Stomach content analysis and feeding habit of the Antarctic krill <italic>Euphausia superba</italic>: A review

Abstract

Antarctic krill (<italic>Euphausia superba</italic>) has become a key species in the Antarctic ecosystem due to its abundant biomass and important position in the food web; therefore, its ecological role and feeding activities have garnered increasing attention. Antarctic krill is a typical phytophagous zooplankton, but also exhibits a certain degree of omnivorous behavior, as its feeding composition differs owing to the varying dominance of phytoplankton in the sea, thus having the potential to be a natural sampler of phytoplankton. The study of stomach content analysis has a long history, but those studies have significant spatiotemporal differences and the study areas were sparse and uneven with regard to circumpolarly. With the application of emerging approaches in the study of feeding habits, stomach content analysis has lacked necessary attention in recent years, due to being time-consuming, labor-intensive, and requiring a high-level of professional knowledge. However, as a direct way to examine the short-term feeding activity of Antarctic krill, the limitation of this single approach could be overcome by combining the traditional method, i.e. stomach content analysis, with lipid biomarker analysis, stable isotope analysis, PCR, and other emerging methods. Such practice will provide more accurate and comprehensive data on the feeding ecology of Antarctic krill for future studies. This paper summarized and concluded the research status of the stomach contents of krill, methods and applications, major gastric species, and seasonal, sea area, and ontogenetic differences, and further explored the potential of stomach content analysis of krill as a natural sampler of phytoplankton in the Southern Ocean. The results provide new scientific ideas for further study of the trophic dynamics of the Antarctic marine ecosystem.