TWE Blog

Look! A frozen tsunami

Posted November 30, 2012 @ 7:16pm | by TravelWild

This photo of ice in Antarctica does look like an oncoming tsunami wave, frozen in midair, but it’s actually compressed ice.  Lacking air bubbles, the ice is so thick it’s able to absorb all red light, treating viewers to magnificent towering blues.

‘You can even see a gradation of colour within a hole poked in clean, deep snow. Near the opening, the transmitted light will be yellowish.

‘As the depth increases, the corer will pass through yellowish-green, greenish-blue and finally vivid blue. If the hole is deep enough, the colour and light disappear completely when all the light is absorbed.’

Speaking of coring a hole through ice, a US team of scientists has discovered unusual microbes at Lake Vida, on the northern McMurdo Plain.

Lake Vida, the largest of several unique lakes found in the McMurdo Dry Valleys, contains no oxygen, is acidic, is mostly frozen and possesses the highest nitrous oxide levels of any natural water body on Earth.

A briny liquid that is approximately six times saltier than seawater percolates throughout the icy environment.

Dr Cynan Ellis-Evans, from the British Antarctic Survey (BAS), who was not involved in the recent research, told BBC News: “There are various lakes that are very salty down there… but this is a really freaky one.

“It’s almost frozen solid right to the bottom. But you’ve got this brine ‘mush’ in the centre. For several years, they’ve been trying to get into it.”

He said the discovery of microbes at such low temperatures was “a very interesting discovery.”

The abundance of different chemical compounds present in the lake led the researchers to conclude that chemical reactions were taking place between the brine and the underlying iron-rich sediments, producing the nitrous oxide and molecular hydrogen.

The hydrogen, in part, may provide the energy needed to support the brine’s diverse microbial life. In addition, the slow rate of metabolism of these microbes prevents the energy reserves from being quickly depleted.

“It’s plausible that a life-supporting energy source exists solely from the chemical reaction between anoxic salt water and the rock,” said co-author Dr Christian Fritsen, also from the DRI.

If this is indeed the case, said Dr Murray, it provides “an entirely new framework for thinking of how life can be supported in cryo-ecosystems on Earth and in other icy worlds of the Universe.”

For images of the microbes, including a protrusion on some of them with an unknown function (energy transmission?) click here.

Another discovery of changes in the Antarctic waters is that marine snails are dissolving in the acidic waters. Warming creates acidic oceans; a casualty of this change is the sea butterfly, a snail whose shell is being dissolved by its newly acidic environment. This snail serves as an important niche in the marine (and human) food chain.

Numerous lab experiments have demonstrated that ocean acidification (OA) has the potential to damage marine organisms that make shells or skeletons. This paper reports the first evidence that OA is already damaging marine life in the Southern Ocean.

And not just any marine life. Marine snails are a vital part of the food web of Antarctic waters, supporting zooplankton, fish, birds, marine mammals and us. (Read Tom Philpott’s piece on the correlation between OA and human food here.)

Marine snails are also important players in the Southern Ocean’s carbon cycle—the shuttling of carbon between atmosphere and ocean. In that work they’ve mitigated a lot of our CO2 emissions. Too many for their own good, apparently.

Co-author and science cruise leader, Geraint Tarling from the British Antarctic Survey, says:

Although the upwelling sites are natural phenomena that occur throughout the Southern Ocean, instances where they bring the ‘saturation horizon’ above 200m will become more frequent as ocean acidification intensifies in the coming years. The tiny snails do not necessarily die as a result of their shells dissolving, however it may increase their vulnerability to predation and infection consequently having an impact to other parts of the food web.

As climate change continues to bring changes to our polar reaches, and science technology develops to better monitor those changes and to explain new findings, the news from Antarctica makes our planet seem smaller, more accessible, and more familiar.  A vicarious traveler’s window to this fascinating place!

 
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Filed Under: Antarctica |   | Permalink
Tags: cryo-ecosystem, Lake Vida, sea butterfly
 
 
 
 
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