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)

Ornithogenic Soil

Gravel terrace and interface

Pebble concentration

Biscoe Point,Antarctica

Grass and lichen

The enriched nutrients in the soil enhance vegetative growth

Soils dry over time, but still retain guano smell

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

Note algae outside of coloniesTrampling by penguins prevents growth within the colony

After the colony is abandoned, plant biomass outside the colony continues to dominate

Lichens replace algae as the soils dry

Lichen growth over an ancient colony

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

Cape Bird, Ross Island

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.

A 9000-Year Record of Adélie Penguin Occupation and Diet in the Windmill Islands, East Antarctica

Site Locations

N. islands

S. islands

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

• Adélie Penguin occupation in Windmill Islands

is longest continuous record for the species

• Data help refine geological record for deglaciation

• Significant variation in prey abundance in sediments through time, but not correlated with climate change