Fatty acid signature analysis documents the diet of five myctophid fish from the Southern Ocean

Abstract

International audienceFatty acid (FA) and fatty alcohol (FAlc) compositions of both total lipid and neutral lipid fractions were studied for five myctophid species sampled in Kerguelen waters. Both qualitative and quantitative FA signature analyses were then performed to investigate their diet over longer time scales than the conventional stomach content analysis. Regarding their lipid class, FA and FAlc compositions, the five species could be discriminated into two groups: wax-ester-rich species (Electrona antarctica, Krefftichthys anderssoni) characterised by large amounts of monounsaturated FAs ([73% of total FAs) and triacylglycerol- rich species (Electrona carlsbergi, Gymnoscopelus nicholsi, Protomyctophum bolini) with major amounts of saturated and monounsaturated FAs ([29 and[46% of total FAs, respectively). Qualitative and quantitative FA analyses showed that K. anderssoni mainly preyed upon copepods, E. antarctica upon copepods and more euphausiids and P. bolini and E. carlsbergi mainly upon euphausiids with some copepods, while G. nicholsi had a more diverse diet. This study shows the usefulness of quantitative statistical analysis to determine the diet of Antarctic and sub-Antarctic predators and stresses the need of increasing the lipid and FA analyses of more zooplanktonic and micro-nektonic marine species

Proximate composition and energy density of nototheniid and myctophid fish in McMurdo Sound and the Ross Sea, Antarctica

“…Other myctophid species in the Southern Ocean also have high fat and energy contents, with the possible exception of Protomyctophium spp. that contain 4-10% WM fat and 4-7 kJ g ¡1 (Donnelly et al 1990;Lea et al 2002b;Tierney et al 2002;Connan et al 2010). In general, myctophids are lipid-and energy-rich prey, due to accumulation of triacylglycerols (e.g., E. carlsbergi, G. nicholsi) or wax esters (e.g., E. antarcticus, G. braueri) (Phleger et al 1997(Phleger et al , 1999Connan et al 2010).…”

“…Published data are available on the water, lipid and/or energy contents of the four myctophids of the genera Electrona and Gymnoscopelus at other locations: Bird Island (Clarke and Prince 1980), Croker Passage (Reinhardt and Van Vleet 1986), Kerguelen Plateau (Lea et al 2002b;Connan et al 2010), Macquarie Ridge (Lea et al 2002b;Tierney et al 2002), the Lazarev Sea ( Van de Putte et al 2006) and the Cosmonaut Sea ( Van de Putte et al 2010). These studies agree with our Wndings (for Wsh of similar size class) in that these myctophids are high in fat (12-19% vs. 8-17% WM in our study) and energy (7-13 kJ g ¡1 vs. 6-10 kJ g ¡1 WM), although Tierney et al (2002) reported a somewhat lower energy density (5.4 kJ g ¡1 ) for E. carlsbergi at Macquarie Ridge.…”

“…that contain 4-10% WM fat and 4-7 kJ g ¡1 (Donnelly et al 1990;Lea et al 2002b;Tierney et al 2002;Connan et al 2010). In general, myctophids are lipid-and energy-rich prey, due to accumulation of triacylglycerols (e.g., E. carlsbergi, G. nicholsi) or wax esters (e.g., E. antarcticus, G. braueri) (Phleger et al 1997(Phleger et al , 1999Connan et al 2010). It is not known if myctophid species high in wax esters are more diYcult to digest (Place 1992), although some seabirds and whales appear to have compensatory mechanisms to allow wax ester utilization (Place 1992;Nordoy 1995).…”

Lipid and Fatty Acids of Three Edible Myctophids, Diaphus watasei, Diaphus suborbitalis, and Benthosema pterotum: High Levels of Icosapentaenoic and Docosahexaenoic Acids

“…In polar lipids, medium levels of phospholipids, which are probably important as tissue membrane lipids, were observed in both deep-sea and surface fish species. High levels of TAG in the three edible myctophids, D. watasei, D. suborbitalis, and B. pterotum, show a typical lipid profile of a diel migratory myctophid, similar to those in other species 5,7,16,18,23 .…”

Combined stomach content, lipid and stable isotope analyses reveal spatial and trophic partitioning among three sympatric albatrosses from the Southern Ocean

“…Non-metric multidimensional scaling was used to visualize differences between species; relationships between samples were considered well represented when stress was < 0.2. An attempt at identifying the prey from which triacylglycerols in oils originated was then made using a quantitative analysis (Iverson et al 2004; see details in Connan et al 2010a). Briefly, the proportional contribution of a prey species to the oil composition was determined by taking a weighted mixture of the fatty acid signatures of potential prey species and then choosing weighting that minimised the statistical distance from that of albatrosses (Iverson et al 2004).…”