Antarctic octopus tells story of ice-sheet collapse

May 7, 2012 By Tamara Jones
Antarctic octopus tells story of ice-sheet collapse
Antarctic landscape.

Scientists have long been concerned that the massive West Antarctic Ice Sheet could collapse if global temperatures keep climbing. If it did, sea levels are predicted to rise by as much as five meters.

Now, genetic evidence from an octopus reveals that this may have happened at some point in the not-too-distant past – possibly as recently as 200,000 years ago.

This suggests that scientists' concerns about the state of today's could well be justified.

An international team of researchers analysed the genes of the Turquet's octopus, which lives in the Southern Ocean surrounding Antarctica. During the Census of Antarctic Marine Life, which ran from 2005 to 2010, and International Polar Year, teams of scientists collected Turquet's octopuses from all around the continent.

"We were able to take advantage of much larger sample sizes than had been collected from Antarctica before. This presented us with a unique opportunity," explains Dr. Jan Strugnell from La Trobe University, lead author of the study, published in Molecular Ecology.

Adult Turquet's octopuses only move to escape from predators. This means they tend to stay put and don't travel very much at all. So the researchers expected octopuses from different regions of Antarctica to be genetically quite dissimilar.

Antarctic octopus tells story of ice-sheet collapse
Turquets octopus.

But to their surprise, they found that the genes from octopuses taken from the Weddell and Ross Seas, on the opposite sides of Antarctica, were startlingly similar.

"The Ross and Weddell Seas are completely separate: they're about 10,000 kilometers apart," says Strugnell. "So we expected the genetics of these octopuses to be quite different."

When the climate was much warmer, sea levels would have been substantially higher, because less water would've been locked up as ice. In this situation, the Ross and Weddell Seas could have been connected.

"Ocean currents would have both facilitated and hindered the flow of genes. But the Antarctic Circumpolar Current almost certainly wouldn't have facilitated so much dispersal by octopuses that two populations have almost identical genetics," Strugnell says.

"So, we think this would only have happened if the had collapsed."

In contrast, Turquet's octopuses from other parts of Antarctica showed the level of genetic differences that Strugnell and her colleagues were expecting.

Indeed, the researchers found that the depth of the ocean and ocean currents have had a huge effect on limiting the movement of individuals.

"The do not go any deeper than 1000 meters, so populations on areas of continental shelf that are separated by deep water are very effectively isolated," explains Dr. Phill Watts from the University of Liverpool, a member of the study team.

While a previous study in 2010 provided the first evidence of a trans-Antarctic seaway connecting the Ross and Weddell Seas, this is the first of such a connection.

Of the world's three major ice sheets, scientists think the WAIS is most vulnerable to changes in the climate. Many say the ice sheet is inherently unstable and could collapse fairly quickly, making a substantial contribution to rise.

Explore further: Marine animals suggest evidence for a trans-Antarctic seaway

More information: J. M. STRUGNELL, et al. Persistent genetic signatures of historic climatic events in an Antarctic octopus, Molecular Ecology, Article first published online: 12 APR 2012, DOI: 10.1111/j.1365-294X.2012.05572.x

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4 / 5 (12) May 07, 2012
This paper provides a good example of how Global Warming is no longer a disputed issue in science but in fact is new fact upon which additional science is continuing to build.

The scientific debate has been over for the last 20 years. Word of the victory has not reached planet Conservadopia yet. That world has been on a reality blackout for the last 40 years.
May 07, 2012
This comment has been removed by a moderator.
3.8 / 5 (8) May 07, 2012
Verkle: True, but at some point one needs to move the debate to debatable science.
4.2 / 5 (10) May 07, 2012
Completely false of course.

"VD: As soon as debate is over, science ends." - Verkle

Science doesn't in any way need debate. It only needs physical measurement and a means to generalize those measurements into a set of fundamental concepts.

Clearly you know nothing about science.

Now as to the issue of Global Warming. The denialists have lost the scientific debate. That is why they are chronically yammering about the political ramifications of the science. Perceived loss of freedom, perceived loss of blah, blah, blah due to lowered Co2 emissions, etc.

4 / 5 (5) May 07, 2012
VD: I agree on your stance about GW. Not your stance on the non-debatable nature of science.
Part of science has been and still is the creation of categories and definitions, which almost always needs to be discussed.
1.6 / 5 (9) May 07, 2012
@VD: Global Warming is NOT climate change. And this is yet another article providing evidence that climate change (repeating cycle) is what is occurring. Global Warming is simply a term coined a purely political agenda. Come on man, we've been round and round about this, you know better than to mix up those terms.
5 / 5 (9) May 07, 2012
From http://en.wikiped...nk_Luntz
"Although Luntz later tried to distance himself from the Bush administration policy, it was his idea that administration communications reframe "global warming" as "climate change" since "climate change" was thought to sound less severe.[9] Luntz has since said that he is not responsible for what the Bush administration did after that time."

I wonder if Luntz still gets a thrill when some idiot falls for this.
Lex Talonis
1.2 / 5 (6) May 07, 2012
I really HATE the use of very similar names for things, like Arctic and Antarctic - because they are similar and have no bearing on the location.

By combining the word "North" or "South" with "Pole" and "Polar", we get Soupole and Soupolar and Norpole and Norpolar.


OK it's official - we have NEW words to describe and define the location of these regions.

Everything else is banned.

4.5 / 5 (8) May 07, 2012

"from Latin arcticus, from Greek arktikos northern, literally: pertaining to (the constellation of) the Bear, from arktos bear]"

Artic just means northern, and "antarctic" means "opposite of northern".

Root languages are useful sometimes.
1 / 5 (4) May 08, 2012
This paper provides a good example of how Global Warming is ...

... a joke.

It was much colder 200,000 years ago.

5 / 5 (5) May 08, 2012
And a pretty poor one at that.

ParkerTard - "... a joke."

In a year without winter, Parker Tard exposes his mental illness for all the world to see.
5 / 5 (3) May 08, 2012
"Global Warming is NOT climate change" - Extremity

But since Global Warming has been relabeled as Climate Change, it is.

I sympathize with your objection however.

"And this is yet another article providing evidence that climate change (repeating cycle) is what is occurring." - Extremity

Can you explain to us why this "cycle" that you have fabricated in your own mind, is happening 100 times faster than the regular glacial "cycles" and is in the wrong direction?

Please try to avoid the invocation of God, Angels, Space Aliens or Moon beams in your response.

5 / 5 (3) May 08, 2012
"Not your stance on the non-debatable nature of science." - bbdk

My point is not that science can not be debated, it is that science need not be debated.

Debate invariably centers around how best to "explain" the observations in terms of the existing framework of science. Such debate is entirely unnecessary. As long as theory can be rectified with observation. How is only relevant to rational human explanation of the processes being observed.

In the case of Global Warming, the "debate" on the cause is over.

The only thing left is the quibbling over second order and third order effects and it is these effects that dishonest denialists dishonestly attempt to paint as significant to the overall causation of the observed warming globe.

The science is entirely settled with regard to the first order , and most of the second order effects.

1 / 5 (5) May 08, 2012
This paper provides a good example of how Global Warming is ...

... a joke.

It was much colder 200,000 years ago.



-3C colder at 200,000 Years Before Present
CO2 was 130ppm lower

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