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Fatty 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. [ABSTRACT FROM AUTHOR]

The article discusses research on the utilization of stable isotopes of body feathers to investigate seasonal isotopic niche changes of four southern procellariiformes and the level to which individuals are specialised relative to their population within each season. It states that niche variation has important implications for ecological interactions and conservation biology. It stresses that the study highlights the utility of feather isotopic signature of albatrosses for determining trophic niche width (TNW) and points out the necessity to develop such new approaches to better depict niche variations at both population and individual levels.

We investigated the relative importance of myctophid fish and Antarctic krill in the diet of adult flying seabirds of the Southern Ocean. The main prey of short-tailed shearwaters Puffinus tenuirostris (P. ten.), white-chinned petrels Procellaria aequinoctialis (P. aeq.), blue petrels Halobaena caerulea (H. cae.), thin-billed prions Pachyptila belcheri (P. bel.), and Antarctic prions Pachyptila desolata (P. des.) were mostly deduced from the lipid analysis of adult stomach oils. More than 97% of the 125 analyzed oils mainly consisted of wax esters (WEs) and triacylglycerols (TAGs) (>70% of total lipids). WE fatty alcohol (FAlc), WE fatty acid (FA), and TAG-FA profiles clearly segregated P. aeq. from P. ten., with smaller, but still significant, differences among the three other petrel species. P. aeq. and P. ten. therefore preyed on distinct prey species, whereas H. cae., P. bel., and P. des. had a more similar diet, but still with some prey differences. Comparisons between FAlc and FA patterns of oils with those of potential prey species showed that >93% of FAlc and FA patterns of oil WEs had a high probability of resemblance with the myctophid signatures, and similar results were obtained with the TAG fractions. Almost no stomach oil fit the lipid patterns of subantarctic and Antarctic euphausiids, including those of the WE-rich Thysanoessa macrura and the TAG-rich Antarctic krill Euphausia superba. This study thus demonstrates for the first time the importance of myctophids in the nutrition of adult flying seabirds breeding in subantarctic islands and foraging in Antarctic waters during the austral summer. [ABSTRACT FROM AUTHOR]