Encontro Ciência July. Antarctic Deserts where Life Exists at its Limits. Catarina Magalhães

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Catarina Magalhães

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Extreme Environment

Low temperatures

Low available water and humidity

Abundant freeze-thaw cycles

High salinity

Low Carbon and Nutrient concentrations

High ultra-violet radiation and winds

Dramatic physical and chemical gradients

Photo by Catarina MagalhãesPhoto by Peggy O´Day_{Photo by Nita Smith}

Organisms that survive in these extremely cold and arid

ecosystems are considered to be subject to more environmental

stresses than any other desert on the planet.

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Antarctica – “Dry Valleys”

First scientific expeditions

• “we have seen no living thing, not even a moss or lichen”

Robert Scott 1903

• Dry Valleys were described as sterilized environments

until the seventies.

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Springtails

Mites

Nematodes

Rotifers

Tardigrades

Springtails

Invertebrates

Moss

Lichen

_Algae

Vegetation

Photo by Nasa Earth Observatory

As the environmental constraints increase,

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Cary et al. 2011 Nature Reviews

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High spatial pattern of biota due to extreme

heterogeneity of biogeochemical soil properties

Historical landscape changes were identified as keystone drivers

of the distribution of taxa in the Dry Valleys.

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Dr

ift

ag

e

/ Osm

oti

c

Str

es

s

Biota diversity

Younger drifts

Weakly developed soils

Less salts content

Lower level of osmotic tolerance

more complex communities

Encontro Ciência 2016 4-6 July

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The antagonistic relationship between drift ages and diversity

is particularly evident for bacteria and cyanobacteria.

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Miers Valley

,

Beacon Valley

.

Miers Valley Beacon Valley

Miers Valley

Photo by M.Becker LIMA

Photo by Nita Smith

0 500 1000 1500 2000 0 2 4 6 8 10 UW BV BP MV

C/N

0 2000 4000 6000 8000 UW BV BP MV

Cond.

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0,0E+00 2,0E+05 4,0E+05 6,0E+05 8,0E+05 1,0E+06 1,2E+06 1,4E+06

Upper Wright Valley Beacon Valley Battleship Promontory Miers Valley

am oA gene cop ies g-1 soil AOA AOB 1.4 x 10 6 1.2 x 10 6 1.0 x 10 6 8.0 x 10 5 6.0 x 10 5 4.0 x 10 5 2.0 x 10 5 0.0 x 00

…antagonic dominances of AOA and AOB

in the different Dry Valleys analyzed…

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Photo by Nita Smith

McMurdo Dry Valleys of Victoria Land in Antarctica

How basic microbial functional capabilities like the nitrogen pathways are

maintained in extreme ecosystems

Relevance of nitrogen biogeochemistry and the microbial communities that

mediate N transformations in extreme Antarctica environments

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• Novel organisms and aspects of the ecology of microbial communities that mediate N

transformation in natural environments.

• Relevance of nitrogen biogeochemistry and the microbial communities that mediate N

transformations in extreme Polar environments.

www.cmagalhaes.com

http://www.propolar.org/nitroextrem.html

www.cmagalhaes.com

N circulation and transfer from N reach near shore

locations to N limited surrounding terrestrial habitats.

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Extreme Environments - Arctic

Understand the ice associated ecosystem and model future changes

Full annual cycle from the winter freeze-up until the summer melt

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Extreme N microbial Ecology

Mapping both physical and biological time series

data to obtain a good understanding of ecosystem

status and how systems respond to natural and

human-based threats.

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Catarina

Hugo

Maria

Joana

Marisa

Paula

Nuno

João

António

Adriana

Mafalda

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