In mid March 2015 the field component of the antFOCE ocean acidification project was concluded. This complex experiment was conducted as a collaboration of many scientists and engineers from around the world, and was coordinated by the Australian Antarctic Division. There is now a considerable amount of data and samples to process, and papers are expected to start coming out this year and later. The Aquation Submersible Respirometer System (known by the antFOCE team as “minichambers” to distinguish them from the larger acidified water incubation chambers) has provided some of the first data indicating a possible effect of acidified seawater on Antarctic marine organisms. Benthic diatoms live on or near the sediment surface and tend to migrate towards or away from the light depending on the time of day, and these unicellular algae appear to have been influenced by the acidified water in ways that differed significantly from the reference diatoms.
was deployed at 14 m under the sea-ice at O’Brien Bay, East Antarctica (near Casey Station, Windmill Islands). The substrate at this location comprises many small rocks and boulders interspersed with irregular shallow patches of soft sediment, typically one to three meters across. previous studies have identified diatoms as the dominant taxa on the sediment, and they can be seen as a red-brown surface layer. The Respirometer chambers were placed on the sediment which was approximately 5 cm thick. The Shutter Fluorometer was positioned over the diatom mat and carefully lowered down, with care taken to minimise disturbance and avoid the Shutter Sensor sinking into the mud.
PAR sensors were also deployed at two different depths, and stir and flush pumps installed to continually stir the seawater in the chambers as well as flush out the stale water every six hours. We aim to measure the rates of oxygen uptake, and possibly oxygen production, and from this data and core samples determine the rates of productivity of this benthic assemblage.
Movie (~30 sec): Aquation Respirometer Deployment 13Dec2014