TITLE:   Growth of larval euphausia superba in the pack ice habitat:
         interannual and seasonal variability
AUTHORS: Stephanie Oakes, Langdon Quetin, and Robin Ross
DATE:    2-4 August 2000
PLACE:   LTER All Scientists Meeting 2000, Long-Term Ecological Research:
	 Unifying Principles & Global Applications, Snowbird, Utah
         
	 University of California, Santa Barbara, CA 93106
	 Poster - Session: Population Studies/Biodiversity (W67)

ABSTRACT

Antarctic krill is the key herbivore in the pelagic ecosystem west of the
Antarctic Peninsula.  Physiological and behavioral evidence suggest that
larval krill survive and grow during the prolonged period of low food 
availability in the water column during the austral winter by feeding on pack 
ice-associated biota.  To investigate the temporal nature of growth in larval 
krill in the pack ice habitat we test the hypothesis that growth is constant 
when larvae are feeding on ice biota.  Growth parameters (increment per
intermolt period and intermolt period) were determined from short-term in
situ  experiments on a series of 9 fall and winter cruises between 1987 and
1999, 3 for the Palmer LTER.  The seasonal difference in growth parameters was
larger than the interannual variability.  The % growth per intermolt period 
increased from ~2% in June to ~10% in September.  The intermolt period was 
steady at 3.5 to 4 weeks throughout the time period.  The combined results 
indicate a significant increase in growth rate of larvae in the pack ice 
habitat between early and late winter. Thus we rejected the null hypothesis. 
Results are interpreted with regard to larval size, interannual variation in
seasonal sea ice dynamics, and other factors.