For more than half a century, biologists
studying Antarctica focused their research on understanding how
organisms cope with the continent's severe drought and the coldest
conditions on the planet.
One thing they didn't really factor in, however, was the role played by
the nitrogen-rich droppings from colonies of cute penguins and seals --
until now.
A new study published Thursday in the journal Current Biology found the
influential excrement supported thriving communities of mosses and
lichens, which in turn sustained vast numbers of microscopic animals
like springtails and mites for more than 1,000 meters (yards) beyond the
colony.
"What we see is that the poo produced by seals and penguins partly
evaporates as ammonia," said co-author Stef Bokhorst from the Department
of Ecological Sciences at Vrije Universiteit Amsterdam.
"Then, the ammonia gets picked up by the wind and is blown inland, and
this makes its way into the soil and provides the nitrogen that primary
producers need in order to survive in this landscape."
Braving bitter temperatures, the researchers waded through fields of
animal waste -- not to mention hordes of clamoring elephant seals and
gentoo, chinstrap, and Adelie penguins -- to examine the surrounding
soils and plants using infrared gas analyzers that measured their
respiration.
Samples brought back and examined in labs revealed that there were
millions of tiny invertebrates per square meter because of the lack of
predators in their environment -- unlike in European or American
grasslands, where the number may typically be between 50,000 and
100,000.
"The more animals we get, the larger the footprint there is, and we're
finding higher diversity in those sites," Bokhorst told AFP, emphasizing
that species' richness was linked less with how cold or dry the region
was and more to the nutrients added by the excrement.
Ultimately, the research allowed the team to map the hotspots across the
Antarctic Peninsula, finding penguin colonies to be a proxy for
biodiversity.
The maps can be updated in the future using satellite imagery to
determine the size and location of breeding colonies, freeing future
scientists from having to conduct treacherous fieldwork.
- 'Ideal natural laboratory' -
For Bokhorst, Antarctica presented an "ideal natural laboratory" to
study the relationship between nutrients and biodiversity because of the
simplicity of the overall food web, in contrast to other parts of the
world where ecosystems were far more complex.
"It makes it a lot easier to find driving factors," said Bokhorst.
But the study also underscored how interconnected the continent's
ecosystem was -- and therefore its vulnerability to human activity.
All countries working on the continent are subject to the Antarctic
Treaty System, which obliges them to protect its wildlife, but Bokhorst
said the study showed "if you start poking at one end it will have an
effect at the other end."
"You need to keep a good eye that you're not overfishing the oceans so
you're not harming food supplies, otherwise you're going to have an
impact for biodiversity," he said.
The peninsula's vibrant invertebrate communities face few predators, but
the advent of tourism means there is an increasing chance people could
bring seeds or even insects with them.
These, in turn, could benefit from the soil enrichment and establish themselves, threatening the native species.
"That's a very good argument for why we should be careful with the Antarctic," said Bokhorst.
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