It has been a dark year under the ice. Heavy snow has made very little light shine through to the depths. However, the scenery is no less spectacular. Here is a short clip showing what a “normal” dive looks like for us.
A short blog with a little more info about our arrival in Antarctica two weeks ago.
The plane landed safely on the ice! When the crew opened the rear hatch, we were immediately hit with a wave of icy cold air. Exiting the C17 aircraft is always really exciting as everyone is eager to get their first ever (or first of this season) glimpse of the icy continent. Once we disembark, we are quickly ushered along towards the transport vehicles that will be driving us to McMurdo Town.
Here is a compilation of some videos I took during this journey:
One of the main research questions we have focuses on the research site known as Cinder Cones. This is an area where methane leaks from the seafloor and is harvested by microbes for energy. Over the last 10 years the obvious microbial communities have been slowly replaced by dense beds of sand anemones (Edwarsia). This is what it looks like this year – tons and tons of them everywhere.
There are also tons of the star fish that seem to have come into this region. More on that in a future post, but there appears to be an interesting relationship between the stars and what the seep is doing to the ecosystem.
You can still see the small areas of microbial mats being present but they are far more reduced than previous years. However our research is showing that there is still a lot of methane being released. In the image above you can see the small patches of white which are indicative of where methane is seeping from the seafloor.
This area has become a real interesting and yet perplexing place to research, but like all good research sites – it keeps surprising us with its novelty and unexpected patterns. This all lets us better understand how the greenhouse gas methane is kept out of the atmosphere, one microbe at a time.
Ice is as far as the eye can see in Antarctica. It varies in age from million-year-old ice sheets that are miles thick, to annual sea ice that is measured in meters. One incredible form of ice in Antarctica is anchor ice, which resides on the seafloor down to a maximum of 90 feet deep. Anchor ice typically forms plate-like crystals that overlap each other to form jagged structures on the seafloor that are resoundingly beautiful.
Ice and life come to a head in the McMurdo sound. As the anchor ice takes hold, it covers the seafloor and the animals residing on it. This makes for an odd life for the animals subject to the freeze and changes the ecology of the seafloor. Because ice has a lower density than water, Anchor ice can actually pick up the organisms it freezes around and float them to the sea ice ceiling, incorporating them and causing them to eventually die.
An example of a seafloor brimming with both life and anchor ice
With that said, the combination of life mingling with ice is amazing to witness. Most evidence points to anchor ice as damaging to many species, but I have to wonder: In all this time of life and ice intertwined, are there adaptations to life in anchor ice? Are there organisms and ecosystems that require anchor ice?
The sponge Homaxinella Balfourensis encased in anchor ice. Anchor ice can almost entirely eliminate this species from an area, evident to researchers by discolored sponge skeletons.
The sea urchin Sterechinus neumayeri, which sits on top of an anchor ice field. S. neumayeri is numerous in the shallows of McMurdo sound, causing it to inevitably live within and around anchor ice. This sea urchin is largely a grazer, living off of algae, diatoms and animals such as sponges. One interesting fact about S. neumayeri is that it co-opts items from the environment for camouflage! You’ll typically see these urchins with pieces of shells and other objects on their spines.
A fish of the Trematomus genus. These fish often have antifreeze compounds that bind to ice forming in their blood. This is a great example of animal adaptation to living at extreme cold conditions.
During a dive at Cinder Cones last week, Amy and I got to watch an incredible battle between two male Weddell seals underwater.
I was originally just filming Amy framed with a beautiful crack in the sea ice behind her, but then, out of the shadows, two giant seals started making a bee-line for her!
Luckily the camera was still rolling and therefore I caught the scuffle on camera! Check it out:
Weddell seals (Leptonychotes weddellii) live farther south than any other mammal. They grow between 2.5 and 3.5 meters long, and adults can weigh between 400-600 kg. They persist on a diet of fish, crustaceans, krill, squid, prawns, cephalopods, penguins, and even other seals!
Weddell Seals can stay underwater for up to 80 minutes at a time and have been documented to dive over 600 meters deep. These long dives are for both foraging and for finding new breathing holes in the ice above.
I just love watching them on a dive!
On our journey across the Southern Ocean, we flew directly over the Drygalski Ice Tongue!
An ice tongue forms when a glacier that is confined by a valley moves very rapidly out into a lake or (in this case) ocean, relative to other ice along the coastline. The ice tongue is actually a part of a glacier that is floating on the ocean.
When an ice tongue surges past adjacent coastal ice, the boundary experiences physical forces described as “shearing”. Look for the sheared, zig-zag edge of the Drygalski ice tongue in the timelapse video below.
Here are some amazing facts about the Drygalski Ice Tongue:
- It is the largest ice tongue in the world!
- It reaches 70 kilometers (43 miles) out to sea from the David Glacier
- It ranges from 14 to 24 kilometers (9 to 15 miles) wide
- It is thought to be at least 4,000 years old
- The David Glacier grounding line, where the ice leaves the shore and begins to float, is in a depth of ~1,900 m (6,200 ft)
- In 2016 a 30 km (19 mi) long section of the ice shelf calved to form two large icebergs
This past week, I’ve had the incredible opportunity to slip through the cold and dark portal into what can only be described as an alien realm. Sitting above the dive hole made my eyes widen and my heart pound. I had seen pictures, sure. But was I really up to the task of diving under sea ice? After a brief wave to Michael on the surface, I took the plunge.
The first time going through a dive hole is a strange experience. From above, you would think it would be cramped or claustrophobic sinking through 8 feet of ice. Once in the hole, however, it was an entirely different perspective. The visibility is so incredible in Antarctica that once your face is in the water, you can easily see the incredible wealth of life on the seafloor. Curiosity got the better of me, and I opened my drysuit valve to descend.
After a brief moment of pure white, I descended through the hole and the under-ice world opened up to me. Fine shards of brash ice hung from the ceiling, breaking and dancing with my air bubbles. The snowpack above made for incredibly dark yet beautiful conditions, lit only by the ambient blue of a crack in the ice above.
Brash ice is fine shards of ice crystals on the underside of sea ice
My tentative thoughts were immediately washed away by questions. The floor was covered in life!!! I knew this conceptually, but to see it with my own eyes was incredible. I looked down and thought all the five W’s: Who’s down there? What adaptations are needed to live in such a unique environment? When in Earth’s history did life become so special in Antarctic waters? Where does the anchor ice stop on the sea floor? Why does life thrive in such cold water?
I couldn’t believe my eyes!!! The sea floor was abundant in life!!
Unfortunately, humans are not amphibious, and my time was limited by the air in my scuba tank. I came to the surface and was helped out of the dive hole by Andrew. From that moment and every dive since, I have a stronger and stronger desire to jump back in the hole and witness the incredible life of Antarctica.
Andrew swimming up the dive hole and leaving the under-ice realm
By Michael Rodriguez
By now, Jacob is a seasoned Antarctic diver. But just a week ago, he completed his first Antarctic dive. He was accompanied by Steve Rupp, a dive supervisor here at McMurdo. Steve is wearing the black and white dive suit. Steve is a highly experienced and skilled diver, having done about 1500 dives in Antarctica alone. And he is a heck of a nice person too.
The dive took place from a heated hut, the yellow structure, positioned over a dive hole.
One of our main research sites is called Cinder Cones. It is an area where methane is actively being released from the seafloor and we really want to know who eats it so it stays out of the atmosphere. Its microbes… but which ones!? But step one? Getting a dive site there.
This starts with heading out on the ice, using all of our trainings (both new and old) to make sure we stay safe. Today we were accompanied by Mitch, the person in charge of Sea Ice Safety, as well as a Cadre of people to get to the site and knock out a dive. This is a challenge in itself, but step one is getting to the site.
The sea ice is thick this year (2m/6ft or so at least) but there are still cracks and we need to make sure that they are both thick enough and wide enough for our vehicles (designed to cross cracks) to cross. Our Piston Bully (the red vehicle shown at the top) can cross cold ice that is >30cm thick and areas less thick than that as long as the gap is <91 cm. We are trained (and have an expert along to help) to make sure we are always on ice that is much better than this limit. The challenge is actually recognizing a crack sometimes and also, sometimes cracks can be larger than that. Above is a photo of the crack that turned a 5 hour day into an 8+ hour day. It is too wide and thin to cross, but also completely covered by snow. To measure thickness we have to dig it out and then drill down to see how thick it is. And we (and by we I mean mostly Michael and Jacob) something on the order of 25+ times.
We eventually found a crossing point that was nice and thick and narrow but it took us an additional 15 miles out of our way. And Piston Bully’s look cool and are great, but fast they are not. I expected to get to our dive site around 11am or so but we got there at 3:30 pm instead.
Most of this was spent digging and drilling. But the day was fine and the weather balmy (for Antarctica).
As an added advantage, I got to go to a part of the bay that I had never been before and as always, the views were just constantly beautiful and ever changing. Ice and rock, in constant battle and contrast.
In the end, we decided to postpone the dive until tomorrow. But we have a hut, a hole, and a safe route. Who could ask for anything more? Huge thanks to Mitch, Eric (the driller) and two people from the Carpenter Shop who spent the day with us to support our science.
It is wonderful to be back in Antarctica after a year away. New colleagues, faces, and a reintroduction to the amazing ice above water. After a slough of trainings we also began to dive again under the ice. The first trip under was the three of us that have dove here before. We still do the same briefing and checkout dive as everyone else, but are used to the immediate shock of the cold… followed by the shock of the amazing animals underwater.
Every year is amazingly different in a place where many of the animals live decades if not centuries. This year I was incredibly surprised to see soo much of this sponge (the upright bush looking thing) are one of our most frequented sites “The Jetty”, named after it being right next to the jetty where the water intake pipes for the station sit (those pipes bring in salt water for us to desalinate and drink, as well as pumping nice and cold, fresh seawater into the aquarium room). This sponge is one that grows quickly and then poof is all gone, but the bushes were dense this year!
The other difference is that there is a bunch of snow on the ice, making it very dark underneath. Last year it was pretty dark, this year it is DARK. A really interesting fact is that the ice thickness doesn’t really impact the amount of light, but it is all how much snow is on the top. I have dove with 18ft/6m of ice over my head and it is bright as an overcast day, and under 3 ft of ice with a bit of snow on it and it is the darkest night.
But the diversity that lives here remains to astound me with each foray under the frozen ocean surface. It is good to be back underwater and in the most amazing, if not warmest, place on the planet.