This cruise, in line with the work initiated during MALIS 1&2, is therefore de facto called MALIS 3 for "Management of Atolls using ALIS 3".

Two sites are priorities for this campaign: Apataki and Takaroa. Apataki is a new site for science, priorities in terms of aquaculture and pearl farming. T Takaroa is a site already studied by several projects, particularly in 2008-2012 (FED project), but a particularly long bloom caused high mortality of benthic populations in 2014 (Rodier et al. 2019) and the recovery of the lagoon is studied and modeled since 2019.

The objectives of the MALIS 3 campaign are therefore to:

• Collect physical data from Apataki Lagoon. Measurements include fixed stations (ADCP and T/P sensors).
• Hydrobiological measurements on intra-lagoon networks (chla, nutrient salts, production, and cast CTD). Carry out high frequency CTD cycles in order to observe the daily variability of the water column in front of the pass (Temperature, Salinity, Irradiance, Fluorescence, Turbidity). This type of data was acquired over 2 cycles of 36 hours during MALIS 2 on Raroia (bathysonde every 30 min), and provides important information on the jet entering the atoll (under evaluation).
• Inventory and map the stock of wild oysters by scuba diving (Apataki, Takaroa).
• Map the outer ocean slope and the passes of several atolls of interest (Apataki, Takaroa, etc.) with a multi-beam sounder.