TITLE:    PALMER LTER: abundance and distribution of larval krill, Euphausia
PAGE:     96 of SCAR SIXTH BIOLOGY SYMPOSIUM, Antarctic Communities: Species,
          Structure and Survival 
          superba, associated with annual sea ice in winter
AUTHOR:   TK Frazer, LB Quetin, RM Ross, RC Smith
ABSTRACT: Larval krill, Euphausia superba, associated with annual sea ice were
censused visually using SCUBA during three winter cruises to a region west of
the Antarctic Peninsula.  Sampling on two cruises (September 1991, and June
1993) was restricted to a relatively small area offshore of Adelaide Island.
A larger, mesoscale survey (200km X 400km) was conducted in September 1993,
between Anvers Island and Margerite Bay.

Larval krill were observed feeding on ice-associated biota at all sampling
locations on each of the three cruises.  Larvae were concentrated under
complex habitat provided by over-rafted ice floes, and were generally
associated with upward facing ice surfaces.  Krill larvae were rarely observed
on the downward facing surfaces of individual floes that were not over-rafted,
though ice-algae was often visible in these areas, particularly in September
1993.  Larval abundance at any given sampling station was generally greater in
September than in June, irrespective of year.  The frequency of krill patches
and average patch size was also greatest during September sampling periods.
No significant difference in the mean abundance of krill larvae per transect
was observed between years.  However, data from the mesoscale survey of
September 1993, within the confines of the LTER grid, suggest that krill
larvae may be most abundant closer to shore.

Information on abundance and distribution of krill larvae and behavioral
observations are being coupled with physiological measures on the animals to
improve our understanding of the energetics of krill larvae in winter.