Drs Amandine Schaeffer and Michael Hemming recently returned from a month-long trip aboard CSIRO Research Vessel (RV) Investigator along Australia’s eastern coastline. Dr Schaeffer was part of the Principal Investigator team, working collaboratively with scientists from CSIRO, Griffith University, and UNSW BEES. 

Researchers gathered data on the changing East Australian Current [EAC] and observed its effect on fish reproduction. 

Dr Schaeffer and Dr Hemming and were both part of the Physical Oceanography team and helped with the deployment and recovery of deep moored oceanographic instruments (down to 5,000 metres), in waters off South East QLD. These instruments measure the variability of the EAC and its properties in temperature and salinity.

“CSIRO scientists are now analysing the 18 months of data we collected from the deep ocean moorings, which will be invaluable to understand the trends in the EAC, including below the surface where most of the transport occurs,” Dr Schaeffer said.

They also analysed real-time data to steer the ship towards interesting small-scale ocean eddies in the vicinity, allowing extensive new physical measurements and samplings from the UNSW marine biologists also on board the vessel. 

“We believe that these 20 to 50km patches of rotating water are critical for the interaction and transport of water from different origin (from the shore, the tropics or deep water), creating a very distinct habitat for marine life.”

Among many memorable experiences on board, one involved navigating in between fish trawlers fishing at the same spot that they were interested in sampling. An eddy was present here, characterised by strong non-linear processes which trigger the vertical flux of nutrients enhancing biological productivity. 

In another dicey encounter, they witnessed dolphins playing around their towed instruments, which triggered the altimeter alarm - designed to go off when the instrument is too close to the bottom.  

They also observed a stunning lunar eclipse at sea.

For more about the trip, please see the UNSW Newsroom article: Four week voyage yields secrets to changing oceans.

Images, from top: The Physical Oceanography team;
Amandine Schaeffer (right) and colleagues;
Mooring operations on the back deck of RV Investigator [image credit: Mike Watson];
Michael Hemming (middle) and colleagues [image credit: Maurice Huguenin-Virchaux].