| Abstract | Oceanic Oxygen Minimum Zones (OMZs) are known to play a key-role on the evolution of climate (greenhouse gases production) and living resources from ecosystems to fisheries (nitrogen loss, respiratory barrier for zooplankton and fishes). In response to climate and environmental changes, OMZs would contract during cold periods and extend during warm periods. Despite the worrying problem of ocean deoxygenation due to global warming and human activities, OMZs have not been extensively studied. Current global models exhibit severe biases in simulating the vertical and horizontal O2 distribution in the OMZ, although oxygen is one of the first oceanographic parameter being measured.
The AMOP («Activities of research dedicated to the Minimum of Oxygen in the eastern Pacific») project will investigate the mechanisms leading to the OMZ existence off Peru and its variability from hourly to centennial timescales. The Central Hypothesis of this project is based upon a two-layers conceptual model of the OMZ: the oxycline and upper OMZ core where physics and biogeochemistry contribute comparably to the rate of O2 changes, and the lower OMZ core where physical processes dominate the changes in O2. Conversely to other studies dedicated to different OMZ impacts, AMOP is focusing on the oxygen parameter, with the objective to carry out a quantitative and comprehensive O2 budget considering physical (advection/diffusion) and biological (O2 consumption/production through bacteria, phytoplankton and zooplankton) contributions. The project implies a transdisciplinary approach: biogeochemistry, microbiology, physics, coupling with the atmosphere, acoustics, ecology, study of benthos, paleoceanography, all aiming towards the understanding of the O2 fluxes. The approach is based on: i) a 30-day cruise with two ships in simultaneous (L'Atalante from IFREMER and a Peruvian vessel from IMARPE), associated with glider and Argo float experiments, ii) a mooring (> 3-yr) on one of the historical IMARPE station coupling water column and sediments (the mooring is deployed since January 5th, 2013), iii) a modeling platform in order to bridge the gap between sampled and non-sampled spatio-temporal scales, and to assist the interpretation of our full data set (from in vitro to in situ, satellite and proxy data). The cruise with on board experimentations and use of innovative technologies (e.g. Pump-CTD, HPBs-O2, IODAs/sediment traps) is focused on 9 fixed stations (3days) and on 3 transects in the North (7°S), Center (12°S) and South (14°S), covering 3 distinct topographic conditions of the OMZ system: the continental shelf, the slope, and the open deep ocean.
AMOP involves 14 research units in France, 7 research units from 2 Institutes in Peru and 10 Institutions in 6 other countries (China, Denmark, Germany, Ireland, Mexico, USA) acting as an international consortium on the deoxygenation topic (~90 participants). It is associated with new programs, both in terms of themes and multidisciplinary approaches, Regional (RTRA/MAISOE, ICE), European (SENSEnet, HYPOX, EURO-ARGO, EUR-OCEANS) and International (SOLAS, IMBER, GEOTRACES). AMOP is viewed as one of the main pilot projects of an initiative to coordinate, on the OMZ and in partnership with Peruvian Institutions, international actions (e.g. German SFB754; US Torero) from 2013-
2014: cruises, scientific flights, experiments, long-term monitoring, and modeling. Presently, the AMOP project is approved and labeled by LEFE-CYBER and GMMC from INSU. The total budget requested to ANR for the 3-yr period amounts to 624,383 ' for the science part and to 62,438 ' as a participation for the R/V Atalante fees (estimated to 747,120 ' by IFREMER) thus a total of 686,821 '. |
