In the Operations Laboratory we monitor all data collected by the ship. Nine video cameras are mounted in key areas and we can switch from views of the waves ahead to checking the wire laying on the winch spools or check the angle of the wire we have our instruments dangling on over the stern to make sure it has not gone under the ship (see camera in photo yesterday). Until a couple of days ago there were only 21 screens and paper recorders displaying real-time data for us to monitor. Now there are 22! Cameron (Geoscience Australia) has squeezed a laptop between two monitors with his 3D visualization of the sea floor with our exact location and track overlaid. It is a very useful addition.

We continued our survey mapping the margins of the Fairway Basin using all our remote sensing techniques: multibeam bathymetry, seismic, magnetics and gravity. What we have found is that existing maps lack real data or are wrong. A ridge shown on the charts as 30 km long and 300 meters high does not exist. This is not surprising to us as marine scientists because the data in this area is before GPS. Our data will be sent to the GEBCO data base (General Bathymetric Chart of the Oceans) so the charts can be corrected base on our one swath track around this basin. This sea floor is claimed by Australia as part of its extended continental shelf under the UN Law of the Sea. In fact Australia claims over 12 million square kilometers of the sea floor, nearly double the size of its land area so there is a lot of work to be done with very limited resources available to universities and GA.

While the dredge was coming in we had a lecture from Graham Logan (Geoscience Australia) on methods used to locate natural seeps of oil and gas from the sea floor. He showed how Synthetic Aperture Radar (SAR) from satellites is commonly used to identify slicks on the sea surface but these slicks need much more investigation before they can be related to seeps on the sea floor below. He led a team to ‘ground truth’ these slicks off northwest Australia. They did exactly what we are doing here only in shallow water 50-100 meters deep. They found that bathymetry caused some slicks, tidal currents caused other and coral spawning also caused some. Only by doing multibeam mapping, seismic and bottom sampling could they confirm the real gas seeps.

Graham also explained how his samples from the cores would tell if methane was seeping up from below and if it was methane from bacteria or hydrocarbons. Our cores have penetrated below the brownish oxidized mud into the grey anoxic mud. Here the bacteria use sulphate in the groundwater as energy and burn organic carbon or methane if it is present. Because there is little organic carbon in these sediments then if he finds sulphate is being used up as he analyses down the core then the bacteria must be using methane from below. He will measure total carbon dioxide levels to confirm if bugs are turning methane into carbon dioxide. If I haven’t already lost you he will also analyse biomarkers which will tell him he type of bacteria present. Not to mention major element analysis and stable isotopes of carbon. Fascinating stuff. The students now have two more research papers on their take-home CD to digest.

All the methods we are training the students to use on this cruise have their scaled-down equivalents for practical use in ports and harbours and coastal waters.