The Bowman Lab

During a 2010 Arctic field effort we put days of hard work into cutting several large holes in the ice...

It’s always good to have a plan B.  When you’re doing field work it’s usually good to have plans C, D, and E as well.  Things just never go the way you think they’re going to.  Our plan A is to make it out to the ice edge to collect natural frost flowers and young (freshly formed) sea ice.  Dan finished an extensive survey toward the ice edge earlier in the week and the consensus is that the ice will have to thicken more before we can head out that way to sample.  Most of the ice in McMurdo Sound right now is between 1.1 and 1.5 m thick (4-6 ft.), with the exception of some older “multiyear” ice at the south end of the sound that is several meters thick.  Within a couple of kilometers of the ice edge the ice thickness decreases to 40-50 cm (15-20 in.).  This is, in reality, plenty thick to drive on.  McMurdo Station rules however require 76 cm (30 in.) of ice for vehicle travel.  And with no helicopters to facilitate a rescue in case of a breakthrough (they start flying in October) there is little chance of getting permission to work outside of these rules.  For access to the ice edge there is nothing to do but wait for the ice to thicken more, it won’t reach its maximum thickness until late in October.

...only to see our efforts buried under the first of an incredible series of storms.

In the meantime if we can’t reach the natural ice edge we can always try to make one that we can reach.  In this case our “edge” will be a series of large holes where ice and frost flowers can form.  We’ve tried this before in the Arctic without success; the opening salvos of a terrific series of blizzards covered the holes with snow, and then destroyed a tent that we tried to use to keep the holes snow free.  We’ve got the time now to continually maintain the holes until a calm day (and hopefully frost flowers!).  It’ll be cold, wet work but we’re ready for it!

We need 130 cm of ice to support the heavy equipment we will use to create holes in the ice. Shelly drills to check the ice thickness.

Today Shelly and I scouted around for a place on the sea ice where the snow doesn’t seem to drift too deep and the ice is thick enough for the heavy equipment we will use to drill the holes.  We think we’ve found a couple of good spots, so if the weather’s good tomorrow we’ll have a go at it…

It was a beautiful day at McMurdo today, one of the warmest we’ve had yet.  It would have been a spectacular day to be out in the field but unfortunately we had a lot of lab work to catch up on.  On Monday we collected a total of 14 sea ice cores from two different locations in McMurdo Sound.  12 of these cores we sectioned into top, middle, and bottom and set them aside to melt.  When these finally finish melting (just checked them, they still have a ways to go) we will pump the melt water through filters that will collect all of the ice algae and bacteria from the water.  Back in Seattle we will extract RNA and DNA from the bacteria and conduct our analysis.

Shelly, lost in a universe of little blue dots. Counting bacteria can be an art. Two people will count the same slide and come up with slightly different numbers. To make it easier to compare between samples and studies it is best to have one person always conduct the counts. In the Deming lab this task usually falls to Shelly, and we are grateful!

The remaining two ice cores, one from each station, we call “physical cores”.  From these cores we collect biological and physical data that helps us understand the environment that the microorganisms are living in.  This data includes the salinity and temperature of the ice, the amount of chlorophyll present (an important indicator of how much photosynthesis is going on), and the number of bacterial cells present.  To get this information we use an electrical saw in a room kept at -1 C (30 F) to cut the cores into 13 cm and 2 cm chunks (watch the fingers!).  The 2 cm chunks get melted straight away and from these we measure salinity.  The 13 cm chunks get melted (like the larger core sections for DNA and RNA) into that sterile brine that we’ve been making over the last week.  Fractions of this get filtered for chlorophyll, cell counts, and the other analyses that we’d like to perform.

Epifluorescent micrograph of a sea ice sample at 1000x magnification. The small blue dots are bacteria, the orange is organic debris. The thin blue line is a pennate diatom.

Our whole project is focused on bacteria, so the one thing that we really want to know at this point is how many bacteria are present within our samples?  To figure that out we need to take a look under a microscope, which is how Shelly spent a good part of her day.  Bacteria are very small, one millionth of a meter or smaller, so not just any old microscope will do.  In microbiology we most often use a special type of scope called an epifluorescent microscope.  Epi means the light is being projected on the slide from above, not through it from below.  Fluorescent means that the bacterial cells are being induced to give off light, or fluoresce, which makes them easier to see.  To do this you have to stain the cells with a dye.  The dye binds to DNA, and if you shine an ultraviolet light on DNA bound with the stain it will give off blue light.  This doesn’t let you see many details of the cells, for that you need an electron microscope, but it allows you to count them and see some general characteristics.

Epifluorescent micrograph at 1000x for a seawater sample.

The top photo is from sea ice.  The small regular blue dots are bacteria while the orange is organic debris.  The faint blue line in the lower right quadrant is a pennate diatom, one of the two morphological flavors of diatoms.  The other type of diatom is the centric or circular diatoms.  Most sea ice associated diatoms are pennate diatoms, so this one seems to be in the right place…

The bottom photo is from water below the sea ice.  Notice how regular the cells look and how little debris there is!  The bacteria in the two photos are probably dramatically different, but there is no way to know this looking at them under the microscope.  It will be many months, after extracting the DNA, sequencing it, and processing the data that we know any more about them!

The search and rescue Hagglan had to be dug out after the big storm.

The second round of sampling went much better today, and now we have some ice cores to work on in the lab over the next couple of days.  Things started a bit slow this morning, the storm that finally blew itself out last night left McMurdo in a bit of disarray.  Our Piston Bully was fortunately parked in a sheltered spot, but the search and rescue team’s Hagglan tracked vehicle had to be dug out before we could depart (they’ve been showing us the ropes, today was our first chance to “fly solo”).  Once on the ice things went pretty smooth.  It was still a bit breezy but nothing like the heavy winds of the last five days and we were greeted with spectacular views of Mt. Erebus on the way out of town. 

The six ice cores that we pulled from our first site, in the windbreak of Tent Island (seen in the background). In the windbreak very little snow has drifted over the ice.

We had two sampling sites picked out for collecting ice cores.  One sits in a large windbreak behind Tent Island and as a result very little snow has drifted over it, just a couple of centimeters.  The other site, about 1 km south, is outside of the windbreak.  It has about 40 centimeters (about 16 inches) of snow on it.  Snow does a couple of important things for sea ice.  First, it is a great insulator.  The top of the ice at our first site was -12C (10 F) while the top of the ice at the second site, with its insulating snow cover, was only -8 C (17.6 F).  For bacteria and algae in sea ice this difference in temperature can have a huge impact.  The warmer it is, they more they can do.

Digging out the ice at our second site. Outside of the Tent Island windbreak the snow has drifted pretty deep (Photo: Shelly Carpenter).

In addition to warmer temperatures sea ice algae and bacteria at this time of year are waiting for sunlight.  Each day brings 15-20 minutes more sunlight, though the sun is still low on the horizon and the actual amount of light that hits the ground is still quite small.  Soon, enough light will begin to penetrate the ice for algae to begin photosynthesizing.  By the Antarctic summer the bottom of the ice in McMurdo Sound will be coated with slimy green algae.  This alga is a major food source for fish, krill, and bacteria.  Sea ice bacteria in particular are thought to respond quickly to the onset of spring photosynthesis within the ice.  The ice algae give off a small amount of the carbon they fix during photosynthesis and this energy source drives the microbial response. 

Flat Stanley struggles to move a large blog of ice. Come on Stanley, you can do it! (Is it just me or does Flat Stanley look worried in this photo?)

As you might guess the amount of light that gets through 40 cm of snow cover is much less than that which gets through 5 cm.  So the biological community at site 2 is a little bit warmer, but also has a little less light for photosynthesis than site 1.  Hopefully today’s samples will help us understand how the community responds to this.  Snowfall patterns at high latitudes are changing dramatically, and Arctic sea ice in particular is thought to be accumulating more snow.  If the algae and bacteria in sea ice begin responding to sunlight later in the spring this could have an interesting impact on the rest of the ecosystem.

A blustery day at McMurdo Station.

Well, we were hoping for another chance at the sea ice yesterday but a storm came in and kept us confined to McMurdo Station.  The winds continued through the night, and have really picked up in intensity today after a brief lull this morning.  We are getting frequent gusts to 50 knots (93 kph/58 mph) and from the feel of things occasionally higher than that.  If it was just windy this wouldn’t be so bad, but the dry icy snow around McMurdo feels like sand.  Walking from building to building is not so much like being in a blizzard as being in a sandstorm.  Conditions are even worse out on the flat sea ice.  Visibility out there would be just a few feet.  So it’s a good day to stay inside and catch up on other work.

We took the opportunity to have a meeting with some of the safety personnel and the station manager about how we will operate when conditions improve.  No one has worked as far from the station this early in the season as we hope to do, and we have to alleviate a lot of their concerns to be allowed to do this.  After going over plans for safe travel to the ice edge, possible locations for a shelter between the ice edge and McMurdo, and our procedures for managing incidents at the ice edge we are closer to getting a stamp of approval but we aren’t there yet.  Once the weather clears we will spend a few more days on the sea ice around the Dellbridge Islands and working with Dan and Jen to set a safe route to the ice edge near Cape Royds.  Once that’s done we should be able to do some science!

In the meantime we have one major task that we are slowly making progress on; making and sterilizing around two thousand liters of very salty water.  This is definitely not a trivial process, but without it we simply couldn’t process our samples.  This is a result of the way sea ice forms and the way bacteria and ice algae (and viruses and anything else biological) lives within sea ice.  Seawater starts to turn into ice at about -1.8 C, but although it might look solid below this temperature it actually consists of two portions, relatively fresh ice crystals and salty liquid water.  The crystals give the ice its structure, and the colder it gets the larger they get (and the smaller the liquid fraction gets).  The crystals however, don’t hold onto the salt in seawater when they form.  They reject it into the remaining liquid fraction.  So the colder the sea ice gets, the smaller the pockets of liquid water get, and the saltier the water in those pockets becomes.

Microscope images of the pore spaces within sea ice (left), and a sea ice diatom living within one of these pore spaces (right). The liquid around the diatom is very saline relative to seawater, while the crystals have a very low salinity. Image from Krembs et al., 2002.

Bacteria, algae, and everything else that isn’t pure water are forced into those pockets along with the salt.  Because of this bacteria in cold sea ice are living in a very salty environment.  Bacteria (like any cell) must reach an osmotic balance with this salty environment.  There are a variety of mechanisms for doing this that I’ll talk about in a later post.  The end result however, is that if you take these bacteria from their salty environment and place them in fresh water they will suddenly take in a lot of water and pop!  Directly melting a chunk of sea ice does exactly this.  The bacteria might be living at a salinity of 150 ppt (parts per thousand), about five times the salinity of the ocean.  The melted ice might have a salinity of only 10 ppt.  So to keep the cells in sea ice from lysing (a fancy word for bursting) we have to melt the ice into water that is very, very salty.  That way the final melt is a mix of relatively fresh seawater and very salty brine and approximates the salinity of the liquid in which the bacteria live.  So Shelly and I have around 420 kgs (925 lbs) of salt that we need to transform into saltwater, filter to make clean, ultrafilter to make sterile, and store somewhere…

Returning from Cape Barne. You can see Mt. Erebus in the background (right) and Tent Island.

We’ve had a busy couple of days getting geared up to start some field work. On Monday we took a long trip out on the sea ice with Dan, a New Zealander who works for the USAP and has long experience with the sea ice in McMurdo Sound.  Two years ago Dan was involved with a New Zealand research program out of nearby Scott Base that conducted an extremely challenging series of sea ice observations throughout the winter, something that had never been done before (almost all science programs shut down for the winter in Antarctica).  It was slow going, we were moving over sea ice that hadn’t been traveled on yet this season which meant lots of scouting and drilling to make sure the ice was thick enough.  We made it to Cape Barne, just a few kilometers south of Cape Royds, which is traveling pretty far from McMurdo for this time of year.  From where we stopped we could just make out the ice edge where we will be conducting most of our work in the weeks ahead. 

Without hunting and land predators Antarctic seals are a pretty docile bunch. Rules state that they can be approached so long as they don't react. This one decided to take a look at us, so time to back off...

Most of the ice surface looks like a desert, flat and devoid of any obvious life (in contrast to the marine waters underneath).  When we get close to any crack in the ice however, we are likely to find some seals lying about.  One of the most amazing things about the wildlife in Antarctica is the lack of any response to approaching humans.  These seals aren’t hunted and there are no land predators to threaten them.  On the ice they are quite relaxed and easy to approach.  The rules for interacting with wildlife in Antarctica allow you to approach so long as the animal isn’t responding to your presence. 

Shelly clears snow off the ice so we can take some ice cores. The long red tube that I'm holding is our soon to malfunction corer. On a successful day we fill the blue barrels with ice for transport back to our lab at McMurdo. Tent Island can be seen in the background.

We were back out today with Jen to conduct our first sampling and give our gear a shakedown.  Jen is another USAP guide with a lot of sea ice experience.  The first sampling effort of a field campaign never goes well, and this was no exception!  The motor to power our coring equipment wouldn’t start, and our backup motor was missing critical pieces.  More importantly we had been issued a beautiful, brand-new sea ice corer to use with these motors, but an essential piece of the corer was packed in factory-grease and totally unusable in the cold!  After several hours of struggling with gear we called it quits and headed back to McMurdo.  Just a couple of kilometers from the station the wind came up so strong that we could only identify our outgoing tracks on foot.  So Shelly and I bundled up, and with Jen driving behind us we were able to (with only a couple errors) retrace our steps.  We made it back just in time to switch out our inoperable gear for a fresh effort tomorrow, if the weather is better!

At the suggestion of a colleague we’ve integrated the blog with Facebook to make things easier for those of you who are avid Facebook users. You can “like” individual posts, or if you “like” the Facebook page “The Deming Ecosystem in Antarctica” you will automatically get each new blog post on your wall, or so I’m told. This might also be a great way for different classrooms or schools to interact, if there is interest.

Mt. Discovery, across McMurdo Sound from the Station.

We have a beautiful view out the window in our lab. The sun never rises very high on the horizon, so for much of the day everything has a nice pink or orange hue. Looking to the south we can see the McMurdo Ice Shelf in the distance. Directly across from us are Mt. Discovery and Brown Peninsula, and north of them is the majestic looking Royal Society Range. Behind Mt. Discovery and the RS Range are the McMurdo Dry Valleys, a bizarre polar desert that we plan to visit in 5 or 6 weeks. One thing that strikes us every single day is how similar Mt. Discovery looks to Mt. Rainier, an emblematic mountain outside of Seattle.

Mt. Rainier, in the state of Washington.

Although not as famous as its neighbor Mt. Saint Helens, which erupted catastrophically in 1980, Mt. Rainier is an active volcano. Its distinctive shape is typical of stratovolcanoes, a special type of volcano characterized by highly viscous lavas (and very explosive eruptions). This high viscosity does not allow the lava to flow in the manner of the volcanoes of the South Pacific, termed shield volcanoes. As a result the sides of the volcano build up over time and can become quite steep. So is Mt. Discovery also a stratovolcano?

I don’t know a whole lot about volcanoes so I did a little looking around today while Shelly kept things moving along in the lab. As with many geological features in Antarctica I could only find a little public information online. A short blurb on the Oregon State University website notes that Mt. Discovery, like the more famous and active nearby volcano Mt. Erebus, is on a rift system that splits the continent. This explains why there are volcanoes near McMurdo, but doesn’t tell us much about type. Along a rift in Iceland stratovolcanoes and shield volcanoes exist side by side. I did find an article by a Japanese geologist in 1972 indicating that the McMurdo area volcanoes are typically composed of olivine-basalts and the minerals trachyte, kenyte, and phonolite. Olivine-basalt sounds suspiciously like a shield volcano. I wasn’t familiar with the other minerals but when I looked them up I found that they are silicate rich (as opposed to iron rich, like olivine), a clear mark of a stratovolcano. It’s the silicate nature of stratovolcano lava that results in high viscosity and explosive eruptions.

After a bit more searching I finally found what I needed, a 1975 article (this one isn’t free, but let me know if you’d like a copy for education purposes) detailing the composition of Mt. Discovery lavas. They match the general pattern for Ross Island, so it looks like appearances were a good indication. We have a stratovolcano!

Tomorrow Shelly, Flat Stanley, and I head out for some further training on the sea ice, hopefully the last piece before we can begin work. This training will be the first chance we’ve had to really get away from McMurdo Station and into the environment we came to study, so we are quite excited!

McMurdo at night, with Discovery Hut in the foreground. The large rise behind the station is Observation Hill.

Last night after dinner Shelly and I took a walk out to Discovery Hut, a famous landmark just a few hundred meters north of McMurdo Station.  Discovery Hut is a relic of the 1901-1904 British expedition led by Robert Scott, one of the earliest land explorations of the Antarctic continent.  The interior of the hut (and of several other historic huts on Ross Island) is designated as a Specially Protected Area so were weren’t able to enter, though we may have an opportunity later in the season.  Because of the cold, dry climate and stout construction the hut has weathered the 100+ years well. 

Visiting the hut provides a nice touchstone to the long history of science on Ross Island.  Some of the early expeditions, in particular the British expeditions, were extremely dedicated to science.  Robert Scott and his polar party refused to jettison heavy geologic samples during their long and ill-fated return from the south pole in 1911.  An even more extreme example of scientific dedication from the same expedition occurred several months earlier.  In the middle of the Antarctic winter three of Scott’s men undertook one of the most spectacular polar journeys on record, all in the name of science (and maybe a little bit for the adventure).  They journeyed from the relative comfort of the expedition’s base camp at Cape Evans, south around Ross Island, to the wintering ground of the Emperor Penguins at Cape Crozier for the sole purpose of collecting penguin eggs.  At the time it was thought that penguin eggs might yield interesting information on the process of speciation, a concept only recent introduced by Darwin.  In an incredible display of endurance the party survived the weeks of storms, darkness, and temperatures to -77 F (without wind chill) and succeeded in collecting a handful of eggs (to learn more check out the phenomenal autobiographical account by Apsley Cherry-Garrard titled The Worst Journey in the World).  The abandoned Discovery Hut was the first refuge the party reached on their return from the Cape, and their first night of safety and comfort in many weeks.

Those of us who choose to study the polar regions today have things a lot easier, but there are still many frustrations and discomforts.  The logistics are complicated, fingers and toes freeze, we get tired after long days of sampling.  Visiting Discovery Hut and other monuments to scientific history are a great way to put these things in perspective and make them seem a lot more tolerable.  With that in mind we waited out another canceled cargo flight and spent a relaxing day today sorting out the field gear that we will need in the coming weeks.  The weather has been calm and clear all day, so the rest of our supplies should make it in in just a few hours…

Category II as seen from the Crary Lab. The McMurdo operations center can be seen in the background.

Since we arrived the weather at McMurdo has been unseasonably warm.  As I’m writing this the outside temperature is -10 C (14 F) with no wind, balmy for this far south!  Normal daily max temperatures for this time of year are still below -20 C.  Warm temperatures in Antarctica are usually associated with storms and wind, and despite the calm conditions right now that’s definitely been the case! 

Flat Stanley heads out into the storm. There were some concerns about Flat Stanley's clothing selection for Antarctica, so Shelly helped him out by knitting him a scarf.

The weather at McMurdo Station is described as either Condition I, II, or III.  Condition III is normal, with winds below 48 knots (still pretty brisk), visbility above 1/4 mile, and a wind chill above -75 C.  Yesterday we had our first Condition II day, with blowing snow reducing visibility for a sustained period of time.  We are still allowed to work under these conditions, but we aren’t allowed to leave the area for recreation.  A section of road between McMurdo and the ice runway reached Condition I today, under those conditions you aren’t allowed to leave the building you’re in!  Anyone driving on the road would have had to stop and wait it out until conditions improved.

Shelly passes the Piston Bully training with flying colors!

Shelly and I are slowly moving through the training and lab setup needed before we can start traveling on the ice and doing science.  The wind has held up the cargo flights that will bring in the rest of our gear, but hopefully some of it will make it in tomorrow.  In the meantime we got checked off to drive the Piston Bully, a tracked vehicle that will serve as our means of transport to and from the ice edge in the coming weeks.  In the Arctic we’ve always relied on snowmobiles, which are faster and a little more maneuverable in broken ice.  On the flatter and windier ice of McMurdo Sound the Piston Bully’s, with their heated cabs, are the preferred mode of travel.  They are pretty fun to drive, but a little slow if you’re used to a snowmobile…