Casey midwinter swim 2015
Midwinter slideshow 2015
Cushion plants on Macquarie Island
Dr Dana Bergstrom
Our study has been looking at a rapid collapse of an alpine ecosystem on Macquarie Island. On the top of Macquarie Island there is a plateau and in that plateau are cushion plants that are endemic to the island, that means they only occur there and nowhere else.
What we found was rapid dieback of this endemic plant. Of 115 sites across the plateau, up to 90% of those sites had death in them in the cushion plants and up to 80% of death in mosses. This plant has been on the island for 10’s of thousands of years and so it was a really big shock.
And the first thing that we thought – is it a disease? And so after five years of study we can say what we suspect is happened is that the plants aren’t coping with recent changes to climate. They don’t have the capacity to cope with the changes that we’ve observed, which have gone from a very wet and misty environment to now one with lots and lots of drying. What happens on the Island is that a storm will come through, drop a large amount of rain, and then blow through. So the days after that are sunny and windy, and it’s that sunny and windy conditions which are putting the plants under stress.
What we are now looking at is all the plants on Macquarie Island to see how vulnerable they are to drying on the Island. So we are not just looking at the cushion plants and the mosses we are not extending it to other plants on the island to have an idea of their vulnerability to the current climate changes.
Extreme experiment under the Antarctic ice
Dr Jonny Stark – Chief Investigator
The aim of the project is to create a future ocean scenario that we might expect to see by about the end of this century. So as we’re increasing the carbon dioxide concentration in the atmosphere about 1/3 of the carbon dioxide is being absorbed by the ocean. That increase in carbon dioxide in the ocean, causes a chemical change in the ocean and basically l makes it more acidic. It’s this process which is known as ocean acidification.
So aim of this experiment was to get some idea of how Southern Ocean communities, and in particular animals living on the sea floor might respond, what sort of changes we might expect to see by the end of this century under business as usual emissions scenario, which means we keep emitting more or less what we are now.
We are expecting an atmospheric concentration of about 1000ppm. It’s currently around 400. It’s only a 0.4pH change, but it is actually a very big change in pH and would have very serious implications for a lot of marine life. For example, it can affect everything from the reproduction, to the growth and development of many marine organisms.
So we were looking at everything from the very, very small so the microbial forms of life and bacteria, up to the macro, the larger invertebrates that you find on the seabed things like starfish, sea anemones, and those sorts of things.
The experiment ran for an eight week period. The basic experimental design was specially designed chambers. So these were placed on the seabed and they were acidified to a level that we expect to see by the end of this century, so roughly 2.5 times more acidic or a 0.4 pH change.
We had four chambers in total; two of those were acidified and two of those were control. So we could compare the acidified ones and see what kind of changes might have occurred in those communities living in the chambers.
Dr Glenn Johnstone – Project Leader
Every aspect of what we did with this project was something that we’ve not really come up against before. We were modifying and inventing ways to do this and it was really gratifying when they worked. It was really great to work with a team of people and use all their different skills to try and come up with a method to make sure that this all worked.
We use dry suits, we use surface supply and AGA masks. So unlike the normal half masks that you’d be used to, this covers your entire face. It allows a space that we can have a microphone, so we have communications and earpieces, we can talk to the other diver and we can also talk to the surface.
So underneath that dry suit, we’ve got a layer of thermals, then a fleece layer and then an even thicker fleece layer. And you’re probably wearing two gloves, two pairs of socks, each person just depends is a bit different, and we have three fingered gloves – you’ve got to learn to manipulate things underwater with three fingered gloves on. A dive at the depths we were at, which was about 12–14 m, would last 50 mins. Water is always about −1.8 and under the sea ice there in that Bay it doesn’t vary over the year.
When we first got there, there was good visibility. The first dive that we did we had probably about 80–100 m worth of visibility, which is remarkable anywhere in world. Then slowly over the season that decreases when you have the algal bloom. At the end of the season it was much less than when we started but wasn’t particularly dark – it can be if you’ve got a lot of snowfall. Though we had plenty of wind, which tends to clear the snow off the ice. So even though the ice was 2.2 metres thick there was plenty of light down there.
We were visited many times by weddell seals and on one occasion in particular we were visited by one that had a fish in its mouth, which is not something any of us had ever seen before and proceeded to eat it right in front of us in the dive hole which was really special to see that.
Evacuated Antarctic expeditioner returns to Hobart
Davis station medical evacuation
Australian Antarctic Division Operations Manager - Robb Clifton
We're very pleased to report that we successfully transferred the ill patient at Davis station onto the Aurora Australis last night and that the ship sailed for Hobart shortly after the operation was complete.
Over the weekend people have been working around the clock to refuel the ship and they’ve been working in quite difficult conditions, often below minus ten degrees and with a fairly constant snowfall.
Before the transfer of the patient we did several test runs to make sure that we could do that transfer safely and efficiently and in the end it was done incredibly well by the folks in Antarctica.
The man who is a member of the station trades team, is now getting really good care and support in the ship’s medical facility, and that includes telemedicine support from specialists and others here in Hobart.
We’ve managed to actually link the patient up by phone to his family to speak to them, so that’s been comforting for them and quite important.
These events can be quite traumatic for our staff in Antarctica. Obviously our Antarctic teams are very much a small family, very close knit, so when someone becomes ill it does have an impact on everyone. I think you can see the results of that impact is how everyone has put in a massive effort in difficult conditions to get their team mate to care.
So I'm pleased to say that this massive operation went very well and the patient is now on the ship and en route to Australia.
Antarctic blue whale voyage returns
Low frequency whale sounds
Australian Antarctic Division Voyage Science Leader, Dr Mike Double:
Occasionally you sit back and go "how loud is that?", you know? It’s just incredible to think that these sounds from individual whales are travelling so far.
We covered about 15 000 kilometres on this voyage. We were deploying sonobuoys throughout, so these are the devices that listen to the low frequency sounds that blue whales produced. I think our longest detection was over 1000 kilometres, so we were hearing them at Terra Nova Bay and we were about 750 kilometres from the aggregation that we'd left. So we knew that we were detecting from 750 kilometres, but really on the way back we were still hearing that aggregation over a thousand kilometres away. We just have to pinch ourselves and remind ourselves that, you know, this is some of the loudest sounds that we hear in nature.
We actually encountered two blue whales at the Balleny Islands, but then we were hearing a lot of whales to our south-east, and when we got into that area we realised we'd found a lot of blue whales in a very small area. So in about 100 kilometres by 100 kilometres there was probably in the region of about 80 to 100 blue whales.
We could work with the whales, we could approach them, we could follow their behaviours doing video-tracking work. We took a biopsy sample.
During the day we were working with the blue whales, at night we were running krill surveys. We found some really interesting data on the krill themselves. We actually found there weren't actually… there was a lot of whales, but not a lot of krill dispersed, but when we found the krill they were in very very tight swarms. So now we're trying to understand, you know, why this habitat is particularly attractive to the blue whales.
I mean I was really surprised to see so many blue whales in such a small area. I mean, when you’re on the ship and you're on the bridge and you’ve got almost 360 degree views and you're seeing these huge blows around, around, all around the vessel, you know that was really surprising. You’re dealing with a rare endangered species and yet you’re surrounded, and like Richard said, we're becoming blasé about seeing Antarctic blue whales.
Warm ocean water melts largest glacier in East Antarctica
Dr Steve Rintoul – Voyage Science Leader
The Totten glacier has remained a secret, has remained unobserved for so long because its so difficult to get to.
We were extremely lucky on this voyage. When we left Casey and started heading to the Totten I thought it was very unlikely that we were going to be able to reach the Totten itself because we had about 100 km of heavy sea ice to traverse to get to the front of the Totten. And we were very lucky we got just the right weather conditions, just the right wind conditions that allowed us to take advantage of a crack in the ice that opened up that extended all the way to the front of the Totten.
The Totten glacier flows off Antarctica and starts to float and the floating part of the glacier is about 120 km long. Out at the front of the glacier where we made our measurements the ice is about 200 metres thick. It then gets thicker as it goes back towards the Antarctica continent and the grounding line, the place where the glacier leaves the bedrock and starts to float is 2 km below sea level.
The surface of the glacier is sinking, it’s thinning. The question is why? It could be related to the dynamics of the ice itself or it could be because the ocean is melting the glacier from below. The Aurora Australis voyage that we just completed was aimed at testing that second idea – is there any evidence that warm ocean water reaches the glacier capable of driving melt of the floating glacier?
What we found is evidence that exactly that is happening. That warm water does reach the Totten glacier. The temperatures that we measured at the front of the Totten are about 3 degrees warmer than the freezing point at the grounding line and so that’s a measure of how much heat is available to melt the ice.
We can detect melting of glacial ice a few different ways. One is just from the temperature. If we see temperatures that are minus two degrees, we know that must have happened at great depth below the floating ice shelf. That’s the only way you can produce temperatures that cold. As the glacial ice melts, it also leaves a signature in the water, that we can detect using different chemical elements and isotopes.
One of the spectacular successes of the voyage were recovery of oceanographic moorings. One year ago the US ship Nathaniel B Palmer deployed Australian and US moorings near the Totten. So we were able to recover all six of those. Those are important because it will provide a year round record of what’s happening near the Totten.
I’ve been going down south for almost 30 years now. I’ve done 15 trips, 12 of them to Antarctica and I’d have to say that this is probably the most successful trip that I’ve been part of that entire time.