Underwater "house" advances reef studies
Nine days in a state-of-the-art underwater "house" which enables scientists to live and work in the ocean for weeks at a time has advanced a University of Queensland's researcher's Great Barrier Reef studies.
In August, Vision, Touch and Hearing Research Centre QEII research fellow Dr Justin Marshall joined three international scientists in the permanent structure known as the Aquarius anchored 20 metres under the sea in the Florida Keys National Marine Sanctuary. PhD student Ulrike Siebeck was part of the surface-based science team supporting the aquanauts.
"The advantage of the locomotive-sized Aquarius is that you live at 2.5 atmospheres instead of the normal one atmospheres pressure enabling dive trips of six hours duration each day rather than the one hour maximum you achieve if you are based on a boat," Dr Marshall, an Australian Research Council QEII postdoctoral research fellow, said.
"It is a saturation habitat meaning aquanauts breathe air at the same high pressure as the water outside and their body tissues are ?saturated' with nitrogen at more than twice the normal amount. While it takes 17 hours to decompress Aquarius aquanauts, saturated divers can stay underwater indefinitely, truly ?living under the sea'. "Access to the Aquarius - the only research habitat in the world where people can live and work underwater for weeks at a time - has greatly advanced my understanding of the reef environment. This information will assist my work examining the fish of Queensland's Great Barrier Reef."
Living underwater had its drawbacks, Dr Marshall said. "After nine days, we all felt a bit like sardines milling around a large can. The high level of nitrogen in the blood made us feel very tired and sometimes we experienced a similar sensation to being slightly drunk," he said. The Aquarius habitat, often referred to as the "NASA of the sea", is part of the United States National Undersea Research Program (NURP). Led by Professor Tom Cronin of the University of Maryland and Dr Nadav Shashar of the Marine Biological Laboratory at Woods Hole, the recent mission examined light and its effects on coral, the more extreme example of this being coral bleaching.
"They measured polarised light underwater, a facet of light humans can't see but many marine creatures such as the mantis shrimp can. These animals may use the light for navigation and ?secret-signalling' to each other," Dr Marshall said. This ?language of the reef' involving light and colour is the subject of Dr Marshall's Australian research. He aims to discover the purpose of colour in the lives of marine creatures such as the crustaceans and fish of the Great Barrier Reef. Dr Marshall's previous work in the United Kingdom centred on stomatopods, commonly known as mantis shrimps, and produced the first proof of colour vision in any marine invertebrate. Very little is known about marine creatures' visual abilities, according to Dr Marshall. He said a likely explanation for colour communication in the marine world was either to attract mates or ward off rivals.
For more information, contact Dr Justin Marshall on telephone (07) 3365 4484.
