This week at Davis: 11 December 2015
This week Davis expeditioners welcome an old friend: a tagged male elephant seal. Science and field training rule, and the new Davis band has everyone dancing.
A master oceanographer and old friend returns!
Sunday, 6 December 2015 saw the return to Davis station of a sub-adult male elephant, tagged W6094. He had been first caught on 20 February 2012 at Davis when the Australian Animal Tracking and Monitoring System (AATAMS) seal team attached one of our state-of-the-art conductivity temperature depth (CTD) tags to him. At this time, he weighed 397 kg, was 1.92 metres long and had a maximum girth measurement of 1.90 metres.
He, and we’ll call him 'Agent W6094' given his extraordinary intelligence gathering feats, was next seen at Iles Kerguelen by our French collaborators on 4 January 2013 where he had hauled out to moult. At this time, the CTD tag was able to be recovered. In the period since the seal was first tagged, the data were transmitted via the ARGOS satellite and showed he had returned from Davis to Iles Kerguelen (2300 kilometres) and then left again on another 3500 kilometre round trip past Heard Island to the south east. The recovery of the CTD tag 11 months after deployment allowed the team to recover high-resolution conductivity, temperature and depth data (collected every four seconds).
While the seal has not been re-captured, he is currently in good condition with an estimated mass of 1300 kg. His presence on station has delighted the expeditioners, even if he has caused the occasional hiccup blocking roads and access to the helicopter-landing pad.
Despite being enormous, the male seal is surprisingly well camouflaged and some of the human station residents have mistaken him for a rock and got the shock of their lives when he moved and/or snorted.
With the image below, you can follow agent W6094 track in the Southern Ocean from Davis station in Antarctica back to his home on Iles Kerguelen in the subantarctic.
On Monday morning we did some training and set ourselves up to head off station and learn the essential survival and travel skills required for the long year ahead. We loaded up the quads and got out onto the sea ice with plenty of time to get to our destination, and learn some skills along the way.
Soon after we departed station we came across some beautiful scenery. The melting of icebergs brings a shade of blue that pictures cannot do any justice to, and a seal just happened to be in the right place for a photo. Nearly every time we stop on or near the sea ice we have visits from curious penguins, or we just seem to park on their path, and we have to take the opportunity for a photo - not that they are shy for a photo - and then they're on their merry way again.
We learned how to drill and measure the sea ice to ensure that we can operate vehicles on it safely, then made our way to our first destination: Bandits hut. We stayed the night and had a nice meal, and a good sleep, ready for what lies ahead.
On Tuesday we set off and headed up to the edge of the plateau navigating a lot of soft snow where we learned about quad bivvies (an emergency shelter) and how to set them up if needed. We then learned some quad recovery skills to get ourselves or others out of precarious situations (preferably don’t get into them in the first place).
We then made our way past Long Fjord to Platcha hut where we would spend the night sleeping out in a bivvy bag, another emergency shelter we carry with us all the time off station in case the weather turns bad quickly. The doc loved the idea of camping in Antarctica – can’t say I mind it either.
On Wednesday we learned some more skills of sea ice recovery if someone were to fall in, and navigation skills. We then made our way to Brookes hut for a bite to eat before heading back to station with a few more lessons on the way. Oh the joy of a nice hot shower when we returned.
Fast-ice research in Davis Harbour
Early this season Davis saw an influx of 12 sea ice researchers/engineers here to study various aspects of the near-shore fast ice, as supported by four complementary science projects. Land-fast sea ice is a pre-eminent feature of the near-shore zone, - it is a sensitive indicator and modulator of Antarctic climate processes, and is a structuring component of Antarctic marine ecosystems. Our projects is focussed on characterizing the fast-ice, snow and ocean characteristics before and during the spring transition and to link these to changes in the fast-ice associated algal biomass.
After a delayed arrival the team was quickly deployed thanks to favourable weather, speedy access to science cargo and early sea-ice training. First data of the snow cover was collected on the day of arrival at the Davis fast-ice edge and the full deployment of the various projects followed on the fourth day after the RV Aurora Australis arrived in the harbour. Since then, we had various sampling rounds, which vary from programme to programme, for example three day cycles for the sea ice trace-metal biogeochemical team, four day cycles for the fast-ice physics and ecosystems folks, and include about two full days on the fast ice to be followed by laboratory analysis of the samples. Weather and some broken gear have slowed some work but, with the support of an incredibly skilled and enthusiastic station support team, most of our work has moved on well.
Overall the fast-ice physics and ecosystems team (five scientists, a.k.a. boffins, support by one engineer) has worked on four transects. At each of these a remotely operated vehicle (ROV; equipped with a radiometer, cameras and upward looking sonar to detect ice draft) flew in the ocean underneath the fast ice along a 128 m transect as well as covering a 32 m by 32 m box, coincident snow-thickness and ice-surface temperature measurements were taken along the transect before a second radiometer was deployed directly underneath the ice through a core hole. In addition up to 12 ice samples were taken along the transect to determine the algal biomass within the fast ice. Detailed examination of the snow cover were obtained in dedicated snow pits at 0 m, 128 m and 512 m along the transect. At the same locations three ice cores were retrieved to derive vertical profiles of ice temperatures, salinity, density, structure and isotope composition. Detailed analysis of snow, ice and water samples were then undertaken back in the science laboratory or sea-ice freezer laboratory (at -22 Celsius). Some samples will be send to Australia for further analysis. Intensive snow-thickness measurements over the wider area, which are referenced to the ice surface by internal GPS, complement the survey.
As part of an over-winter project (ably handled by the wintering science engineer and supported by the wintering team) a pair of sea-ice mass-balance stations have been recording vertical profiles of ice and snow temperatures (at two centimetre intervals) as well as the near-surface ocean and atmosphere. To key these observations in with seasonal changes in the oceanic mixed layer, vertical profiles of the ocean properties were collected at the transect site as well as next to the over-winter ice mass-balance site.
Remembering that the activities described above form only a component of the overall sea-ice research carried out off Davis station during austral spring 2015 and that there are a number of other research projects going on this spring and summer, it is easy to imagine how busy the station has been supporting us in addition to their regular maintenance and infrastructure workload. Thanks for having us at Davis.
A busy social weekend
We had a very busy social weekend at Davis this week. On Friday afternoon the scientists on station hosted snacks and pre-dinner drinks for the entire station. Considerable effort went into staging the function with costumes, white lab coats and the mandatory beverage syringe. We even had some (unimportant) core ice to put into our drinks.
The Saturday was pub night, where the hard working chefs were given the night off and a number of expeditioners took over the cooking duties creating a pub menu: steak or parmas with chips and salads, and what better than pavlova for sweets? Then after dinner we were blessed with the appearance of the newly formed Davis band, aptly named 'N.T.R' which stands for 'Never to Return'. Well, their name definitely didn't do them justice as the adoring group screamed for four separate encores. There was hardly an expeditioner in the house who didn't get up and dance to the music. The band had a repertoire of over 14 songs which is amazing considering they had only been practising for less than a few weeks. The two lead singers, Mick and Sue, were outstanding and the guys on the instruments could all really play.
Prior to the band taking to the stage, there was an open mic session and quite a few budding singers and musicians took to the stage.
What a night!