PENGUIN PALEOHISTORY AND CLIMATE CHANGE IN THE ROSS SEA REGION
Steven D. Emslie
Department of Biological Sciences
University of North Carolina
Wilmington, NC 28403
Hundreds of thousands of Adelie penguins (Pygoscelis adeliae) occur along the Victoria Land
Coast and in the Ross Sea region, Antarctica. The chronological extent of their occupation of
this region is unknown, but research by Baroni and Orombelli (1991, 1994) has provided
important data on penguin paleohistory (13,000 B. P. to the present) in relation to sea ice
conditions, glacial retreat, and climate. In addition, previous research at abandoned and active
penguin colonies in the Antarctic Peninsula has indicated that Adelie penguin diet varies with
climate as well as with latitude in that region (Emslie et al. 1998; unpubl. data). The cause for
these variations is unknown and in need of additional investigation. Preliminary data gathered
by the author in the Ross Sea region in 2001 currently is under analysis and may indicate similar
trends as in the peninsula. The Victoria Land Program offers a unique opportunity to further
develop international collaboration in addressing these and other questions related to penguin
paleohistory and climate change in this region.
Adelie penguins need open water near their breeding colonies to successfully raise their chicks.
Many abandoned colonies ranging from hundreds to thousands of years old are located along
coastal margins that currently no longer have persistent open water each season that would
ensure reproductive success. Long-term shifts in temperature and sea ice conditions obviously
have influenced population movements and colony locations of this species. Thus, additional
investigations of abandoned penguin colonies potentially can provide proxy data for sea ice
conditions, and climate change, in the past. Moreover, organic remains preserved in these sites
(penguin tissue, eggshell, and dietary remains) also can yield considerable information on how
penguins respond to climate change with shifts in diet and foraging locations.
Research on abandoned colonies on Ross Island and along the Scott Coast was initiated by the
author in January/February 2001 (see http://www.uncwil.edu/tc/antarctica2/antarctica.html). Ten
abandoned and three active Adelie penguin colonies were located and sampled for organic
remains. Radiocarbon dates on penguin bones and tissue from these excavations are pending.
Many of these sites originally were identified and dated by Baroni and Orombelli (1994); several
others were sampled for the first time and include one at Cape Barne (77º 34’ 33” S, 166º 14’
32” E) that is the most southern Adelie penguin colony, past or present, known in Antarctica.
Areas of ice-free terrain farther south from Cape Barne, including islands and capes south of the
Ross Sea Ice Shelf, were surveyed but no additional sites were located.
The radiocarbon chronology that will result from these analyzes will supplement that published
by Baroni and Orombelli (1994). These authors identified a period of penguin population
expansion, the penguin ‘optimum,’ at 3000-4000 B. P. They hypothesize that a warming event
at that time allowed penguins to extend their breeding colonies farther to the south in the Ross
Sea than their present distribution. Data gathered by the author at Cape Barne and other
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localities may lend support to this ‘optimum’ warming event. In addition, many of the
abandoned colonies are located on raised beaches along the Victoria Land coast. Radiocarbon
dates on penguin remains from these sites will provide a minimum age for exposure of these
beaches above sea level and will aid in developing sea level curves for this region. This research
can be completed in collaboration with geologists currently investigating sea level change along
the Victoria Land coast (e.g., Berkman et al. 1998; Hall and Denton 1999).
Several other collaborative studies can be completed with organic remains from abandoned
colonies that are pertinent to the Victoria Land Program. These studies include investigations of
ancient DNA, isotopic analyses of eggshell fragments, and comparisons of past and present diet
of penguins with latitude. Studies of ancient penguin DNA were initiated by Dr. David Lambert
(D.M.Lambert@massey.ac.nz) and Peter Richie in the Ross Sea region in 1998
(http://www.massey.ac.nz/~pritchie/methods.html). A collaborative project currently is being
developed with Dr. Lambert to identify the mitochondrial lineages that can be traced from living
to subfossil Adelie penguins. This research will help track changes in the geographic
distribution of major populations that may be correlated with episodes of climate change. Dr.
David Ainley (Dainley1@cs.com) currently is investigating the foraging ecology and diet of
Adelie penguins on Ross Island. Data collected from abandoned sites, including paleodiet
information, can be compared with his results in another collaborative effort. In addition,
isotopic analyses (Carbon, Nitrogen, and Oxygen) of penguin eggshell from active and
abandoned colonies may provide signatures that are indicative of specific water masses and
foraging areas currently used by penguins. Similar signatures from eggshell fragments in
abandoned colonies could help trace shifts in diet and foraging locations that can be correlated
with the paleoclimatic record.
Numerous other abandoned and active penguin colonies occur from Cape Adare south to the
Drygalski Ice Tongue in the Victoria Land region (Baroni and Orombelli 1991, 1994).
Additional investigations at these sites are warranted. Staging areas for this research could be
established at Terra Nova Bay and Cape Hallett as a part of the Victoria Land Program. This
research would provide a latitudinal gradient of penguin occupation (past and present), a
database of radiocarbon dates that can be used to evaluate changes in sea ice conditions through
time, and organic remains dating from the late Pleistocene through Holocene that can be
analyzed with collaborative investigations on living penguins, ancient DNA, and isotope
geochemistry.
References Cited
Baroni, C., and G. Orombelli. 1991. Holocene raised beaches at Terra Nova Bay, Victoria
Land, Antarctica. Quaternary Research 36: 157-177.
Baroni, C., and G. Orombelli. 1994. Abandoned penguin colonies as Holocene paleoclimatic
indicators in Antarctica. Geology 22: 23-26.
Berkman, P. A. et al. 1998. Circum-Antarctic coastal environmental shifts during the late
Quaternary reflected by emerged marine deposits. Antarctic Science 10: 345-362.
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Emslie, S. D., W. Fraser, R. C. Smith, and W. Walker. 1998. Abandoned penguin colonies
and environmental change in the Palmer Station area, Anvers Island, Antarctic Peninsula.
Antarctic Science 10: 257-268.
Hall, B. L. and G. H. Denton. 1999. New relative sea-level curves for the southern Scott
Coast, Antarctica: evidence for Holocene deglaciation of the western Ross Sea. Journal of
Quaternary Science 14: 641-650.
Figure 1. Map of the Victoria Land Coast and Ross Sea region showing the location of
abandoned and active Adelie penguin colonies discussed in the text.