My working hours are pretty evenly divided between diving with the team and running a sea spider physiology experiment in one of the Crary lab's "environmental" rooms. Environmental rooms are small sealed chambers that allow researchers and engineers to conduct experiments and tests under stable conditions. The range of abiotic variables that can be controlled typically include temperature, humidity, light, and atmospheric pressure, all of which may have influence over the behavior of the organism or material being tested.

    environmental room
    The Crary Laboratory has four environmental chambers that can vary a number of different physical conditions. This one is ours.

    I'm working with sea spiders who spend their lives in McMurdo Sound, which remains below freezing for months on end and sees only minor temperature changes over the course of a year. To keep the sea spiders happy while we vary other water chemistry characteristics and measure the animals' responses, all of the tests need to be performed in water at McMurdo Sound temperature (29F/-2C). While the Crary Lab is equipped with a flow-through sea water system through which water is pumped directly from McMurdo Sound, the water temperature fluctuates as it makes its way from the ocean through the outdoor pipes and eventually into the warm lab building. Hence, our need for an environmental room, which is kept at a brisk (29F/-2C).

    temp control
    -02C. A few degrees below freezing.

    For a few hours every other day or so, I set up, manipulate, and break down 12-hour-long runs of our experiment while standing in what is basically a walk-in freezer. The cold air itself - circulated through the room by large fans high up on one wall - is not a problem to deal with. After all, it's a couple of dozen degrees warmer than the outside temperature and I am well equipped with cold weather gear (Big Red gets worn indoors, too). The real challenge is having my bare hands in the icy water. Through most of the process of setting up our experimental apparatus, I wear big blue fisherman's gloves. However, occasionally I need the dexterity of my gloveless fingers to tighten a tiny knob, insert an optode, or perform some other precision-required task and it doesn't take very long for the water baths to draw the heat from my fingers. If I let it progress, the experience evolves from discomfort, to a stinging pain, to numbness, to loss of finger function. After the first experimental trial, I wisened up pretty quickly and now I'm quick to take breaks once my fingers start to tingle. So what's making me risk finger pain and numbness? The oxygen hypothesis for polar gigantism, of course.

    working in the cold room
    Manipulating oxygen levels in our experiment. Big Red gets some use indoors.

    Author
    Date
    Location
    McMurdo Station
    Weather Summary
    Sunny and breezy
    Temperature
    9F/-13C
    Wind Speed
    17 kts
    Wind Chill
    -18F/-28C

    Comments

    Mike Penn

    Tim, This is a cold related question. Do most of the guys grow beards while on the Ice? Aside from the water conservation and hot water issues, I can see the value of facial hair in such an extreme environment. A long time ago in some arctic Army training we were "allowed" to have facial hair...but only briefly! On the other hand I could see how it might be a problem for you to have a beard while diving. My students were just wondering. Thanks and keep up the good work and interesting journal entries! - Mike

    Michael Penn

    I just had a very knowledgable science teacher stop in to my classroom and he saw your post on my computer. He had an interesting question. How do tides affect the water pressure under the ice? How much does the Ice flex/move if at all from the tide? Also, how are the spiders moved from their natural habitat to the lab with as little impact on the animal as possible?
    Thanks! - Mike (in Pittsburgh)

    Timothy Dwyer

    Great question, Mr. Penn and class! I haven't done a formal survey but I would say that more than half of the men down here have a beard. It's
    certainly helpful when out on the sea ice and keeps the wind off your
    skin. We're issued a neck gaiter and balaclava with the rest of our
    Extreme Cold Weather gear in New Zealand before deployment, so if it
    gets really blustery, we can wear that as well. A mustache can get in
    the way while diving, making it difficult for a mask to seal on the face
    properly, allowing water in. We've got techniques for "clearing" a mask
    of water, but this generally doesn't fix a slow leak. It doesn't seem to
    be a problem for my mask, however. It's more of an issue when the
    stubble is pretty short and it seems to fix itself once the whiskers get
    longer.
    On 11/3/16 4:50 AM, PolarTREC wrote:

    Timothy Dwyer

    The short answer is Yes, tides have an influence on our diving. The 7-8ft/2.5m of ice above us rises and falls with the diurnal tide but,
    because water is mostly incompressible, the ice on top doesn't
    noticeably change the pressures we're working under. Along the shore, at
    the land-ice transition, the ice cracks a lot more with this daily
    movement and we need to be careful when walking on the ice close to
    land. Another concern is underwater currents - the tides drive moderate
    water flow in some areas nearby. We tend not to dive in these areas
    because current can theoretically make it difficult getting back to the
    entry point.

    As for the spiders, we keep them in -1.8C/29F seawater as much as
    possible. They're collected in closed collection containers, transported
    back to the lab in a water-filled igloo cooler and then kept in large
    sea tables where water is constantly pumped in from the nearby ocean.

    Great questions!
    Tim

    On 11/3/16 5:06 AM, PolarTREC wrote:

    Mike Penn

    Thanks Tim, Thanks for the response! I haven't seen the teacher who asked the question yet this morning but I'll show him your response. I think what he was asking was if the tide in a confined space (under the ice) might make the water "seem" to be deeper - as in would you need to change your air mixture - Nitrox, Heliox, Trimix? - Thanks again. This whole experience has opened up lots of interesting questions for my classes. As we often say "You don't know what you don't know!" and this has been a great opportunity to open their eyes to so much that they (and I) didn't know and hadn't thought about! - Mike

    Timothy Dwyer

    You're welcome, Mike. Antarctica is one of those places of which people have a vague image in their mind as being icy, white, and barren. While
    that's generally true, there's so much going on beneath the surface, at
    least in our little corner of the Ross Sea.

    As for the pressure question, Archimedes' principle states that the
    upward force exerted on an object immersed in liquid (its buoyancy)
    equal to the downward force (its weight) exerted on the volume of water
    it displaces. Basically, what it means is that when the sea ice forms it
    displaces some sea water, pushing it out into the Southern Ocean, and
    the forces exerted on a diver under the ice are the same as on a diver
    in open water. An interesting corollary to this is the drop in
    atmospheric pressure that occurs when diving in alpine lakes. Divers
    there have to make corrections for the drop in atmospheric pressure when
    at altitude, which does affect the amount of nitrogen being absorbed by
    body tissues at depth.

    The USAP doesn't do any mixed gas technical diving, mostly because of
    the cost of maintaining the equipment, the added layers of safety
    procedures needed, and because there's plenty of great work to be done
    at shallower depths. However, there is currently a research group
    working down here that is testing the feasibility of closed circuit
    rebreather systems in this environment. More on that later!

    Tim

    On 11/4/16 1:49 AM, PolarTREC wrote: