International Polar Year 2007–2008 - WMO

shifts in coastal marine productivity and biodiversity.
Surveys on the colonization of newly ice-free areas
under water and on land were conducted. Species like
the Antarctic limpet, Nacella concinna, expand the time
during which they stay in the Antarctic intertidal zone.
Near the U.K. Rothera station, limpets were shown to
overwinter in the intertidal zone (Waller et al., 2006),
while at King George Island this is still not absolutely
clear. Adaptive strategies under environmental strain
include self-induced hypoxia in limpets trapped
outside the water during low tides. Limpets lacking
the adaptation in shell morphology could not produce
the hypoxic response when exposed to air (Weihe and
Abele, 2008).
Antarctic sea ice
Two major Antarctic sea ice field programs were
undertaken under the umbrella of “Antarctic Sea ice
in IPY”. The Sea Ice Physics and Ecosystem eXperiment
(SIPEX) was an Australian-led program that took
place in East Antarctica (115-130°E). The Sea Ice Mass
Balance of Antarctica (SIMBA) experiment was a U.S.led
program that focussed on the Bellingshausen Sea
region (80-120°W). The voyages were near coincident
in time and provided a unique opportunity to examine
regional differences in sea ice conditions.
The experiments were highly multi-disciplinary,
with the overarching goals of improving our understanding
of the relationships among the physical sea
ice environment, the biological systems within the
ice habitat and the broader links to Southern Ocean
ecosystem dynamics and top predators. Key questions
that motivated the effort during the IPY include: What
is the relationship between ice thickness and snow
thickness over spatial scales measured by satellite laser
altimetry? How is the distribution of sea ice algae
and krill under the ice related to the ice and snow
thickness distribution? How is biological primary and
secondary productivity affected by winter sea ice extent
and properties? And what are the drift characteristics,
and internal stresses, of sea ice in the region?
IPY observations
Sea ice and snow thickness affect the interaction
between atmosphere and ocean, biota and ocean
circulation, and are therefore essential measurements
of any sea ice field campaign. In both programs, the
thickness of snow and ice were measured in a number
of different ways including drill-hole measurements
across ice floes (Fig. 2.3-13), airborne altimetry and
ship-based techniques such as electromagnetic
induction, underway observations using the ASPeCt
(www.aspect.aq/) protocol and downward-looking
video cameras.
Satellite laser altimetry calibration and validation
using a combination of in situ and aircraft-based
measurements was a key goal of both programs. The
schedule of NASA’s Ice Cloud and land Elevation Sat-
Fig. 2.3-11. Sea floor
organisms observed
with an ROV after
the Larsen A/B ice
shelves collapsed (left
and centre) and in
the Eastern Weddell
Sea (right). Species
that were adapted
to the oligotrophic
under-ice conditions
(stalked brittle stars,
left) will become
extinct in that area.
Pelagic key organisms
and benthic pioneers
(sea-squirts, centre)
immigrate and grow.
Complex benthic
communities, as in
the Eastern Weddell
Sea (sponges, right),
will establish in
centuries.
(Photo: J.Gutt ©AWI/MARUM,
University of Bremen)
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