Austral Seals Observatory: National Observing System: Mammals as Ocean Samplers and Long Term Ecology and Evolution Monitoring. Southern Ocean Seal Observatory

The Austral Seals Observatory (ASO) is implemented since 2004. The ASO has two components the SNO-MEMO and the SEE-Life Elephant Seal Observatory (SEE-Life-ESO) one. Both components are part of the Zone Atelier Terres Australes et Antarctiques (ZATA) animated by CNRS INEE. The SNO-MEMO is labelled by INSU (CSOA) and alongside SNO Pirata, ARGO and SSS, of the OHIS research infrastructure project (Océan Hauturier In Situ; S. Speich, P. Lherminier, L. Coquempot). The Southern Ocean, which plays a fundamental role in regulating our planet’s climate, absorbs 70% of the excess heat from the global ocean and traps 40% of the CO2. Furthermore, this ocean is home to an ecosystem that is likely to be highly vulnerable to global warming, as the distribution of many species of phytoplankton and zooplankton are highly constrained by thermal conditions and highly dependent on the Antarctic pack ice zone. As part of SNO-MEMO, seals, mainly elephant seals, living in polar and sub-polar environments and known to dive continuously and deeply are fitted with beacons designed to collect 1) hydrographic profiles from CTD sensors (temperatures, salinity); 2) biogeochemical profiles (chlorophyll-a, oxygen) and 3) biological profiles (bioluminescence, plankton and micronekton; encounters with prey). The in-situ data collected represents the bulk of the data available for this region of the world and enables the interrelationships between physical, biogeochemical and biological conditions to be studied. Working in close partnership with the Australian Integrated Marine Observing System and with the support of the IPEV and CNES (Pole ODATIS) the SNO-MEMO collects CTD profiles distributed throughout the year in the Indian sector of the Southern Ocean, representing the only continuous series of oceanographic conditions over all seasons. A judicious choice of species (elephant seals or Weddell seals), sex and age of the individuals has made it possible to obtain data from under-sampled regions such as the Antarctic pack ice zone, the Antarctic or Kerguelen shelf and the oceanic regions. Over 80% of the oceanographic profiles available south of 60°S and 98% of the data associated with the pack-ice zone are now sampled by austral seals.
The SEE-Life Elephant Seal components labelled by CNRS-INEE in 2024, covered the ecological part of ASO. It collects long-term ecological information on the at sea-behaviour: distribution, diving, foraging efficiency; demographic parameters (size structure of the breeding females, assessment of body condition and the weaning mass of new-born pups); Carbon and Nitrogen Stable Isotope information. In addition, we proceed to the monitoring of the biological component of the Southern Ocean by implementing new breakthrough biologgers. All those parameters are analysed in relation to the oceanographic Environment context. A significant benefit of ASO is that it can address questions relating to physical, biogeochemical and ecological oceanography and at the interface of these disciplinary fields as well as assessing the ecological consequences of the ongoing changes. The in-situ observations made are also widely used to validate satellite measurements. Coupled with satellite observations, they can also be used to assess the influence of the oceanographic landscape on the structuring of biological resource fields.