Fatty acid profiles of deep-sea fishes from the Lucky Strike and Menez Gwen hydrothermal vent fields (Mid-Atlantic ridge)
At least 40 fish species have been observed in the Lucky Strike and Menez Gwen hydrothermal vent fields and surrounding areas. The endemic vent fauna has been recorded as a food source for several fish species, thus establishing a link between the chemosynthetically driven environment and the surrounding bathyal area. Biomarkers, such as fatty acids can be used to understand trophic relationships, complementing more traditional approaches such as stomach content analyses. Therefore a diet based on hydrothermal vent organisms is likely to affect, at least to some extent, the fatty acid composition of a fish. The present paper focuses on the fatty acid composition of fish species captured with long lines at the Lucky Strike (37º17’N, 32º16’W; 1560-1760m) and Menez Gwen (37º50’N, 31º30’W; 788-970m) hydrothermal vent fields and in a non-hydrothermal intermediate point (37º44’N, 32º05’W; 890-960 m). Samples of muscle, liver and gonad were taken from 11 fish species. For each species fatty acid analyses allowed the characterization of the different tissues, revealing differences between species and also within species. The main fatty acids were the SFA C16:0, C18:0, the MUFA C16:1n-7, C18:1n9, C20:1n-9 and the PUFA C16:4n-3, C20:4n-6, C20:5n-3, C22:5n-3 and C22:6n-3.The fatty acid composition is discussed for each species in terms of ecological and biological significance. An attempt was made to determine the possible relationship between the studied species and the hydrothermal environment and to evaluate to which extent these species were dependent on the vent fauna as a food resource.