Environmental conditions and adaptive features of the biology of Euphausia superba dana in the Lazarev Sea

Abstract

Extensive sampling of krill (Euphausia superba Dana) was carried out from the polar research vessel Akademik Knipovich in the Lazarev Sea in March 1981. Analysis of the results revealed some very interesting patterns in the distribution and age structure of the population of these crustaceans. The highest concentrations of E. superba were found in the extreme south near the Antarctic coast, in the waters of the Antarctic Coastal Current; a secondary, minor concentration was found farther north in the waters of the Weddell Drift. Larvae concentrations revealed the same pattern. Most interestingly, the size of larvae and the state of the females revealed that E. superba spawns earlier in the south than in the north of the Lazarev Sea. The authors hypothesize that the control may be the occurrence of a plankton “oasis,”; i.e., an area of particularly abundant phytoplankton, in the south of the Lazarev Sea, linked to an area of abnormally fresh water associated with ice retreat and with quasi‐stationary gyrals on the margins of the Antarctic Coastal Current.