The subantarctic seas are some of the richest on Earth,
and there is a genuine paradox here,
for that richness exists
despite an almost total absence
of the nutrient iron.
...
The presence of sea ice somehow compensates for this,
for the semifrozen edge between salt water
and the floating ice
promotes remarkable growth of the microscopic plankton
that is the base of the food chain.
...
Despite the months of winter darkness,
the plankton thrives under the ice,
allowing the krill that feed on them
to complete their seven-year life cycle.
...
And wherever there is krill in abundance,
there are likely to be penguins, seals and great whales.
...
The Weather Makers
Tim Flannery