Comparative Analysis of the Fatty Acid Profiles of Antarctic Krill (Euphausia superba Dana, 1850) in the Atlantic Sector of the Southern Ocean: Certain Fatty Acids Reflect the Oceanographic and Trophic Conditions of the Habitat

The present study is the attempt to combine oceanologic measurements and biochemical analysis, which is as possible to implement on board as in a laboratory with chosen certain statistics to reveal trophic conditions and the environment state in which Antarctic krill live in season in real time on site. The fatty acid constituents of total lipids in juvenile and mature Antarctic krill sampled from the Bransfield Strait (BS), the Antarctic Sound (AS), and waters at the eastern tip of the Antarctic Peninsula (AP) collected during the 87th cruise of the R/V Akademik Mstislav Keldysh in January-February 2022 were analyzed. The fatty acid (FA) profile in juvenile and mature Antarctic krill was studied by gas chromatography with a mass selective detector to identify the qualitative composition and a flame ionization detector to quantify the studied FAs. Using NMDS analysis (quantitative panel), great difference was found between krill from the BS compared to krill collected in the AS and the AP. The differences are reliable owing to the following 16 FAs, most of them trophic biomarkers of microphytoplankton, and suggest regional differences, mainly in abundance and ability of forage objects. CTD measurements discuss the abiotic factors (potential temperature, salinity, and chlorophyll a). Compensatory modifications of the composition of FA components in Antarctic krill inhabiting different water areas are a way of maintaining the species' viability under certain and variable habitat conditions.

Automated summary

The present study aims to combine oceanologic measurements and biochemical analysis to reveal the trophic conditions and environment state of Antarctic krill in real time. By analyzing the fatty acid composition of Antarctic krill samples collected from different water areas, significant differences were found, indicating regional variations in abundance and foraging ability. Additionally, the study discussed the impact of abiotic factors using CTD measurements. The results suggest that Antarctic krill undergo compensatory modifications in the composition of fatty acid components to adapt to different habitat conditions.