APERO 2023
| Type | Oceanographic cruise |
|---|---|
| Ship | Thalassa, Pourquoi pas ? |
| Ship owner | Ifremer |
| Dates | 03/06/2023 - 15/07/2023 |
| Chief scientist(s) | MEMERY Laurent , TAMBURINI Christian , GUIDI Lionel  |
LABORATOIRE DES SCIENCES DE L'ENVIRONNEMENT MARIN - UMR 6539 Technopôle Brest-Iroise Rue Dumont d'Urville 29280 Plouzané +33(0)2 98 49 86 40 |
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| DOI | 10.17600/18000666 |
| Objective | APERO proposes to study the mechanistic functioning of the Biological Carbon Pump (BCP) (transport and storage of carbon in the deep ocean), with a specific emphasis on the mesopelagic ocean (200-2000m). Large uncertainties in the magnitude of the downwardcarbon flux as well as the roles of ecological, chemical and physical control processes remain. Currently, we are unable to accurately budget the amount of Organic Carbon (OC) reaching the mesopelagic zone relative to the mesopelagic heterotrophic carbon demand (the demand exceeds the supply in most studies). The overarching APERO scientific objective is thus to reconcile the discrepancy between the amount of photosynthetically produced particulate OC sinking out of the surface ocean and the biological carbon demand in the mesopelagic zone. Two main hypotheses have been tested during APERO: (H1) the export fluxes of Organic Carbon from the euphotic zone in the mesopelagic zone are controlled by the regime of surface production and pelagic plankton / microbial ecosystem; (H2) the carbon flux attenuation is driven by ecological and metabolic major processes in the mesopelagic layer. Thanks to a unique mechanistic and comprehensive approach, and using the most recent methodological developments in sensors and autonomous platforms, in `omics', and various modeling developments, APERO will lead to an improved understanding of:
The Porcupine Abyssal Plain Sustained Observatory, PAP-SO site (long time series station managed by NOCS), 16°W, 49°N is the target region: it is characterized by an intense spring bloom. The end of the bloom period (June/July) was chosen for the APERO cruise. This is because it is the time of the year when the particulate flux in the mesopelagic layer is the most intense, along with a strong variability of surface production states/regimes at small and medium scales. The choice of the PAP site is also motivated by leveraging our collaborative efforts with NASA EXPORTS (see `International collaborations') and with our NOCS colleagues (which requires to undertake the cruise in 2020). The study region will cover around 300 km x 300 km, in order to cover the submesocale features and to sample eddies, and the statistical origin area of particles reaching the sediment traps at PAP. The coupled approach considering 1D process studies as well as 3D high resolution coverage imposes the simultaneous use of two oceanographic vessels for 40 days. Because zooplankton and nekton stocks and migrations are crucial for APERO, the regional and local surveys have been performed on the N/O Thalassa, associated with a towed instrumentation (Moving Vessel Profiler - MVP200). The N/O Thalassa is equipped with state-of-the-art acoustics observing system to perform these investigations. A second larger ship, N/O Pourquoi Pas has been devoted to 4.5 days Process Studies Stations following drifting sediment traps. |