Issue 17: 2009 - Australian Antarctic Division

40 Pages·2009·6.13 MB·English

AusTRAlIAN
ANTARCTIC
mAgAzINe ISSUE 17 2009
AusTRAlIAN
ANTARCTIC
mAgAzINe ISSUE 17 2009
CONTeNTs
The Australian Antarctic Division, a Division of the SCIENCE
Department of the environment, Water, Heritage and
managing human impacts 1
the Arts, leads Australia’s Antarctic program and seeks
to advance Australia’s Antarctic interests in pursuit Penguins in press 2
of its vision of having ‘Antarctica valued, protected
evolution in the Antarctic 4
and understood’. It does this by managing Australian
government activity in Antarctica, providing transport Adélie penguin population dynamics: 18 years in a colony 6
and logistic support to Australia’s Antarctic research
Darkness sheds light on krill reproduction 9
program, maintaining four permanent Australian
research stations, and conducting scientific research Predicting the location of vulnerable marine ecosystems 10
programs both on land and in the southern Ocean.
Seeking answers to fishy questions 12
Australia’s four Antarctic goals are: Seabird saving device wins award 15
• To maintain the Antarctic Treaty System
Award for zooplankton website 15
and enhance Australia’s influence in it;
• To protect the Antarctic environment; Australian Antarctic science season 2009–10 16
• To understand the role of Antarctica in science dives into dirty issue 20
the global climate system; and
southern Ocean Research Partnership 22
• To undertake scientific work of practical,
economic and national significance. grey-headed albatross receives greater protection 22
Cameras to spy on petrels 23
Australian Antarctic Magazine seeks to inform the
Australian and international Antarctic community seeing through deep ice 24
about the activities of the Australian Antarctic
program. Opinions expressed in Australian Antarctic
TECHNOLOGY
Magazine do not necessarily represent the position
of the Australian government. Marine animals downsize in sea change 25
Australian Antarctic Magazine is produced twice a year Building technology in Antarctica 26
(June and December). All text and images published
in the magazine are copyright of the Commonwealth Water finally flows at Davis 27
of Australia, unless otherwise stated. Editorial
Freezing the natural moment 28
enquiries, including requests to reproduce material,
or contributions, should be addressed to: Three-dimensional medicine 29
The editor subantarctic resupply a lARC 29
Australian Antarctic Magazine
Australian Antarctic Division
PEOPLE
203 Channel Highway
Kingston, 7050 Antarctic Medal winner flying high 30
Tasmania, Australia.
mathematics and conservation combine for a eureka moment 32
Australian Antarctic Division
Telephone: [phone]
(International 61 3 6232 3209) IN BRIEF 34
email: [email protected]
Facsimile: [phone]
FREEZE FRAME 37
(International 61 3 6232 3288)
editor: Wendy Pyper
editorial Advisory Committee: sally Chambers,
John gunn
Production: Jonothan Davis, Jessica Fitzpatrick, FRONT COVeR: AlIsON lesTeR AND PeARl NABegeyO
Glenn Jacobson, Mathew Oakes Australian Antarctic Arts Fellow, Alison Lester, asked school children around
graphic Design: Red Jelly Australia to draw their visions of her Antarctic adventure in 2005. Pearl Nabegeyo OT
m
IssN 1445-1735 (print version) from Gunbalanya in east Arnhem Land sent Alison a 2 cm high drawing of an WIl
emperor penguin and chick. Alison enlarged the image on watercolour paper and D
R
Australian Antarctic Magazine can be viewed online: says ‘I painted the dark indigo of an Antarctic sky and swirled snow across it in HA
<http://www.aad.gov.au/magazine>. spirals that echoed indigenous dot painting’. RIC
AAD9614rj
AustrAliAn AntArctic mAgAzine issue 17: 2009
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Ice breaking off ice cliffs in Geoffrey Bay at Casey. n p
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MAnAging huMAn iMpAcTS
A number of scientific This issue of the Australian Antarctic Magazine fishery in Australia’s Exclusive Economic Zone
looks at some of the different ways species or (page 12). As well as enabling ccAMLR to set
research projects conducted
ecosystems can be used to help understand and sustainable catch limits for the fishery, the work
in Antarctica focus on manage human impacts on a number of scales. is revealing some interesting facts about this
This includes, on page 20, an environmental mysterious monster of the deep.
particular species or assessment of the sewage outfall at Australia’s
This issue also focuses on some of the
Davis station. Various biological, physico-
ecosystems that can act as new technology making Antarctic work and
chemical and ecotoxicological studies on
life easier. casey and Davis stations are
microbial communities and invertebrates
early warning systems for
such as worms, crustaceans and algae, will undergoing significant infrastructure
environmental change as a help scientists determine the effect, if any, improvements, with energy efficiency and
of sewage on the environment and inform flexibility critical requirements (page 26).
result of human activities. the installation of an effective replacement Antarctic doctors are also benefiting from a
wastewater treatment system for the station. new three-dimensional ultrasound machine
(page 29), while a new reverse osmosis plant
Taking a slightly different tack, scientists
Due to their significant appetite for krill, Adélie is allowing Davis expeditioners to enjoy an
are building up a picture of the relationships
penguins, for example, have played a major experience most people take for granted –
between organisms’ life history characteristics
role in helping scientists develop a system to daily showers (page 27).
(e.g. reproduction and life span) and their
monitor the potential impacts of the Southern
environment, to predict whether they are Finally, we celebrate the achievements of two
Ocean krill fishery for almost 20 years (page 6).
vulnerable to bottom fishing in the Southern talented and dedicated individuals: Antarctic
More recently, this research has revealed
Ocean (page 10). Maps of geophysical features, Medal winner David pullinger, whose work as a
the close relationship between the sea ice
ocean depth and currents are also being used helicopter pilot has supported scientific research
environment and the birds’ breeding success and
to predict the location of environments likely in Antarctica for 20 years (page 30); and Eureka
survival, which also makes them a potentially to support vulnerable organisms. Through the prize winner and mathematician, Dr ian Ball,
useful ‘indicator’ of the impacts of climate commission for the conservation of Antarctic whose Marxan software is contributing to marine
change, before more widespread effects unfold. Marine Living Resources (ccAMLR), the work is and land conservation planning around the world
Such indicator species provide important helping to safeguard these ‘vulnerable marine (page 32).
ecosystems’ by preventing fishing in susceptible
information for conservation and management
Enjoy your reading.
areas until appropriate management actions
in Antarctica and elsewhere. Their study also
are established.
provides a window of opportunity to initiate
management measures that help protect other To avoid a repeat of past mistakes, scientists
species or ecosystems from the consequences are conducting detailed scientific research
of human activities, or to manage or reduce the on the biology, distribution and movement of WEnDY pYpER
impacts on them. patagonian toothfish to ensure a sustainable Editor
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AustrAliAn AntArctic mAgAzine issue 17: 2009
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penguin research made the colonies there are in the Australian Antarctic this study Dr Wienecke recommends a change
Territory (AAT), with estimates of 13, 15 and to the listing status of emperor penguins by
scientific spotlight this 17 colonies. in addition, some reported colony the international union for the conservation of
sightings have never been confirmed. nature, from ‘of least concern’ to ‘data deficient’.
year, as Australian Antarctic
To try and reduce the uncertainty over the ‘As we have no firm understanding of the
Division scientists clarified
number of emperor penguin colonies in the number of existing breeding colonies, we
AAT, Dr Wienecke collated observations from cannot estimate the size or trends of the global
how many emperor penguin
expedition narratives, log book entries, population of emperor penguins. We need to
colonies call the Australian published literature, maps, photographs and explore the coastline of the AAT in detail to help
satellite images, from the 1950s to today. resolve this,’ she says.
Antarctic Territory home, She then excluded sightings of birds without
The application of remote sensing technology
chicks, airborne sightings not confirmed by
and revealed some good may prove an efficient and effective way to
a ground visit, and sightings that were never
do this. Recently, the British Antarctic Survey
confirmed on subsequent visits.
news on the resurgence of used satellite images of the Antarctic coastline
‘When emperor penguins are observed in to identify likely emperor penguin colonies,
king penguins on Macquarie
January/February, there is a possibility that based on faecal stains. ground visits or high
island, after their encounter they have gathered at a moult location, which is resolution images can now be used to confirm
not necessarily the same as their breeding site,’ these sightings.
with near-extinction. Dr Wienecke says.
‘This is an exciting new development that has
‘Even in winter, a group of emperor penguins is brought us one step closer to assessing how
not immediately indicative of a breeding colony many colonies there really are, both in the AAT
Counting emperor penguin colonies unless breeding activities are observed – such as and right around Antarctica,’ Dr Wienecke says.
When is a cluster of emperor penguins not incubation or the presence of chicks. Juveniles
a colony? According to Australian Antarctic and sub-adults are rarely seen at the colonies More information:
Division penguin biologist, Dr Barbara and it is likely that they congregate anywhere
Barbara Wienecke. Emperor penguin colonies in
on the ice.’
Wienecke, emperor penguins (Aptenodytes
the Australian Antarctic Territory: how many are
forsteri) congregate when they moult or mate. Dr Wienecke’s review identified 11 confirmed there? Polar Record, 45(0): 1–9, 2009.
however, it is only groups of penguins with breeding colonies in the AAT and 8 unconfirmed
Barbara Wienecke. The history of the discovery
chicks that can be truly identified as a breeding breeding colonies. Two of the confirmed
of emperor penguin colonies, 190–2004. Polar
colony. This distinction has contributed to colonies, at Taylor glacier and Auster, are part
Record, (in press).
confusion over how many emperor penguin of long-term population studies. As a result of
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Locations of confirmed and unconfirmed colonies of emperor penguins in the Australian Antarctic Territory. Location of past and present king penguin colony sites
on Macquarie Island.
King penguin populations bounce back A second colony at Lusitania Bay increased ‘This may be because their breeding cycle
from the brink from a remnant population of about 3400 birds, ensures that some proportion of the breeding
in 1930, to about 170 000 breeding pairs in and non-breeding populations are absent from
Macquarie island king penguins came close
2000. This population has begun to spill over breeding islands during the year, providing a
to extinction in the late 19th and early 20th
into nearby breeding ground, which includes buffer and continued potential for population
centuries, as blubber oil gangs supplied a
The isthmus. growth,’ he says.
commercial oil market and collected eggs for
food. At least two breeding colonies, thought ‘currently there are four king penguin colonies Dr van den hoff proposes that a non-invasive
to number in the hundreds of thousands of on the east coast of Macquarie island: one each study of the gadget gully colony be established,
birds, were reduced to piles of bones or a few at Lusitania Bay, green gorge, Sandy Bay and to help scientists understand the breeding cycle
thousand birds between 1810, when the island now The isthmus,’ Antarctic Division biologist, of king penguins at Macquarie island and clarify
was discovered, and 1912. however, once Dr John van den hoff, says. how this cycle responds to changes in food
exploitation ceased in 1918 and the island availability, due to climate variability.
became protected, there was a resurgence in Evidence of local king penguin population
the population of these resilient birds. fluctuations prior to human interference is also More information:
apparent on the island, possibly due to landslips,
in 1995 scientists from the Australian Antarctic John van den hoff, clive R. McMahon and iain
storm events, volcanic activity, food availability,
Division observed the first eggs laid near the Field. Tipping back the balance: recolonization
and a ‘catastrophic mid-holocene event’.
site of one mass slaughter, at gadget gully of the Macquarie island isthmus by king
on The isthmus (see map). The first chick was Dr van den hoff says the ability of king penguin penguins (Aptenodytes patagonicus) following
fledged in 1996. Over the next five years the populations to overcome such odds suggests extermination for human gain. Antarctic Science,
colony increased on average 66% per year. that they are resilient to catastrophic events. 21(3): 237–241, 2009.
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King penguins at Gadget Gully in 2008. EVE
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Researchers uncovering ancient penguin remains at Inexpressible Island, Antarctica. ROFESS
p
EVOLuTiOn in ThE AnTARcTic
Adélie penguins in Studying evolution is not always easy. You need At inexpressible island (so named because
a lot of time and the opportunity to study many the early explorers could not think of a word
Antarctica are an ideal
individuals. Also, it’s preferable to work on a bad enough to describe it), our research team
species on which to study species that has been unaffected by humans and took blood samples from a large number of
that has lived in one place for a long time, in penguins in the colony there. With the help of
the speed and mechanisms an environment that has changed a lot. if you’re our collaborator, professor carlo Baroni from the
interested in ancient DnA, you’d prefer them to university of piza, we also collected sub-fossil
of evolution. Recent research
be ‘stored’ in cold conditions. Adélie penguins in penguin bones and radiocarbon dated some of
using modern and ancient Antarctica are ideal! these to determine their age – estimated to be
around 6000 years old.
To most people evolution is the idea that the
samples of the birds’ DnA
composition of the earth’s biodiversity has next, we isolated nine sets of nuclear DnA
has shown that mutation changed over long periods of time. To biologists sequences from both the modern and the
it also means something more specific; namely ancient samples and examined the sequences
rates in the DnA can be
changes in populations or species over shorter for changes in the frequencies of different gene
used as a proxy for the rate periods of time. At a practical level it usually variants (‘alleles’). in fact, we did record some
comes down to changes in the ‘frequency’ changes in the frequencies of alleles over time.
of evolution. The discovery (occurrence) of particular genes or DnA This was the first demonstration of evolution in
sequences over time. the sense of gene frequency shifts over a 6000
could improve the dating of
year period. Other studies have shown changes
how, precisely, might we go about detecting
evolutionary events, such over much shorter time periods.
evolutionary changes in the frequencies of genes
as the divergence of species in populations over time? We decided to study As part of our study we also wanted to measure
the large numbers of Adélie penguins nesting the speed or rate of evolution; that is, how
from a common ancestor. around the Antarctic coastline during summer, fast changes in the genetic composition of
and the bones of their ancestors buried beneath the penguin population occurs. We took a
these colonies. new approach to the problem by comparing
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Adélie penguins nest in ice-free areas around the Excavation of a long-abandoned penguin colony in search of sub-fossil bones for DNA work.
coast of Antarctica during summer. Underlying these
colonies are bones of their ancestors that harbour
some of the best ancient DNA yet discovered.
mitochondrial DnA sequences from living birds, methods developed by professor Mike hendy these new molecular techniques can be reliably
and his colleagues from the Allan Wilson centre used to time at least relatively recent divergence
with those from sub-fossil bones up to 44 000
for Molecular Ecology and Evolution in new events; that is, the genetic separation of related
years old, excavated from beneath the colonies.
Zealand, we were able to use this large number organisms from a common ancestor.
(Mitochondria are small structures within cells
of observed mutations to estimate the overall
that provide most of a cell’s energy.) For more information and a list of scientific
rate of mutation in penguins. This mutation rate
publications see:
By comparing the modern and ancient turned out to be the same, statistically speaking,
mitochondrial DnA sequences, we were able as the rate of evolution that we had determined www.griffith.edu.au/environment-planning-
to directly measure changes in DnA lineages using old penguin bones. Our findings suggest architecture/griffith-school-environment/
over time and estimate the speed of evolution. that mutations are the driving force for the high staff/professor-david-lambert and
Surprisingly, we were able to show that the rate of evolutionary rate in Adélie penguins. www.sbs.auckland.ac.nz
mitochondrial evolution is about six times faster
These findings suggest that estimates of both DAViD LAMBERT1 and cRAig MiLLAR2
than has been estimated using other methods.
mutation and evolution might well be similar
1 Professor of Evolutionary Biology, Griffith
Why might DnA sequence evolution be so fast? in other species and that we can use rates of
University, Nathan, Brisbane, Australia
One possibility is that Adélie penguins have a ‘neutral’ mutation (where there are no differences
2 Allan Wilson Centre for Molecular Ecology
very high rate of molecular evolution, simply between the original gene and the mutant) as
and Evolution, School of Biological Sciences,
because they have a high rate of mutation for a proxy for evolutionary rates, when these data
University of Auckland, New Zealand
this part of the mitochondrial genome? are available. Finally, our findings mean that
To answer this question, we spent four summers
in the Antarctic collecting samples from pairs of
breeding penguins. Then, using blood samples
from mothers and their chicks, we sequenced the
same piece of mitochondrial DnA for which we
had measured the speed of evolution using the Nucleus
44 000 year old sub-fossil bones.
Mitochondrial DnA is inherited quite differently
to the nuclear DnA of chromosomes. While
Animal tissue
offspring inherit nuclear DnA from both parents, e.g. blood, bones etc
they typically inherit mitochondrial DnA only CELL
from their mother. So in this experiment, we Mitochondria
expected to find the same mitochondrial DnA
sequence in all chicks as we found in mother Pairs of chromosomes,
two copies of each gene
Adélie penguins; except of course for any
mutations. As mutations are rare, we did not
Hundreds of copies of mt DNA
expect to find many of them.
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however, we were surprised to find a large An Animal cells contain DNA sequences in the chromosomes of the nucleus and a smaller
number of mutations. using new analytical ViVi genome found in the mitochondria (mt DNA).
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Adélie penguins are an important indicator species for the CCAMLR Ecosystem Monitoring
Program which aims to monitor and detect changes in the marine ecosystem due to
environmental variability and human activities (such as krill fishing). As the pink
staining demonstrates, this colony has been enjoying a diet rich in krill.
ADéLiE pEnguin pOpuLATiOn DY nAMicS: 18 YEARS in A cOLOnY
Antarctica’s population of For example, their notable decrease on need to distinguish between fisheries’ impacts
the Antarctic peninsula is thought to be and change due to ‘natural’ environmental
Adélie penguins (Pygoscelis a direct response to a reduction in sea ice as variability, but climate change was not then
a consequence of climate change. Across their seen as a potential confounding influence. now
adeliae), which numbers
distribution of ice free breeding sites along there is much discussion within ccAMLR about
the Antarctic coastline and offshore islands, how to distinguish between climate change and
approximately 2.5 million
their population trends vary, with some fisheries’ impacts; an incredibly difficult task.
breeding pairs, closely populations decreasing, some remaining
Béchervaise island, near Mawson station, was
stable and others increasing.
established as a cEMp site in 1989 and the
reflects underlying changes
Although Adélie penguins have a varied diet that data collected from this site forms the basis of
in the lower levels of includes fish, squid, amphipods and jellyfish, Australia’s contribution to the cEMp. Although a
they eat large quantities of Antarctic krill – krill fishery was operating in this area then, it has
the food web and the ice which is the subject of a major Antarctic fishery. subsequently concentrated in the South Atlantic,
and there has been no krill fishery off East
This penchant for krill and their dependence on
environment on which they Antarctica since the early 1990s. This has provided
the sea ice environment makes Adélie penguins
an opportunity to examine variability in cEMp
an important ‘indicator’ species for the ccAMLR
are dependent. parameters in the absence of fisheries’ impacts,
(commission for the conservation of Antarctic
to provide baseline data and the ability to explain
Marine Living Resources) Ecosystem Monitoring
the cause of natural variation, particularly the
program (cEMp).
links with the environment. We now have up to
The Australian Antarctic Division has played a 18 years of consistently collected data with which
key role in cEMp since it was established in the to assess population trends and the underlying
mid-1980s, when nations were encouraged to processes that influence population dynamics.
monitor indicator species to detect potential here we describe results for two important factors
negative impacts from the fishing industry. Back contributing to population change: penguin
then, ccAMLR recognised that monitoring would reproductive success and penguin survival.
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ADéLiE pEnguin pOpuLATiOn DY nAMicS: 18 YEARS in A cOLOnY
Reproductive success to forage. it was clear that the presence of marine environment, as the sea ice transforms
extensive fast ice increased the duration of from its minimal extent in March through to its
For some years we were aware that the ability
foraging trips, thereby reducing the frequency maximal extent in September.
of parents to feed their offspring was related
of feeding chicks, and ultimately leading to
to the extent of ice around a breeding colony. Estimating survival requires the detection of
their demise. But there were other factors at
however, it wasn’t apparent what type of ice individuals over multiple years through a ‘mark-
work too. Many foraging trips in some years
was important (fast ice1 or sea ice, for example) recapture study’. Each year at Béchervaise island
weren’t long enough to reach the fast ice edge,
or where or when the presence of ice mattered. up to 300 chicks are tagged with micro-chips
indicating that penguins were able to forage
To address this we examined annual penguin and their presence at the island in subsequent
within the fast ice area in some years but not
reproductive success in relation to the ice years is determined by manual tag readers and
in others. Furthermore, extensive fast and sea
environment obtained from satellite images. an automated monitoring system. Through these
ice, or the oceanographic processes driving
Through a series of statistical analyses we found detection methods we can generate a series of
the timing of sea ice break-out, may also be
that reproductive success is clearly related detection histories for every bird that has been
associated with reduced prey availability near
to the amount of ice present, particularly the tagged over the last 18 years and use them to
Béchervaise island.
area immediately adjacent to the breeding site estimate penguin survival. Our results indicate
(Figure 1). Extensive fast ice during the ‘guard that young penguins have highly variable survival
Adélie penguin survival
stage’ of the chick rearing period, when chicks over their first winter, while survival of the older
in stark contrast to the relative ease with which
require at least one parent to remain at the birds is more consistent through time (Figure 2).
we can examine the summer-based activities
nest with them, meant that few chicks survived.
of reproduction by deploying field biologists understanding the processes driving Adélie
Additionally, having some sea ice further away
to measure population parameters, measuring penguin survival is challenging. Statistical
from the colony, but still within their foraging
mortality directly is near-impossible. To make analyses suggest a link between penguin
range, improved breeding success when fast ice
matters worse, most mortality is thought to survival and the ice environment at their
close to the breeding colony was limited.
occur during the inter-breeding period when presumed winter foraging grounds, some
Reproductive success was low in years with Béchervaise island penguins travel up to 1500 km away from their breeding site
extensive fast ice, in part because of the forced 1500 km away from their breeding site. This nine (Figure 3). This influence was most apparent
traverse across the ice to reach open water month period also sees a dramatic change in the during the deep austral winter when the sea
1 Fast ice is ice attached to the continent. 77
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ice changes rapidly. For fledgling penguins,
too much ice was detrimental to their survival,
whereas for the older birds either too much or
too little sea ice was detrimental. While survival
of the older birds was strongly associated with
the environment, there was a large amount of
variability in the survival of the younger birds
that we are yet to explain. understanding the
underlying mechanisms which result in this
association between penguin survival and the
environment requires further examination of the
specific interactions between penguins and their
ice environment through satellite tracking and
finer resolution satellite imagery.
What does this mean for CEMP?
Although there has been no krill fishery in the
Mawson region in recent years, notifications to
ccAMLR suggest that the krill fishery is likely to
expand in tonnage and to new areas. Monitoring
and assessment procedures need to be available
or in place for this eventuality. The impacts of Figure 1: Breeding success plotted against ice area during the guard period; ice area calculated between 60–65ºE
climate change in the Southern Ocean will be to around 70 km north of the coastline which is the area typically covered by fast ice around Béchervaise Island.
Breeding success varies between 0, representing total reproductive failure, and a maximum of 2, representing an
complex, but the sea ice environment is likely
average of two chicks crèching per nest. As the ice extent increases, chick survival decreases.
to be affected. From our work it is clear that
this, in turn, is likely to impact directly and 110000
indirectly on Adélie penguins. interpreting
the causes of future changes will always be
difficult and subject to some doubt. knowing ) 7755
%
the nature and extent of the linkages between
(

Adélie penguin reproduction and survival and al
important environmental features such as sea viv 5500
ice, will improve ccAMLR’s ability to make the r
u
correct interpretation and from that, take the s
appropriate management actions, if the krill 2255
fishery resumes in east Antarctica.
The future 00
Expectations of how climate change is likely 1993 1995 1997 1999 2001 2003 2005
to affect different localities around the
fledgling subadult & adult
Antarctic continent need to be considered
along with our understanding of the interaction Figure 2: Estimates of annual Adélie penguin survival for fledglings in their first winter and older birds based on
between penguins and the ice environment, mark-recapture studies at Béchervaise Island. Over winter survival of young penguins is highly variable, while older
birds demonstrate a more consistent survival pattern.
to determine likely population change in the
future and to detect change as it occurs.
This is best done through long-term studies
such as the Béchervaise island monitoring
program, in conjunction with detailed studies
on the foraging locations of predators and
environmental conditions at those locations.
We intend to continue the long-term monitoring
of Adélie penguins at Béchervaise island and
expand the regular monitoring of a selected
suite of parameters for populations in the
Australian Antarctic Territory through surveys.
new technologies will allow us to determine
their broader status and trends and to relate this
to changes in the environment. Future tracking
studies are also planned to determine where
and under what environmental conditions the
penguins are foraging during the austral summer
and winter months.
LOuiSE EMMERSOn and cOLin SOuThWELL Figure 3: Expected Adélie penguin travel route for Béchervaise Island penguins during their winter migration, based
Southern Ocean Ecosystems program, on previous satellite tracking studies. The region highlighted (left of graphic) shows an area where ice is thought to
influence the survival of adult and fledgling Adélie penguins. Ice conditions presented here are based on satellite
Australian Antarctic Division
images from May 1993.
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