Southern Ocean processes are intimately linked to some of the most pressing challenges faced by society today: climate change, ocean acidification and the sustainable management of marine resources. A good understanding of baseline levels of ocean processes and sustained circumpolar observations thereof are essential in order to observe and predict causes and consequences of changes in the Southern Ocean. Mid-trophic level organisms play a critical role in ocean processes and have a huge influence on top predators. Yet despite their abundance and wide distribution, information on their large-scale distribution has lagged behind.
The Southern Ocean Network of Acoustics (SONA) represents a number of scientific and industry partners that have united to implement a self-sustaining, long-term acoustic observing strategy of an under-sampled component of the ecosystem – the mid-trophic level.
Acoustic observations offer a cost-effective way to collect high resolution data on pelagic ecosystems over small and large spatial and temporal scales. Most scientific research vessels and many commercial fishing vessels now have echo sounders to collect this data. However, acoustic measurements cannot be used without standardisation of systems and appropriate validation. To that end a systematic and long-term strategy to establish an acoustic sampling programme including the implementation of standards is required. SONA aims to address this.
Partners are signed up through direct data sharing agreements or via parallel data portals such as Australia’s Integrated Marine Observing System (IMOS). Common standards and protocols for calibration and data processing will be aligned with existing international efforts by the International Council for the Exploration of the Sea (ICES), the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) communities, and IMOS with a view to providing data and documentation on an open access basis.
SONA Scientific Partners: Australian Antarctic Division (Australia) British Antarctic Survey (UK) Commonwealth Scientific and Industrial Research Organisation (Australia) Institut de recherche pour le développement (France) Institute of Marine Research (Norway) National Institute of Water and Atmospheric Research (New Zealand) National Oceanic and Atmospheric Administration (USA)
The IMOS processing suite for bio-acoustic data has provided a great framework to process acoustic data, and is now being applied to data from the South Atlantic (figure). It applies calibration data, noise filters and echo-integration of the raw acoustic data files to provide the user with quality-checked, geo-referenced calibrated water column backscatter (Ryan, 2011). Some fine-tuning of the method is underway in order to apply the process to non-transect data and other frequencies.
SONA is funded by the Natural Environment Research Council (NE/K011308/1). Additional funds come from the ANR Mycto-3D-Map (ANR-11-BSV7-0022) for Marion Dufresne II acoustic instrumentation and survey, carried out by the Institut de recherche pour le développement in association with the Institut polaire française.
ICES. 2014. A metadata convention for processed acoustic data from active acoustic systems, SISP 4 TG-AcMeta, ICES WGFAST Topic Group, TG-ACMeta. 40 pp. Ryan, T. E. (2011). "Overview of data collection, management and processing procedures of underway acoustic data - IMOS BASOOP sub-facility." Australian Ocean Data Network
SOOP Data Collection and Processing