Marine scientists study dynamic oceanography off WA coast

Murdoch marine scientists, Associate Professor Lynnath Beckley and PhD student David Holliday, are part of an international team studying the complex oceanography off the coast of Western Australia.

The team of 14 investigators and technicians from UWA, Murdoch University, the CSIRO, France, Spain and the USA left Fremantle on May 2nd to spend a month at sea on Australia’s national research vessel, the Southern Surveyor.

Whilst at sea they will track meanders in the Leeuwin Current to estimate their impact on Western Australia’s marine ecology. In autumn, as the Leeuwin Current intensifies off the shores of Western Australia, large meanders ~200 km in diameter develop and interact with coastal waters entraining planktonic organisms and advecting them offshore.

Shore-based oceanographers from the CSIRO will be in communication with the ship during the cruise to provide analyses of up-dated satellite images of sea surface temperature, chlorophyll concentrations and variations in sea surface height in order to guide the researchers to specific oceanographic features. (see the CSIRO marine web-site for latest image.)

Direct measurements of how these features influence biota will be made using a range of equipment that includes nets of various sizes and sophisticated underwater profilers.

The PhD study by Dave Holliday will specifically address cross-shelf transport of larval fishes induced by seasonal variability in the Leeuwin Current.

A previous study trip on the Southern Surveyor by Associate Professor Lynnath Beckley was reported in the School's 2003 Annual Report, (pdf file 800kb) alternatively view the entire 2003 Annual Report.

1 JUN 2006 - UPDATE: Scientists find kilometre-deep vortex

A huge vortex spinning off Rottnest Island has the strength to drag fish larvae offshore, according to a team of researchers including Murdoch University’s Associate Professor Lynnath Beckley. The scientists last week returned from a month-long research trip on the Southern Surveyor. The voyage was designed to probe the unusual eddy formed by the Leeuwin Current’s dynamic autumn acceleration.
The team also included scientists from The University of Western Australia, CSIRO and three American, French and Spanish research institutions.
Associate Professor Beckley, a fisheries ecologist, spearheaded the sampling for larval fishes.
UWA School of Environmental Systems Engineering biological oceanographer, Dr Anya Waite, led the 10-member multidisciplinary team found a huge vortex about 200km across and one kilometre deep, spinning at speeds up to 5kmh, just off the Rottnest Canyon. The vortex was carrying a heavy load of coastal plankton.
CSIRO’s Dr Peter Thompson investigated the impact, on the light-controlled primary production rates, of the deep mixing found within the rotating water mass, or eddy.
The team also used high-resolution underwater video to document the plankton concentrated within the vortex. Preliminary findings show that many coastal species, including larvae of important commercial species such as the rock lobster, were dragged offshore during the formation of the eddy.
The international mix of the research team highlights the global interest in work off the WA coast. Australia’s marine ecosystems are as unique and diverse as our terrestrial ecosystems but far less studied by Australian scientists.

Media contact: Adrian Kwintowski 9360 1289; 0406 497 206 (a.kwintowski@murdoch.edu.au)