Ship Relief

It has been a busy time on base these past few days. We have a big ship in port, called the James Clark Ross.

 

This ship brings in relief supplies for the base, including loads of food, barrels of fuel, and science equipment. It’s the main way that most cargo gets to base from the UK, since the planes can’t carry a lot at once.

Unloading all the cargo is a big job! There is now constant traffic of cranes and tractors moving cargo containers around base, and most people have been pulled away from their regular duties to help. 

The wharf is busy with unloading the ship ("ship relief", as it's called), so we can’t use the small boats to get to our remaining field site. Since we can’t do our sampling, we pitch in to help unload. Over the past couple of days, I have moved a LOT of food from the shipping containers into the storage rooms and freezers around base. It has been quite a workout for my arm muscles!

Hopefully, the ship will be unloaded and away from the wharf on Wednesday, so that we can get to our final field site.

What we can learn from the Larsen Ice Shelf

The Larsen Ice Shelf is a huge piece of ice that sits on the other side of the Antarctic Peninsula from Rothera Station. It is divided into sections, which are named, from north to south (left to right, in the map), the Larsen A, B, and C.

Back in 2002, a large piece of the Larsen B broke off into the ocean. The piece that broke off was 1,250 square miles, about the size of Rhode Island! It broke apart and fell into the ocean over a course of about a month. (You can see the satellite images of its breakup on NASA’s website.) The loss of the Larsen B was a huge event, because it was the loss of a LOT of ice over a relatively short period of time.

Satellite image of the Larsen B breakup from NASA's website

The Larsen B section of ice was mostly covering the ocean (but connected to ice on the land). Because it was already floating, the amount of water in the ice did not add new water to the ocean when it broke off. That means it did not cause any rise in overall sea level. Think about it… When the ice melts in your glass of water, the glass doesn’t get more full of water. That’s because the ice was already taking up space while it was a frozen cube. Whether the water in the glass is frozen or liquid, it’s still part of the overall level of water in the glass, so when it melts, the water level doesn’t change. But, if you add new ice cubes to your glass, the water level would rise because you added more water (frozen water) that wasn’t already there. The remaining ice on the Larsen Ice Shelf is “grounded ice”, meaning it covers land, not water. If it breaks off, it would add new water to the ocean and cause sea level rise.

Many of the scientists working from Rothera Station study the Larsen Ice Shelf. Some of them study why the Larsen B section broke off. (Scientists think it was caused by higher temperatures creating many pools of meltwater on the surface. The meltwater leaks into cracks and crevasses in the ice, to then act like wedges that deepen the cracks and break the ice into pieces.) The scientists I met study what that break-off means for the ice that remains. Is the remaining ice less stable now that it’s lost a huge chunk of itself? They have put GPS stations around the ice so that they can track the speed of its movement. It’s important to know if the rest of the Larsen Ice Shelf is stable, because its breaking would contribute to sea level rise.

I also met scientists who study what that loss of ice means for the rock and earth beneath the section that broke off. Ice is very heavy and can actually squash the rock and earth beneath it. We don’t usually think of rock and being squishy enough to be mashed down by ice, but the ice is that heavy! It can squash rock! When large pieces of ice disappear, the rock beneath it can re-expand now that the weight is no longer pushing it down. (Think about pushing down on a sponge with your hand. When you remove your hand, the sponge re-expands.) That happens pretty quickly after the ice is gone. Even after that re-expansion, the ground will continue expanding because the magma in the mantle is able to flow back in to the crust to keep pushing up on the earth. (Think again about pushing down on a sponge with your hand, but think about pushing it down in a bowl of water. When you move your hand, it would not only re-expand because the weight of your hand is gone, but it would also start to soak up water to expand even bigger.) Scientists are using radar and GPS to measure that ground expansion after the Larsen B fell off. Most of the expansion they’ve measured so far is actually from the mantle flowing back in, which surprised them, because they expected that part would happens much more slowly.

The Larsen B receives a lot of attention, but it was not the first or last of the ice shelves to break apart. There have been many other examples of major ice shelves breaking up over recent years, including the Wilkins Ice Shelf. Loss of ice is expected to continue of warming continues in this area.

Holiday Field Work

Christmas was very festive here at Rothera Station. One Christmas Eve, everyone on station gathered together after dinner to sing carols, drink mulled cider, and eat mince pies and other holiday goodies. Christmas Day was a day off for most people. Uffe and I did a bit of work in the lab before the big Christmas dinner. The chefs put together an excellent five-course meal using REAL fresh vegetables, complete with traditional British krackers and Christmas pudding.

Boxing Day (the day after Christmas) was also a day off for most people, but some of us went to our next field site on Jenny Island.

Jenny Island has not been visited very often, because it is outside the typical boating range in uncharted waters. (We were able to go because there's a large vessel in the area that would've rescued us in an emergency.) It was fun for us to be able to go! As it turns out, Jenny Island was an excellent place to sample soil. We found very large beds of moss and grass that provided great soil samples. You can see some of the moss bed in the picture above. We got a lot of great samples, which we are now processing in the lab.

There are a lot of elephant seals on Jenny Island. This one was very curious about our boat and kept shoving it. Elephant seals can weigh a couple tons, so they are quite capable of swamping the boat! One person always had to stay near the boats to shoo them away if they caused a problem, which made this elephant seal very unhappy!

Marine biology

There are a lot of neat creatures living in the ocean around Antarctica: not just whales, seals, and penguins! There’s quite a diversity of invertebrates (animals without backbones) living on the ocean floor. We call these benthic invertebrates. (“Benthic” means they live on the bottom.)

There are several scientists at Rothera who study these benthic invertebrates, and they shared some of their animals with me. There are some animals you are probably familiar with: sea stars (or starfish), brittle stars, sea cucumbers, and anemone. There are also other really neat animals that you may not know, like feather stars, sun stars (big sea stars with lots of arms), sea lemons (a type of snail), and nudibranchs (a type of mollusk). You can see many of these animals in these pictures I took from the marine water tanks in the lab.

Sun star with a feather star in the background

Sea star, with a sea cucumber to the right

Sea lemon, sea star, and brittle star

Nudibranch

Terri, one of the marine biologists, tells me that they’ve learned that these benthic invertebrates are less abundant in the water here than they used to be. With the increasing temperatures from climate change, there is less ice over the water. Specifically, the “fast sea ice” is declining. Fast ice is the ice that’s thick and fastened to land, so it doesn’t float or drift around. It holds everything floating on the water in place, including icebergs. Fast sea ice used to cover the ocean for around 8 months of the year. Now, because it’s warmer, the fast sea ice is only around for 2 months of the year. Without the fast ice, ice bergs can float around and move more than they used to. The bottoms of ice bergs are very deep and, here along the coast, they scrape the bottom of the ocean. The benthic invertebrates at the bottom of the ocean can’t run away from the ice bergs. Because most of them have soft bodies without shells, and get smashed by the moving ice bergs. That is one of the many changes this region is experiencing due to climate change!

Is there soil in Antarctica?

Most of the scientists that work from Rothera Station study either ice or the ocean. There are not many soil scientists. One of the questions we get asked a lot is, “There’s soil here?” Yes, there’s soil in Antarctica!

Soil is formed from the weathering of rock, which breaks it down into small particles. Those small particles get colonized by biology. In Antarctica, it’s easy to see that rock gets weathered by the wind. There are also organisms living here, so that means we have soil! Many people don’t think it’s soil, because it looks more like sand to them. The soil at home has more noticeable plants and decomposition happening. But in Antarctica we have lichen and moss growing on the soil, and a lot of microscopic organisms in the soil. Bacteria, fungi, nematodes, Tardigrades, and other microscopic invertebrates live here, so there’s biology even if you can’t see it without a microscope!

 This photo captures the formation of soil in Antarctica. It starts off in the crevices of rocks, for example. The biology turns that weathered material into soil, and over time it can build up and turn into a larger expanse of soil like we see at Mars Oasis.

Next field site: Anchorage Island

Yesterday we took a boat out to our next field site at Anchorage Island, which is an island near Rothera Station. So it is the farthest north of the sites we've sampled so far.

We collected soil in the same way we collected from our previous sites, by taking replicate soil samples from beneath different above-ground growth types. In addition to moss and algae, we were able to take soil from beneath grass. The reason Anchorage Island is interesting is because it's one of the most southern sites along the Antarctic Peninsula where you can find grass.

There's only one species of grass in Antarctica, and it mainly only grows in the more northern, less cold areas. The species of grass is Deschampsia antarctica, commonly known as Antarctic hairgrass. Here's what the grass looks like at Anchorage Island. Until recently, it was covered with snow, so it's still mostly brown, but soon it will perk up and turn green!

I think sampling the islands is fun, because we get to take a boat out on Marguerite Bay. Here's what it looks like riding back to Rothera Station from Anchorage Island on the boat:

Lab Work

Now that we’ve collected soil samples, we need to extract and identify the organisms living in the soil. We also need to measure the chemistry of the soil to understand the organisms’ habitat. For the past few days, we’ve been working quite a lot in the lab.

We first preserve part of the soil to measure the bacteria and fungi back at home in the U.S. We separate some of the soil into a vial and add a solution that preserves the bacteria and fungi. These vials will be sent home and analyzed there. We will use microscopes to count the number of bacterial and fungal cells in each sample, and we will find out what species they are using their DNA.

From another portion of soil, we extract the nematodes that live in the water around the soil particles. This is done by wrapping the soil in a tissue and placing it on a rack that’s submerged in water. The nematodes float out of the soil into the water, then drop to the bottom of the dish. We’ll collect the nematodes from the bottom of the dish and look at them under a microscope to identify them. Other animals also live in the water around soil particles, such as Tardigrades and rotifers, which we may find in these samples.

We also extract larger invertebrates from the soil. These are removed from the soil using two methods. One of the methods uses heat created by a light bulb. We place soil or moss on a funnel and attach a light bulb. (You can buy official versions, but we made our own out of drink cans, gauze, and Christmas lights!) We gradually turn up the dimmer switch over a few days, which heats and dries the soil. The organisms try to move deeper in the soil to stay cool, which makes them fall down through the funnel into our vial. So far, we have found a lot of mites and springtails in these samples.

We also plan to measure the chemistry of the soil. We want to know how much nutrients are available in the soil (like nitrogen, phosphorus, and carbon). We want to know the pH of the soil and how salty it is. All of these are important for the organisms living in the soil. If it’s too salty, too acidic, or if nutrients are too low, they may not be able to survive. We expect to find that the different types of growth on the soil (moss, lichen, algae, etc.) house different communities of organisms because they create different soil chemistry.