TITLE:     Interannual variation in recruitment processes in Antarctic krill
           in relation to seasonal sea ice dynamics
AUTHOR:    RM Ross, LB Quetin (not presented at ASLO but gordon conf.)
DATE:      10-14 February 1997 
PLACE:     ASLO, Aquatic Sciences Meeting, Santa Fe, New Mexico
           Talk
ABSTRACT:  
Recruitment success in a specific region is affected by both reproductive
output of the population during a spawning season and survival of the larvae
produced.  Four years of sequential annual sampling within the regional grid
of the Palmer LTER (Long-Term Ecological Research) allows us to examine
interannual variability both in recruitment sucess (at the end of the first
year of life), and in individual reproductive output and reproductive stock.
The recruitment index ranged from a high of 88% to a low of 0.2%.
Reproductive stock varied by a factor of 30, but individual reproductive
volume only varied by a factor of 2.  Different phases of the seasonal changes
in sea ice (Smith et al., submitted) appear to influence the recruitment
index, and individual reproductive volume.  The recruitment index was
correlated with dynamics of winter ice area (actual coverage), and increased
with increasing months of above average area and an early advance.  However, an
early retreat to summer conditions could negate both these factors.  For
spawning females, an increasing amount of austral spring ice extent (outer
edge of ice pack) was associated with both an increase in embryo size and in
total individual reproductive output.  Thus multiple aspects of seasonal sea
ice dynamics influence the proceses of recruitment and reproduction in
Antarctic krill.