Ontogenis changes in the feeding ecology of the early life stages of the Antarctic silverfish (Pleuragramma antarcticum) documented by stable isotopes and diet analysis in the Dumont d'Urville Sea (East Antarctica)

International audienceThe feeding ecology of the notothenioid fish Pleuragramma antarcticum was studied in the Dumont d'Urville Sea (East Antarctica) near the French Antarctic station. Stable isotopes (d13C and d15N) and diet contents were used in order to study dietary shifts between fish larvae and juveniles. All specimens had low d13C values (< 24&), a main characteristic of high-Antarctic pelagic species. Fish larvae showed differences in both carbon and nitrogen ratios when compared with juveniles. Muscle d15N values showed a difference of one trophic level (w3&) between larvae (6.7&) and juveniles (9.7e10.0&) and a trophic position of tertiary consumers. Diet content analyses (stereomicroscope and scanning electron microscopes) indicated that larvae are omnivorous, feeding on phytoplankton (mainly diatoms) as well as on zooplankton species. A positive relationship between d15N values and size was found and indicated a carnivorous diet for older specimens