The Antarctic marine environment is patchy at spatial and temporal scales. That is, there are large assemblages of biomass, collected in swarms of species such as Antarctic krill, that may be kilometres long, occur seasonally, and may be separated by tens of kilometres. Furthermore there is a relationship between sea ice extent and krill swarms with time-lagged covariance of approximately seven years. Antarctic krill is widely considered a cornerstone of the Antarctic
ecosystem as it bridges the primary producing under-ice algae and open water phytoplankton with fish, seals, whales and sea birds, as well being the focus of a multi-billion dollar fishery. Understanding the drivers of patchiness in krill and other species, and the impact of a warming Antarctic continent on the Antarctic marine environment, is central to effective conservation and efficient fisheries management efforts in the Southern Ocean.
Unravelling the complex biophysical and trophic interactions driving inter-annual stocks of biomass means making measuremenst at fine scales, in relatively short, targeted process
studies, and at larger, basin scales with observation sustained over years. The necessary
observations are beyond what is feasible using research vessels, particularly as days at sea available to science are shrinking globally. The development of suitable autonomous platforms, with appropriate instrumentation and our understanding of their effective use is therefore particularly urgent. Instrument suitability is determined by the payload capacity of the various
platforms, which are in most cases smaller than those of research vessels. In addition, autonomous platforms currently have limited capacity for the collection and analysis of physical samples; a particular issue for the identification of acoustic targets and the subsequent application of target strength models for biomass calculation. Traditional methods of survey are therefore not likely to be fully supplanted by autonomous platforms but rather heavily augmented by autonomous platforms as part of observing systems. To be effective and scalable, these systems will require varying degrees of onboard processing of data, adaptive mission planning and robust multi-node mission management; fields which are often considered in isolation of environmental science.
The roles that AUVs and other autonomous platforms play in filling the gaps in our knowledge and the state of existing acoustic sensing technology will be described. The developments in vehicle and sensing technology, and the understanding of data products needed to achieve multi-scale marine ecosystem observation and the challenges of building big, interdisciplinary observing systems will be discussed.