Last may 2025, the French polar patrol vessel L’Astrolabe set sail on a sovereignty mission to the French Southern and Antarctic Lands (TAAF) — a vast, remote territory in the sub-Antarctic region.

To reach these isolated islands, the ship had to navigate through the Roaring Forties and confront the Furious Fifties — notorious latitudes known for their harsh maritime conditions, including 3°C waters, 10-meter waves, and winds exceeding 75 knots.

Romain Persat from the Mission de Bougainville is a scientific initiative that studies the planktonic biodiversity of the Pacific, Indian, and Southern Oceans, using low-cost, field-ready instruments deployed aboard French Navy vessels.

The Southern Ocean, a key regulator of the global climate, supports an exceptional marine microbiome despite its extreme conditions. During the mission, Romain conducted eight plankton samplings — both during navigation between island districts and in several sites within Morbihan Bay in the Kerguelen archipelago. These samples highlighted the vibrant, microscopic life flourishing in the nutrient-rich cold waters of the Southern Ocean.

Onboard, the Curiosity microscope was used for both scientific analysis and science communication. It enabled real-time visualization of collected samples, offering a quick overview of plankton abundance and concentration prior to quantitative imaging. It also served as a powerful tool to engage the ship’s crew and the overwintering scientists at Port-aux-Français, helping to explain the Bougainville mission’s goals and the ecological importance of plankton in the ocean.