Deepest ever photographs of marine biodiversity in Australian waters
The CSIRO Wealth from Oceans Flagship and the Deparrtment of Environment Water Heritage and the Arts have collaborated with scientists from the California Institute of Technology and Woods Hole Oceanographic Institute to deploy a deep-diving submersible on deep-sea coral reefs in the Southern Ocean. The un-manned submersible, the Autonomous Benthic Explorer (ABE), is a robot designed to photograph and survey marine features at depths to 3000 m, more than a kilometre deeper than has previously been studied in Australian waters. ABE was deployed on six missions during a three-week cruise on the Southern Surveyor, reaching depths of 2960 m in the Tasman Fracture Zone Commonwealth Marine Reserve and taking over 6000 photographs of the sea floor. The photographs are still being analysed in detail, but already indicate sites from which fossil and sub-fossil corals can be collected for paleo-oceanographic and climate reconstruction (a primary objective of the missions) and show a rich benthic community well beyond depths expected. Hard corals were found as deep as 2300 m, whereas soft-corals, in a variety of taxa, were found as deep as ABE could dive, living in complete darkness and at temperatures of 1-2ยบ. Over 1500 coral samples were obtained from shallower depths (1000-1500 m), using dredges, to start analysing the age and growth of the reefs and begin paleo-climate analysis. More samples, from greater depths, will be collected on a follow-up cruise in December 2008 using the US deep-sea vehicle, Jason. It is expected that Jason will sample to at least 4500 m, extending even further our information on biodiversity in the marine reserves.
