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Occurrence of 16:2(n-4) and 18:2(n-4) fatty acids in the lipids of the hydrothermal vent shrimps Rimicaris exoculata and Alvinocaris markensis: nutritional and trophic implications

Pond, D.W., Dixon, D.R., Bell, M.V., Fallick, A.E., and Sargent, J.R. (1997) Occurrence of 16:2(n-4) and 18:2(n-4) fatty acids in the lipids of the hydrothermal vent shrimps Rimicaris exoculata and Alvinocaris markensis: nutritional and trophic implications. Marine Ecology Progress Series, 156 . pp. 167-174. ISSN 0171-8630

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Publisher's URL: http://www.int-res.com/abstracts/meps/v156/p167-174/

Abstract

Adults of 2 species of vent shrimp, Rimicaris exoculata and Alvinocaris markensis, were sampled from the Snake Pit and TAG hydrothermal vent sites on the mid-Atlantic ridge. Fatty acid analyses indicated high abundances of 16:2(n-4) and 18:2(n-4) in the lipids of R. exoculata, with the highest proportions of these fatty acids detected in the digestive gland [14.5% 16:2(n-4) and 23.8% 18:2(n-4)]. Lipid extracted from abdominal muscle of R. exoculata also contained these fatty acids, although in lower proportions [2.0% 16:2(n-4) and 14.5% 18:2(n-4)]. By contrast, lipid extracted from the same tissues in A. markensis contained relatively low proportions of (n-4) fatty acids (1.9 to 3.0%), but was substantially enriched in the phototrophic, microplanktonic biomarkers 20:5(n-3) and 22:6(n-3). GC-IRMS (gas chromatography with isotope ratio mass spectrometry) analysis of the (n-4) dienoic fatty acids established delta13C values of -11.0 to -11.4o/oo which is consistent with the fatty acids being derived from chemosynthetically fixed carbon. By contrast, those fatty acids which are characteristic of phototrophic microplankton were isotopically lighter, i.e. -17.1, -17.3 and -15.8o/oo for 20:4(n-6), 20:5(n-3) and 22:6(n-3) respectively. The non-methylene interrupted dienes (NMIDs) 20:2Delta5,13 and 22:2Delta7,15 were detected in all samples although in small amounts with R. exoculata containing the highest amounts. The (n-4) dienes and NMIDs are consistent with a substantial dietary input of bacterially derived 16:1(n-7) and 18:1(n-7) fatty acids for this species. Thus, these results are consistent with R. exoculata adopting a bacterivorous mode of nutrition whilst A. markensis is essentially a scavenger (necrophagous) and suggest that the 2 species are not in direct competition for their food supply.

Item Type:Article
Keywords:Hydrothermal vent shrimp, fatty acids, nutrition, trophic ecology, stable carbon isotope, DELTA12 desaturase, (n-4) PUFA
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Fallick, Prof Anthony
Authors: Pond, D.W., Dixon, D.R., Bell, M.V., Fallick, A.E., and Sargent, J.R.
Subjects:Q Science > QH Natural history > QH301 Biology
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Marine Ecology Progress Series
ISSN:0171-8630
ISSN (Online):1616-1599

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