Lipid composition of stomach oil in a procellariiform seabird Puffinus tenuirostris: implications for food web studies

Abstract

Some procellariiform seabirds use a dual strategy for provisioning their chicks by alternating between short and long foraging trips (LT). Trophic relationships of adult birds are unknown when they feed for themselves during LT because digestion processes preclude direct prey determination. Since stomach contents collected after LT contain oil of dietary origin, we tested the use of oil lipids as prey trophic markers using the Tasmanian short-tailed shearwater Puffinus tenuirostris as a model seabird. The intra-specific variability of stomach oils was investigated through lipid class composition, and their fatty acid and fatty alcohol profiles. Oils mainly consisted of wax esters (WE) and triacylglycerols (TAG) (49 to 86 and 7 to 41%, respectively). Major fatty acids of TAG were in a decreasing order 18:1n-9, 16:0, 16:1n-7, 14:0, 20:5n-3 and 22:6n-3. The WE-fatty acid profiles were dominated by 18:1n-9 and 16:1n-7 while fatty alcohol profiles were dominated by 16:0. Fatty alcohol and fatty acid patterns were tested as possible descriptors of ingested prey (derived from literature data) through multivariate discriminant analyses. Comparisons of the WE fatty alcohol patterns showed a close association with the alcohol structure of 3 myctophid fish species namely Krefftichthys anderssoni, Gymnoscopelus braueri and Electrona antarctica; these results were corroborated by WE fatty acid analysis. Comparison of TAG fatty acid patterns showed the highest similarity between oils and the digestive gland of the myctophid-eater squid Moroteuthis ingens in association with the myctophid Electrona carlsbergi. Hence, biochemical analysis of both WE and TAG strongly suggested that adult short-tailed shearwaters mainly prey upon Antarctic/subAntarctic myctophids when they feed for themselves, thus emphasizing the role of these oceanic mesopelagic fish in the marine ecosystem of the Southern Ocean.

Interannual dietary changes and demographic consequences in breeding blue petrels from Kerguelen Islands

“…Crude extracts were placed in chloroform, concentrated under vacuum and stored at -80°C. All samples were then analyzed using the methods described by Connan et al (2005). Briefly, the proportions of lipid classes were determined with an Iatroscan MKV TH10 thin-layer chromatography- Conventional dietary approach.…”

“…To achieve meaningful comparisons between FAlc and FA patterns from potential prey species and stomach oils, 3 databases were built using the majority of published studies on subtropical, subantarctic and Antarctic potential prey (databases available on request from M. Connan). They included the main species of meso-and macrozooplankton, micronekton and nekton of the Southern Ocean (details in Connan et al 2005), plus the nototheniid Dissostichus eleginoides (Wilson 2004), and the myctophids Electrona antarctica, E. carlsbergi, Gymnoscopelus nicholsi, Krefftichthys anderssoni and Protomyctophum bolini, (authors' unpubl. data).…”

“…This, together with a much slower passage rate of lipid than aqueous digesta in the stomach (Clarke 1989) indicates that oil reflects the diet of adult birds before they collect food for their chicks. Consequently, the biochemical composition of oil was recently tested and used as an efficient tool to investigate the food of adult procellariiform seabirds when they feed for themselves (Connan et al 2005(Connan et al , 2007a.…”

Carbon isotopic fractionation in eider adipose tissue varies with fatty acid structure: implications for trophic studies

“…New techniques using minimally invasive sampling methods and biochemical signatures in stored fat Wang et al, 2010), blood (Käkelä et al, 2009;Federer et al, 2010), stomach oil (Connan et al, 2005;Wang et al, 2007), feathers (Hobson and Clark, 1992) or eggs (Hobson, 1995;DeVink et al, 2011) provide promising alternatives for diet assessments in avian populations. These biomarker techniques typically involve either stable isotope or fatty acid (FA) analysis.…”

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

“…identification of prey remains) provides information about the most recent meals of an individual. Procellariiform species are unique in that most of them are able to store oil of dietary origin in their proventriculus (Warham et al 1976) and the fatty acid signatures of these stomach oils provide dietary information about the last foraging trip (Connan et al 2005(Connan et al , 2007. Carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope ratios have been used as indicators of foraging areas and trophic level, respectively (e.g.…”