MEPS 120:231-241 (1995)  -  doi:10.3354/meps120231

The contribution of different food sources in the food web of a shallow-water hydrothermal ecosystem was estimated using fatty acids as markers. The markers were selected based on the results of analyzing the fatty acid composition of potential food sources in Kraternaya Bight, Yankich Island, Kurile Islands. Most animals had markers characteristic of diatoms: the 16:0/16:1ω7 ratio close to 1 and a high 20:5ω3 content. We assume that the bivalves Macomacalcarea and Macomalukini, polychaetes Amphitritecirrata and Pectinariahyperborea, and holothurians Eupentacta pseudoquinquesemita and Psolus sp. feed mainly on diatoms. Fatty acids specific to bacteria - branched, odd and 18:1ω7 - were found in considerable amounts in the bivalve Axinopsidaorbiculata, as well as in E. pseudoquinquesemita, Psolus sp. and P. hyperborea; hence we concluded that there was a substantial bacterial input into the food of these species. A high concentration of C₁₈ and C₂₀ PUFAs (polyunsaturated fatty acids), suggested to be an indicator of brown algae, was detected merely in the gastropod Littorinakurila. Although bacteria are more important as a food source in Kraternaya Bight than in typical coastal ecosystems, the major food source for animals here is photosynthetic organisms, rather than chemosynthetic symbionts as is the case with deep-sea hydrothermal vents.

KEY WORDS: Vent · Food web · Fatty acid · Biomarkers