Identifying trophic relationships within the high Arctic benthic community: how much can fatty acids tell?

• Published in: Marine biology Vol. 161; no. 4; pp. 821 - 836
• Main Authors: Legeżyńska, Joanna, Kędra, Monika, Walkusz, Wojciech
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2014; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Bacillariophyceae; Biological and medical sciences; Biomedical and Life Sciences; Calanus; Fatty acids; Food and nutrition; Food chains; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; Invertebrate populations; Life Sciences; Marine; Marine & Freshwater Sciences; Marine biology; Microbiology; Mollusca; Oceanography; Original Paper; Predation; Sea water ecosystems; Synecology; Trophic levels; Unsaturated fatty acids; Zoology; Arctic Region; Arctic Ocean; Norway, Svalbard, Spitsbergen; PN, Arctic; Polychaete; Total Fatty Acid; Fatty Acid Profile; Stable Isotope Analysis; Fatty Acid Composition; Lipids; Trophic relation; Benthic organism; Polar region; Biocenosis; Fatty acids
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-013-2380-8

Multivariate analysis of fatty acids (FA) profiles proved to be a useful tool for demonstrating feeding preferences of Arctic invertebrates belonging to several taxonomic groups collected during summer and winter seasons in the Spitsbergen fjords (Arctic). Within phytodetrivorous taxa, the enhanced proportions of 16:1n-7, C16 polyunsaturated fatty acids (PUFA) and 20:5n-3 in crustaceans clearly reflected selective ingestion of diatoms, while high amounts of 22:6n-3 and C18 FAs found in molluscs indicated flagellate-based nutrition. High levels of C20 PUFA and 16:1n-7 together with the typical bacterial FAs were found in winter specimens of deposit-feeding polychaetes showing their reliance on highly reworked organic matter during this season. Our results suggest that 18:1n-9 may not be a reliable marker of carnivory feeding within benthic taxa. Lipid signatures of omnivores and carnivores/detrivores usually originated from a variety of dietary sources, of which few possess highly characteristic FA features. Still, elevated levels of Calanus markers (20:1 and 22:1 moieties) characterized species linked to the pelagic food chains, while 20:4n-6 proved to be a useful indicator of foraminiferan consumption. We highlight the need for a multimethod approach, since complexity of benthic food webs along with general lack of unambiguous FA trophic markers prevents tracking of trophic relationships with use of FA analysis alone. Based on their FA composition, we showed that benthic species represent a source of essential PUFA and could play a fundamental role in the Arctic food webs transferring energy derived from variable pelagic and benthic resources to upper trophic levels.