The Western Australia Moorings sub-facility is responsible for a collection of moorings designed to monitor the along-shore and cross-shore variability in the Leeuwin Current and continental shelf currents off the southwest coast of Australia. The sub-facility also maintains the Rottnest National Reference Station moorings and carries out monthly water sampling at the station. Moorings in the region also monitor processes within the Perth Canyon. The time-series monitoring of physical and biological parameters provided by these moorings supplements past and current research activities in the region based at the CSIRO, the Department of Fisheries WA, Western Australia Marine Science Institution, and Western Australian Universities.
The sub-facility currently maintains four shelf moorings, including three Two Rocks moorings and one Perth Canyon mooring, located off Perth, Western Australia. The Two Rocks line contains three mooring which transect the continental shelf north of Perth at the 100m, 200m, and 500m isobath. Primarily these moorings are instrumented with acoustic doppler current profilers (ADCPs) and thermistor strings allowing the structure of the Leeuwin Current on the shelf to be determined. And ADCP mooring at about 40 m serves as a test site, which also provides a valuable coastal current data. Around the Perth Canyon, one slope mooring, located in 200 m water at the head of the canyon, monitors processes in and around the canyon. Two of the moorings also sample biogeochemical parameters. The moorings are located within coastal radar coverage off Perth, and are on the glider deployment tracks. The cross validation of the different data streams provides valuable understanding of coastal processes off Perth such as the interaction between the Leeuwin Current and the wind-driven Capes Current and mesoscale and sub-mesoscale eddy activities. Acoustic noise loggers have also been deployed in the Perth Canyon to provide baseline data on ambient oceanic noise, detection of fish and mammal vocalizations linked to ocean productivity and whale migration patterns and detection of underwater events.
The Western Australia mooring sub facility started the IMOS operations in 2008. The sub facility was responsible for maintaining five shelf moorings at Two Rocks and three moorings in Perth Canyon. The shelf moorings were consolidated to the four current sites in 2014. The sub facility was also responsible for maintaining the National Reference Station moorings at Rottnest and Esperance, as well as carrying out water sampling at three National Reference Stations including the Ningaloo Station. The Rottnest National Reference Station was initially established by CSIRO in the 1950s.
The shelf moorings were initially equipped with temperature and pressure loggers, some with ADCPs. With the additional support from the CSIRO capital expenditures, currently all the moorings are equipped with ADCP and salinity sensors, and two of the moorings carry biogeochemical sensors. All the moorings are maintained about every six months.
The National Reference Stations have an ADCP mooring and a biogeochemical mooring. The moorings are serviced every three months. The water sampling is carried out monthly at the Rottnest station, and quarterly at the Esperance and Ningaloo stations. The Esperance and Ningaloo stations are no longer continued after the 2014 moorings network consolidation. The water samples from the National Reference Stations are analysed at the CSIRO Floreat, Hobart, and Cleveland labs.