deposit-feeders, Chiridota sp., Molpadia orientalis, Pseudostichopus mollis, and Synallactes nozawai. Typical of the third group were very high contents of 20:4(n-6) and 21:4(n-7) and the highest values of δ¹⁵N, indicating feeding on repeatedly recycled organic matter.

Key words: holothurians, the Sea of Okhotsk, fatty acids, stable isotopes, trophic relationships.