Southern Ocean Network of Acoustics (SONA)

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. To address these challenges we need to improve our understanding of the natural causes and consequences of Southern Ocean change. Sustained observations, which can only be large enough and maintained through international collaboration, will enable us to measure the baseline and future trends in the distribution and function of the ecosystem. The Southern Ocean Network of Acoustics (SONA) represents a group of scientific institutes and industrial partners who have united to measure an under-sampled component of the ecosystem - the mid-trophic level - , to agree common standards and protocols for data collection and processing and with a view to provide that data on an open access basis.

The Southern Ocean comprises more than 10% of the world's oceans and plays a critical role in the Earth's climate system. Changes in the Southern Ocean have global ramifications. The Southern Ocean has warmed, freshened, become more acidic and ocean circulation patterns have changed. Climate models suggest that it will continue to warm and freshen with less sea ice and changes in ocean currents. Changes in marine ecosystems in the Southern Ocean have been linked to these changes. The structure and function of Southern Ocean ecosystems are dictated by the unique habitat that exists in the Southern Ocean defined by seasonal light, low temperatures, water chemistry, depth, currents and sea ice. Potential impacts of climate change on the structure and function of the marine ecosystem will depend upon the sensitivity of the organisms to change in the physical environment. Detecting that change will depend on our ability to monitor the environment.

Mid-trophic level organisms range in size from small plankton (<2 cm), which drift with currents, to larger nekton (>10cm), which have the ability to swim freely. They are a diverse group that include squid, salps, krill and fish and play a critical role in Southern Ocean ecosystems. They regulate primary production involved in biogeochemical cycles and are prey for top predators (e.g. penguins, seals and whales). In the Southern Ocean alone they have a biomass equal to the human population, and globally they represent the largest unharvested biomass on the planet. Despite their pivotal role they remain one of the least known components of the ecosystem.

Making scientific measurements in the Antarctic oceans is not a simple task and bio-acoustic methods (using sound to measure organisms in the water column) present a cost-effective, widely used (frequently found on research and fishing vessels), large scale method for collecting information on the mid-trophic level organisms. However, in order for data to be comparable between vessels, standards and protocols are required in addition to bounding measurements with validation procedures. SONA will set these standards.

SONA will use bio-acoustics to monitor mid-trophic organisms at large spatial scales annually along transits to Antarctic research bases and fisheries sites. It will unite multi-national calibrated acoustic data from both research and fisheries vessels into a common accessible database. This data will inform on ecosystem based fisheries management, marine planning and monitoring impacts of climate change. Ultimately the project will input data and knowledge to international bodies such as the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and international programmes such as Integrating Climate and Ecosystem Dynamics (ICED) through the SENTINEL programme and the Southern Ocean Observing System (SOOS) and provide a road map for a global acoustic database of the mid-trophic level.

SONA will engage with a wide range of users:
(i) Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR). CCAMLR is keen to promote initiatives that are capable of resolving the impacts of human resource exploitation and climate change on ecosystem function. They have a strong focus on the South Atlantic, due to being the key area of the Antarctic krill fishery and would welcome the integrated overview produced by SONA.

(ii) The Southern Ocean Observing System (SOOS) and Southern Ocean Sentinel (SOS) are international programmes representing the SCAR and (ICED) IMBER communities charged with designing multi-disciplinary ocean observing systems. Implementation of SONA and production of an open-access circumpolar data portal will influence these programmes.

(iii) The Government of South Georgia and the South Sandwich Islands (SGSSI), who manage the fisheries in the territorial waters of South Georgia are interested in the potential for monitoring the marine environment using fishing vessels and ships of opportunity. We will discuss the protocols used and whether the SONA databases can deliver fisheries advice to this British Antarctic Territory.

(iiii) The fishing industry are interested in ecosystem based fisheries management and how they can contribute to the assessment procedure. SONA will demonstrate the use of acoustic data collected during transits in ecosystem monitoring and management, demonstrating methods in which the Antarctic fisheries community can contribute.

Techniques for engagement will include
(a) presentations at user's institutions, conferences, panels and committee meetings including SOS working meetings, CCAMLR Sub-Group on Acoustic Surveys and Analysis Methods, and CCAMLR Working Group on Ecosystem Monitoring and Management.

(b) participation in SONA workshops (on Ecosystem status in the Southern Ocean) by members of the SOS, SOOS and ICED community.

(c) presentations and discussions at the SGSSI government science and stakeholder meetings and other international fishery stakeholder meetings (through project partners).

We will work with schools, children and the public through developing an outreach site to the SONA data portal. This would include dissemination material such as information on the researchers and the food-web of Antarctica including interactive maps of mid-trophic level (krill and fish) distribution. We will also take examples of SONA engagement with the fishing industry, maps and examples of food-web organisms into the local school room and BAS exhibitions.