The APERO campaign aims to study the the Biological Carbon Pump (BCP) (transport and storage of carbon in the deep ocean), with particular attention to the mesopelagic ocean (200-2000m) in the area of the Porcupine Abyssal Plain in the North Atlantic. Strong uncertainties in the intensity of the sinking carbon flux, as well as the ecological, chemical and physical processes controlling it, remain. At present, we are unable to precisely balance the quantity of Organic Carbon (CO) reaching the mesopelagic zone with the heterotrophic carbon demand of this mesopelagic zone (the demand exceeds contribution in most studies). The ultimate scientific objective of APERO is therefore to reconcile estimates of the quantity of CO particulate matter produced by photosynthesis leaving the ocean surface (export) with the biological carbon demand in the mesopelagic zone. Samples for diversity were collected using Niskin bottle, phytonets (35 µm), particle traps and deepnets (20 µm). The samples were fixed with acid Lugol and basic formalin for observation by optical microscopy (Nikon TE-200) and filtered on a polycarbonate filter then coated with gold for observation by scanning electron microscopy (Phenom ProX) coupled with EDS which allowed for the determination of Si-, CaCO3- or Strontium-based organisms.