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Impacts of the Larsen Ice Shelf System on the Weddell Sea

Hello Amber! I have been following your journals and it looks like you are experiencing a ton of cool science! I was teaching during your Polar Connect event, but just watched and listened to the recording. Please thank all the scientists who presented with you, as it was a great display of the diversity of polar science happening all on one ship. I have been teaching about bacteria and we were just talking about chemoautotrophs and anaerobic bacteria the other day. I can't wait to show my students your live event.

I do have some questions for the Bacteria folks. How long can the anaerobic bacteria survive in an O2 rich environment? When you pull them up, what is the time frame between pull up and putting them into the box? How do they know which ones to put in the box or do they all go in there?

Have a great last two weeks!

Melissa Barker PolarTREC Toolik May 2012

Thu, 04/12/2012 - 14:12

Amber Lancaster

Hey Melissa,Thanks for following along! There's two different processes the
scientists use based on how they are collecting sediment.
Kasten cores are long, square, metal tubes that don't easily fit into
the glove box where the anoxic work is done. Because of that, the
scientists sample DNA as soon as the core is opened using cut off
syringes to collect sediment. From there, the DNA is frozen so that it
won't be denatured. Kasten cores take about 30 minutes to get from the
deck into the lab, but there's not an appreciable exchange of gases with
the atmosphere as long as the core is closed.
Megacores are slightly different. These are only a meter long and the
scientists have a contraption that allows them to sample the mud inside
the glove box. Basically the mud is pushed up like a push pop through
the tube. The tubes from a megacore are quickly capped and they try to
prevent as much oxygen from entering the tubes as possible. From there,
the tubes are kept in cold rooms (4 C) covered in foil which prevents
their exposure to light, which could possibly change the geochemistry of
the environment. Ideally, the tubes of mud would go straight into the
anoxic box, but sometimes they are working on other projects. The tubes
are always processed within 24 hours.
If the scientists are sampling specifically for anaerobic bacteria, it
has to go into the glove box to be processed.
Hope that helps! There are pictures of the Kasten core and the megacore
on the website and in the ppt of the PolarConnect event. Let me know if
you have any more questions.
Amber

Wed, 04/18/2012 - 11:41

Anonymous

Thanks so much Amber! My kids were very interested in learning about these techniques of sampling.Melissa

Fri, 04/20/2012 - 06:42

Amber Lancaster

Hey Melissa,One thing to remind them about is that the sides of the cores are always
contaminated because they are smeared as they move up the side of the
tube. For that reasons, samples always have to happen in the center of
the core. Otherwise, the sediment might not actually come from a
particular depth.