Ornithogenic (bird-formed) SoilsExtensively developed in Antarctica and rare outside of Polar regions
Characterized by a specific lithology due to penguin nesting behavior
Includes a combination of soil, pebbles, guano, highly rich in organicmatter (feathers, bone, eggshell, prey remains)
These soils provide a rich assortment of preserved tissues of penguinsand their prey:
penguin bones and feathers, mummieseggshellsfish bones, otolithssquid beaks
Invaluable for numerous types of analyses:
Radiocarbon dating to obtain occupation historyAncient DNA for evolutionary rates in penguinsStable Isotope analyses to investigate dietary shifts through timeOxygen isotope analyses of prey remains (otoliths, squid beaks)
Ross Sea has longest record for Adélie Penguins in Antarctica and theiroccupation history there provides important data on how penguins respondto climate change
Ornithogenic soil microbiota
At active penguin colonies, soil is dominated by bacteria at92% of total biomass
Farther from colonies, algae dominates sediments (up to 96%of biomass)
Surprisingly, invertebrates (nemotodes, springtails) were not more diverse in active colony soils, tardigrades absent
Possible due to high nutrient and salt content limiting invertebrateabundance and diversity
After the colony is abandoned, plant biomass outside the colony continues to dominate
Lichens replace algae as the soils dry
Bio-elements in Ornithogenic Soils--defined as those mineral elements that accumulate in soil due to
deposition of guano--show distinct profile with depth in natural versus ornithogenic
deposits--found in ornithogenic soils and sediments--can be used to assess past population sizes, occupation history--first investigated in 1950s and 1960s, considerable more work in past
decade by Chinese scientists
Bio-elements in Ornithogenic Soils
PhosphorusNitrogenZincFluorineBariumSulfurCalciumCopperSeleniumStrontiumCadmiumArsenicSodium
500 m
CapeBird
300 m
300 m
100 m
500 m
MB4
MB1
MB6
CL2
-2
-1
0
1
2
0500100015002000
-2
-1
0
1
2
100015002000
-1.5
-0.5
0.5
1.5
2.5
3.5
0500100015002000
-2
-1
0
1
2
3
0500100015002000
MB6
MB4
CL2
MB1
Age (AD)
PC-1
load
ing
for b
io-e
lem
ents
Magrationat about
1300~1400 AD
a b
Penguin population change inferred from four profiles from Cape Bird and a possible migration route during 1300~1400 AD.
Windmill Islands: > 105,000 breeding pair of Adélie Penguins
• 14 locations on southern and northern islands
• 300 % increase since 1950s
• numerous unstudied abandoned colonies
• Hundreds of abandoned mounds, or subcolonies, located throughout the area
• 17 excavated, mostly in N. islands
• 40 radiocarbon dates
• abundant prey remains (fish, squid)
Paleodietary Non-krill Remains
• 23 spp. of teleost fish from otoliths
• 3 spp. squid from beaks• Antarctic Silverfish (Pleuragramma antarcticum and squid (Psychroteuthis glacialis) most abundant taxa represented• Significant variation in relative abundance of these two prey with time periods
0 Modern1 78 – 460 cal yr B.P.2 1901 - 22863 2887 - 35204 3681 - 42345 4178 - 46256 5293 - 56427 5677 - 60898 6392 - 70119 6860 - 760710 7403 - 833911 7916 - 817812 8475 - 9284
P < 0.001