Nitrogen and carbon isotopic compositions in Euphausia superba Dana collected off the Ongul islands in Lützow-Holm Bay, near Syowa Station, Antarctica in 1984-85

Abstract

This paper is a part of the report on the Marine Biological Research Activities of the 25th Wintering Expedition of the JARE (Japanese Antarctic Research Expedition) in 1984-85, focusing on the feeding behavior of Antarctic krill, Euphausia superba Dana, under the land fast ice near Syowa Station. Nitrogen and carbon isotopic compositions of individual E. superba showed wide seasonal variability and was clearly demonstrated that a Two Source Model can be applied to explain the feeding habits, and indicated the krill fed on both phytoplankton and ice algal productions at the benthopelagic layer with showing seasonal difference under the fast ice-covered condition. The δ15N and δ13C values of algae ingested by the end member krill were estimated using trophic discrimination factors (TDF) and compared with those of pelagic phytoplankton on the δ15N-δ13C map to clarify the isotopic characteristics of the research site.

Keywords

• sea ice ecosystem
• ongul island
• ice krill
• δ15n-δ13c
• food habits under ice
• antarctic sea