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Abstract LIFE UNDER ANTARCTIC PACK ICE: A KRILL PERSPECTIVE Langdon B. Quetin and Robin M. Ross The life cycle of the Antarctic krill, Euphausia superba,
intersects with the expansion and contraction of annual pack ice.
Consequently, the circumpolar distribution of krill has often been
defined as generally limited to an area bounded by the maximum extent
of pack ice. Pack ice has both direct and indirect effects on the
life cycle of krill. During the austral winter larval krill are
found in direct association with the underside of the ice and feed
on the small plants and animals that constitute the sea ice microbial
community, a relatively abundant food source compared to food sources
in the water column in winter. Indirectly, melting pack ice in late
winter or early spring stabilizes the water column and promotes
growth of the preferred food of krill, which, in turn, likely provides
the fuel for egg production during the summer months. Thus the warming
trend west of the Antarctic Peninsula and decreasing winter ice
duration has implications for the population dynamics of krill.
Antarctic krill studies involve diverse sampling tools that are
dependent on the size of the krill during a particular stage of
their life cycle, where they are found, and the nature of the study
itself. In particular and pertinent to the topic of diving in polar
research, diving techniques developed to allow both observation
and sampling of krill in their winter pack ice habitat have greatly
enhanced the research.
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