Two acoustic moorings have been deployed through the sea ice this winter at Davis research station. This scientific equipment will record baseline underwater soundscapes and will provide information on the presence of marine mammals (and potentially fish and crustaceans) throughout the year. Data provided by the project will contribute to environmental assessment activities being undertaken to inform the Comprehensive Environmental Evaluation (CEE) for the Davis Aerodrome Project.
The moorings are comprised of a string of components including weights, acoustic release, hydrophone assembly, external battery pack and floats. Once lowered through the sea ice, the floats allow the mooring to gently descend to the seafloor to depths of between 50 and 250 metres. The weights then anchor the mooring in place, and the string of floats suspend the hydrophone up off the bottom. The hydrophone will record underwater sounds throughout the year, and once the equipment is retrieved, data can be analysed to determine the underwater sound landscape.
The deployments during winter presented a few challenges, but nothing a team of highly skilled expeditioners could not handle. Step one, cut a hole through the sea ice using a chainsaw and ice augers, and then use all that SAR training to set up some ice anchors to lower 250 kg worth of mooring gently through the hole. Add a Hägglund winch for backup, and a sturdy tripod in case we need to pull it back out. Next gather all the hot water bottles on station, and set up some cosy sled beds to keep the temperature sensitive instruments warm (-5 degrees) on a -20 degree day, while connecting up all the components. Last, but not least, turn the equipment on before lowering it through the hole in the ice to the required depths.
By the second go at this we were pretty slick. Both instruments are now successfully deployed and happily recording new and interesting data under the sea ice. Tick!!!