CSIRO RV Investigator gathers data on the East Australian Current
Professor Iain Suthers, from the University of UNSW, and SIMS joined a three week voyage in June this year, as the CSIRO research vessel, the RV Investigator trawled the length of Australia’s eastern coastline, gathering data on the East Australian Current (EAC).
Thank you to ABC News for the full article
Key points:
- The research vessel collected data from devices moored up to 5,000 metres deep in the ocean
- The warming East Australian Current could cause an increase in inland rain events
- The trip marked the first investigation into jellyfish populations off south-east Queensland
The EAC is a current of warm water which flows like a warm oceanic river down the east coast of Australia from the reefs of northern Queensland to the underwater kelp forests of Tasmania.
At some points, the current is 100 kilometres wide, 1.5 kilometres deep and can carry 40 million cubic metres of water each second — the equivalent of 300 billion pints of beer.
With 29 scientists from six institutions on board, crew recovered and redeployed six moorings along the current that had been in place for nearly a decade, gathering data on the EAC’s flow rate, temperature and salinity.
Monitoring moorings 5,000 metres deep
Chief scientist on board Dr Christopher Chapman said the moorings were a “towering string of instruments” that were anchored on one end to the sea floor and on the other, to floatation devices used to keep the mooring upright — ranging from 500 to 5,000 metres long.
“You can think of it like the oceanic equivalent of a weather station,” Dr Chapman said.
“The East Australian Current is one of the primary drivers of climate along the east coast.
“We are in a very privileged position because what happens on the south-east coast of Queensland really controls everything that happens all the way down to Tasmania.”
Dr Chapman said a change in the distribution of species along the east coast has already been seen, with tropical species of fish moving in to southern waters, devouring kelp and sea grass forests at a rapid rate.
He said there were also isolated areas off Sydney’s coast where coral can be seen growing next to kelp.
“These changes are happening really rapidly,” Dr Chapman said.
“My colleague said that he thought he would be a grandfather before he saw these changes, but they’re happening right in front of our eyes,” he said.
“In Queensland, things are warming up but no faster than the global average, but further south, things are warming at three to four times the speed that things are warming globally.”
Dr Chapman said due to the variations, more data is needed to paint a clearer picture of how the EAC is affecting the environment, not just in the ocean but also on the Australian mainland.
“A lot of the water that evaporates and eventually gets rained over the landmass actually comes from the EAC,” he said.
“The warmer the water is, the more readily that water will evaporate and end up as clouds and eventually rain, so we could be seeing some interesting shifts in the climate.
“We’re only just starting to piece together the puzzle — we’ve got the pieces but they don’t quite fit together yet, but that is why it is so important that we keep monitoring the EAC.”
In addition to data collection on the major current, scientists also studied how jellyfish and larval fish mature in offshore eddies, or slow-moving oceanic whirlpools.
Professor Iain Suthers from the University of New South Wales, and SIMS said they were able to examine how eddies create important habitat for small, early-life stages of larval fish.
“That disturbance, that stirring, brings up nutrients and can actually bring larval fish in contact with their prey,” he said.
“We always think of nursery grounds as being in sea grass beds and in mangroves, which they are, but we haven’t really taken on board that offshore are these nursery grounds for herring and mackerel and anchovy.”
Professor Suthers said the findings of their studies will be of benefit to the fisheries industries.
