Winter abundance and distribution of Euphausia superba, E. crystallorophias, and Thysanoessa macrura in Gerlache Strait and Crystal Sound, Antarctica

Euphausia superba and Thysanoessa macrura were the 2 most abundant euphausiids in the ice-covered waters west of the Antarctic Peninsula during July and August 1992.E. crystallorophias was limited to inshore waters.Detailed stratlfled sampling revealed that E. superba formed dense aggregations well below the ice, but was not inhabiting the ice itself In general, E. superba occupied the depth stratum from 15 to 130 m; few or no other zooplankton were found within E. superba swarms.7: rnacrura displayed a depth preference for the strata from 90 to 250 m.Size-frequency distributions for E. superba and for 7: rnacrura showed that larvae were absent and that both populations were dominated by small adults.A life cycle for 7: macrura is proposed.