The Magazine for Underwater Professionals
Ocean glider tells quite a tale after 74 days at sea
A torpedo shaped underwater glider has just completed a 74-day journey through the waters of the Great Australian Bight returning loaded with information about the Bight – along with a few battle scars.
The ocean glider, operated by IMOS (Integrated Marine Observing System), an Australian collaborative research infrastructure supported by the Australian government and led by the University of Tasmania, made 344 dives, surfacing regularly to transmit data by satellite back to land where oceanographers have been analysing the data. The glider, which traversed over 1800 kilometres in the eastern Great Australian Bight, collected data on temperature, salinity and other variables from the ocean surface to a depth of 1000 metres.
On at least one dive the glider was attacked by a shark. Bite marks and a damaged oxygen sensor provide evidence the yellow metal object was mistaken for food and preyed upon.
The mission was part of the Great Australian Bight Research Program (GABRP), a collaboration between BP, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), the South Australian Research and Development Institute (SARDI), the University of Adelaide and Flinders University. This four-year, A$20 million (GB£11.9 million) research programme aims to provide a whole-of-system understanding of the environmental, economic and social values of the Great Australian Bight.
The Great Australian Bight is a unique marine environment and an area of high conservation significance. More than 85% of known species in the region are found nowhere else in the world. The highly productive region is home to great white sharks and iconic marine mammals such as whales, seals and dolphins.
The region produces 25% of Australia’s seafood production by value. It supports Australia’s largest commercial fishery by volume, the South Australian Sardine Fishery, as well as the valuable southern bluefin tuna, abalone and southern rock lobster fisheries. Aquaculture leases are spread along the coast and its coastal waters are significant for the region’s indigenous communities. Large marine parks have been established within the Great Australian Bight which is also a prime tourist destination.
The Great Australian Bight has been identified as prospective for oil and gas. In 2011, BP was granted four exploration permits in the Bight, and is now collaborating with some of Australia’s pre-eminent science institutions to enhance understanding of this vast expanse of ocean and its surrounds. The collaboration is delivering one of the largest whole-of-ecosystem studies ever undertaken in Australia.
Relatively little physical, chemical and biological data have been collected in the region, especially from the deepwater ecosystems of the central Bight. The research programme is seeking to build the first integrated model of how the biological and physical systems of the Great Australian Bight are linked and influenced by the environment around them. This will be vital information for all users of the Bight because it will provide a solid basis on which to measure possible human impacts and help industry and government plan for future activities.
“This was the third and final mission of the ocean gliders into the Great Australian Bight for the research programme to reveal the secrets from the deep regarding this dynamic and amazingly productive body of water,” says Dr Steve Lapidge, the programme’s research director.
“Judging by the tooth marks on the glider, it appears that one of the locals wants to protect its secrets,” he jokes.
The three glider missions into the Great Australian Bight have helped identify the major current systems, including an eastward flowing South Australian Current and the westward flowing Flinders Current, which can be distinguish based on depth integrated currents and temperature/salinity signature.
Dr David Griffin of IMOS OceanCurrent has been developing maps to track the glider’s mission. He has produced an animation which shows the journey of the glider and the measurements taken during its 74 days at sea.
A separate glider mission on the Bonney Coast has revealed very strong upwelling of cold water along the coast this austral summer.
Combined, the results of the geographically separated glider missions have provided valuable information about the origin of cold water which results in the high productivity of the Great Australian Bight that underpins South Australia’s important fishing industry.
Tim Moltmann, director of IMOS, is pleased to see that insights such as these have resulted from the deployment of its gliders.
“The Great Australian Bight Research Program is a great example of an industry-government collaboration using the IMOS national infrastructure to increase our knowledge of marine systems and ultimately benefit the Australian people,” says Moltmann.