The AUSCAN voyage set off from Hobart on 19 February 2003, on a 16 day voyage to unravel the secrets of the seabed in Australia's southern waters. Research scientists from five countries were aboard, hoping to obtain vital information for their specialist fields. Public Affairs Officer Katrina Haig was also aboard, and kept a daily diary of life on the voyage. Read her story below.
The day has been spent stowing my possessions on board and preparing for a 6pm departure.
My cabin is very comfortable and I’m really excited about meeting the range of scientists from around the world who are part of this voyage. I’m looking forward to tomorrow when the real adventure begins!
The Marion Dufresne set sail from Hobart last evening and to the relief of many first-time voyagers on board, experienced a smooth sailing out of the Derwent Estuary. At 7pm, we met in the dining room where we were served a sumptuous four course meal, and many of us took the opportunity to get to know a little about our fellow passengers. As far as research vessels go, the Marion Dufresne is luxuriously equipped. Our cabins are spacious and come complete with double beds and ensuites. The silver service in the dining room adds an unexpected touch.
After such a salubrious start to the voyage, the conditions at sea gradually worsened as we rounded the southern tip of Tasmania. For seasoned sailors this didn’t cause much consternation, but for those of us unused to the roll and pitch of a ship at sea, it gave us the opportunity to find our sea legs pretty quickly. (Coming from a family of seasoned sailors, it seems my sea legs are as sturdy as ever).
This morning’s conditions found the ship sailing on a big swell from the south of about three metres. Fortunately most of the travellers are faring well, with only a couple suffering from the dreaded mal de mer.
The research crew that has joined the vessel from ANU, GA, SARDI and other research institutions hail from all corners of the globe. Aside from the French and Australians, we have German, Russian and American participants, including a sizeable number of undergraduate and PhD students who are all excited at the prospect of getting some hands-on experience in their particular area of research.
This first day of the voyage has been a day of orientation. A morning meeting gave us the chance to learn more about who is on board and what role they will play in the AUSCAN voyage. We have just returned from the ship’s safety drill, where we all had the chance to don a survival suit in the unlikely event of an emergency.
Geoscience Australia has a team of three on board the ship: Marine geophysicist Peter Hill, fellow marine geophysicist and swath mapping expert James Daniell, and marine geologist Alix King.
Peter and James have been busy collecting some swath data across the upper continental slope off Tasmania’s west coast. The have also been gathering data from the sub-bottom profiler across a massive sediment slope off south-west Tasmania near Port Davey.
“We’ve now changed back to the multi-beam sonar and we’ll run multi-beam mapping from now until we get to the Murray Canyons region,” said Peter. This technique is a seafloor mapping system that gives very good bathymetry and backscatter data.
In the meantime, the French scientific unit aboard the ship is preparing a core sample that was collected on a previous survey south of Tasmania. Australian National University group leader and marine geologist Patrick de Dekker is looking forward to the opportunity studying this core sample will provide for his team of researchers. It will assist with some core study experience ahead of the core samples that are yet to be collected off the west coast of Tasmania and the Murray Canyons region.
After the first 24 hours on the ship, the new sailors are starting to get accustomed to life at sea. Many who had reported a poor first night’s sleep managed to fare better, and the sea conditions were easier than the previous evening.
Last night, Patrick De Deckker gave a short presentation on the French explorer Nicolas Baudin, who explored the Murray canyons region two hundred years earlier. The presentation was followed by a welcome drink courtesy of the French, which was warmly welcomed by the passengers.
This morning started with an early petit dejeuners, and there was a sense of anticipation among many of the scientists as today they will start to sample the sedimentary core collected from the South Tasman Rise in the previous survey. As many of the research crew are students, this will be their first taste of core sample analysis.
A quick trip to the bridge shows today’s expected conditions to be mild, with moderate to rough seas. The temperature at 10am was 19.4 degrees C, with 22 knot winds, 79% humidity and a swell of 3 to 4 metres. Our speed is 14 knots, and our position at this time is 38.57° S and 142.3°E.
Today and tomorrow will provide the best opportunity for our whale watcher, Marg O’Toole, who works with the Deakin University whale research team, to identify any giants of the deep that might be nearby. As we approach the Murray Canyons region, we are moving in closer to the Continental Shelf off the south west of Victoria, where it is known that blue whales feed at this time of the year.
With lots of white horses and a large swell, the sea conditions are not ideal for the task.
“When we look to identify whales, we first look for the blow, which can differ between species,” Marg said.
“They can be very difficult to identify, which is why we look for their back and dorsal fin as they dive to help us with identification. Whale watching can be very intensive, as you need to watch the surrounding ocean very closely for hours at a time.”
Marg has observed many sea birds, from the huge and graceful albatross, to the shearwaters who skim across the sea’s surface.
Peter Hill, from Geoscience Australia is heading up the geophysics and swath mapping team. Overnight, the team was able to map the heads of the canyons of the north west of Tasmania, King Island and south west Victoria. This has resulted in excellent data that will be used to fill some of the gaps in previous knowledge of the area.
“All of the data we are collecting will give us better understanding of the structure and sedimentology of these spectacular formations,” Peter said. “So far, the data we’ve managed to gather is really exciting, especially as this is the very first time that we’ve managed to map the heads of these canyons. Now, we can see for the first time where the canyons initiated, just below the shelf edge.”
Patrick De Deckker reported that testing of the Tasman Rise core sample had provided a lot of activity for the ANU team.
To test the core samples, first the cores are split along their length and observations and testing undertaken.
Sedimentologist John Magee from ANU explained: “It’s a three stage process. First, the core samples are digitally photographed. Then the samples are logged, which means a description is made of the sediments, structure and colour by a sedimentologist. Then a spectrophotometer is used to detect the graduation of colour changes within the core sample. A gamma logger is also used to track the density and porosity of the sediment.”
The team is particularly excited as very early tomorrow morning we expect to reach an area where the first long core will be taken from the eastern flank of one of the Murrray Canyons. This will be the first time ever any sedimentology has been conducted in this area.
“No-one knows what lives on the seafloor. With their unique geological formations, the Murray Canyons are likely to yield some very exciting results. We fully expect to make some very important and exciting discoveries,” John said.
An early start to the day today with the AUSCAN science team attempting the world’s first deep sampling of sediment in the Murray Canyons region. The lab is a hive of activity at 04.00hrs, with the sedimentologists and swath mappers working together to determine the optimal site to send down the corer.
Peter Hill, from Geoscience Australia, heads up the swath mapping team which has been gathering data to provide detail about the topography of the seafloor and its mantle of sediment. Patrick De Deckker, from ANU, consults with Peter to determine the best possible location. The sea conditions are close to perfect, with a calm, flat sea and a light rain which helps keep the water smooth. A decision is made, and then things start to happen very quickly.
The scientists look on with anticipation as the French crew lower a six tonne, 60 metre long “CALYPSO” corer into the waters on the eastern flank of the Murray Canyons region. The CALYPSO corer was developed by Yvon Balut, of the French Polar Institute, who oversees the operation. It takes about thirty minutes for the corer to reach the sea floor, the core triggers and quickly penetrates nearly thirty three metres beneath the seafloor at almost 900 metres depth. At 06.30hrs the painstaking process of winching the core back to deck takes place under the watchful eyes of the science crew. No-one is sure what secrets the core will reveal.
There is elation as the core is measured at close to 33 metres in length, and Australian National University’s Patrick De Deckker, says he is delighted with the successful result of the operation.
“This is the first time deep sedimentary core sampling has ever taken place in this region. We are absolutely thrilled that we were able to retrieve such a long core, and we are hoping it will provide us with the key to unlock some of the archives of the past,” Professor De Deckker said.
The Marion Dufresne uses the latest sonar technology, known as “swath mapping”, to get detailed information about the topography of the sea floor. The ship is also equipped with a sub-bottom profiler which gives an indication of the thickness of the sediment.
Peter Hill explains: “We’ve managed to get some excellent swath mapping data so far through the AUSCAN voyage. We were able to work together with Patrick to advise on the optimum location to send down the corer. This result is very pleasing for us all.”
“From the sub bottom profiler we were able to determine there were more than 40 metres of soft sediment in this area, and to retrieve a core of this length is a phenomenal result,” said Peter.
Patrick says that initial results have shown the core displays a large degree of sedimentary layering, indicated by a variation in colour visible to the naked eye.
“One significant outcome is that the upper two metres of the core are pale coloured and we estimate this represents the last 10,000 years when southern Australia, at times, was much wetter than today,” Patrick said. “Below two metres, a very dark and thick layer possibly represents events when Australia was much drier and colder; this coincides with the existence of large ice sheets that covered most of Canada, a large portion of the United States and northern Europe.”
The French and Australian science teams work together like a well oiled machine to measure, label, segment and process the core sample.
Meanwhile, on the bridge, whale watcher Marg O’Toole had her first sightings of cetaceans for the voyage.
Shortly after 09.00hrs, five minutes after spotting an Australian fur seal on the starboard side of the vessel, Marg observed a pod of 60 common dolphins playing in the bow wave on the port side of the ship.
“It was pretty exciting,” said Marg. “The ship was located about 35 nautical miles south of Kangaroo Island at the time, and this is AUSCAN’s first sighting of whales, as dolphin are actually a type of whale.”
A couple of hours later, Marg spotted a sea lion, and observed lots of sea birds including black browed albatross and fairy terns.
At 16.30 hours, Patrick and Peter and crews consulted once again to determine a new location to take a multicore sample later this afternoon. This type of sampling gathers sediment just under the seafloor, and collects the water immediately above the collection site. The CALYPSO core sampler’s immense weight means it penetrates well below the surface of the seafloor, and often disturbs seafloor surface sediments. The multicore sample will provide this additional data.
Meanwhile, Lachie McLeay from SARDI is eager for the multicoring to get underway, as this will provide him with an opportunity to carry out a “plankton tow”, where a specially designed net is dragged out of the stern of the ship to collect samples from the sea’s surface.
“I’m pretty excited about getting to do the tow. No-one has ever tested what’s living in this part of the world, so who knows what we might find?”
Tomorrow will tell.
The Marion Dufresne
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