Fatty acids as markers of food sources in a shallow-water hydrothermal ecosystem (Kraternaya Bight, Yankich Island, Kurile Islands)

Abstract

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 Right, Yankich Island, Kurile Islands.Most animals had markers characteristic of diatoms: the 16:0/16:1m?ratio close to 1 and a high 20:503 content.We assume that the bivalves Macoma calcared and Macoma lukini, polychaetes Amphitrite cirrata and Pectinaria hyperborea, and holothurians Eupentacta pseudoquinquesemita and Psolus sp.feed mainly on diatoms.Fatty a c ~d s specific to bacteriabranched, odd and 18:lw7 -were found in considerable amounts in the bivalve Ax~nopsida orbiculata, as well as in E pseudoquinquesernita, Psolus sp and P. hyperborea; hence we concluded that there was a substantial bacterial input into the food of these species.A high concentrat~on of C,, and PUFAs (polyunsaturated fatty acids), suggested to be an indicator of brown algae, was detected merely in the gastropod Littorina kurila.Although bactena 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 chernosynthetic symbionts as is the case with deep-sea hydrothermal vents.