Stable Isotope Composition of Fatty Acids in Organisms of Different Trophic Levels in the Yenisei River

Abstract

We studied four-link food chain, periphytic microalgae and water moss (producers), trichopteran larvae (consumers I), gammarids (omnivorous – consumers II) and Siberian grayling (consumers III) at a littoral site of the Yenisei River on the basis of three years monthly sampling. Analysis of bulk carbon stable isotopes and compound specific isotope analysis of fatty acids (FA) were done. As found, there was a gradual depletion in 13C contents of fatty acids, including essential FA upward the food chain. In all the trophic levels a parabolic dependence of δ13C values of fatty acids on their degree of unsaturation/chain length occurred, with 18:2n-6 and 18:3n-3 in its lowest point. The pattern in the δ13C differences between individual fatty acids was quite similar to that reported in literature for marine pelagic food webs. Hypotheses on isotope fractionation were suggested to explain the findings.

Stable isotopes as tracers of trophic interactions in marine mutualistic symbioses

“…Essential fatty acids (EFA), such as the "omega-6" and "omega-3" FA (linoleic acid, arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid), cannot be directly synthesized by animals and have to be acquired through predation or symbiont transfer; therefore, the δ 13 C-EFA values of the animal will be comparable to that of the symbionts or the external prey, since little or no isotopic fractionation occurs during this process (Treignier, Tolosa, Grover, Reynaud, & Ferrier-Pagès, 2009). In the case of non-essential FAs, which can be synthesized de novo by the animal, the δ 13 C values will reflect the competing processes of assimilation from external food and de novo synthesis (Gladyshev et al, 2012;Villinski, Hayes, Villinski, Brassell, & Raff, 2004). For the de novo synthesis of fatty acids, transferase and desaturase induce a δ 13 C isotope depletion in the synthesized fatty acid, while elongase provide a δ 13 C enrichment in the synthesized fatty acid (Figure 6).…”

“…In addition, while the method is quite sensitive, there are limitations for such sensitivity. However, for the de novo synthesis of fatty acids from pool of acetate in the animal tissue: Transferases/desaturases induce an isotope depletion in the synthesized fatty acid, while elongase adds carbon atom from the acetate pool and thereby provides the isotope enrichment in the synthesized fatty acid (modified from Gladyshev et al, 2012) F I G U R E 7 A schematic diagram of fractionation in individual amino acids nitrogen isotope value with trophic transfer. Isotopic fractionation may also be so minimal that little or no isotopic enrichment is detected.…”

Diet tracing in ecology: Method comparison and selection

“…Accurately estimating dietary use from a consumer's isotope ratio requires an accurate estimate of the TDF (Martínez del Rio et al., ). Trophic discrimination factors for a particular consumer–prey combination can be derived from laboratory studies (McCutchan et al., ), or approximated from simple trophic chains in the field (Gladyshev, Sushchik, Kalachova, & Makhutova, ). However, as trophic discrimination is influenced by temperature, growth rate, isotope routing, type of excretion and resource availability, TDF values derived from experimental settings may not reflect those of the natural environment (Martínez del Rio et al., ).…”

“…The analysis of δ 13 C ratios of specific fatty acids can distinguish between terrestrial and aquatic carbon resources (Gladyshev et al., ), including partitioning between different phytoplankton taxa (Taipale, Vuorio, et al., ). However, to date few studies have estimated dietary proportions, using δ 13 C isotope ratios of fatty acids, as the TDFs for individual fatty acids are unknown for most organisms.…”

Estimation of Amino Acid Quality of Food for Benthic Invertebrates and Fish on the Basis of Comparative Study of Amino Acids of Periphyton and Zoobenthos of the Yenisey River

“…Уровень насыщения растворенным кислородом около 100 %, со-держание органического углерода изменяет-ся от 7 до 10 мг/л. Детальная гидроэкологическая информа-ция о месте отбора проб собрана в работах (Sushchik et al, 2006;Kolmakov et al, 2008;Anishchenko et al, 2010;Kalachova et al, 2011;Gladyshev et al, 2012). (Kolmakov et al, 2008;Anishchenko et al, 2010;Sushchik et al, 2010).…”