It's time for biology

Operations started soon after our arrival at TAG on Friday with two dives on Mount Abyss and one on Active Mound.

Erwan’s first dive was to explore and sample both fauna and rocks from fossil hydrothermal fields. Samples of pressurized fluids were collected with the IBIS sampler. These samples will allow Erwan to study the microorganisms living on these fossil sites.

Experimental colonizers called DEEPSEEDS were dispersed. These are colonization surfaces connected to mini particle traps that will monitor the installation of the organisms. These colonizers will be recovered during BICOSE3. Temperature measurements have shown that these sites, although they are old, are not yet fossils! Some still exhibit slight fluid activity with temperatures up to 17°C and the presence of microbial mats.

The next day it was Valérie’s turn to go down to Active Mound for a shrimp party. More DEEPSEEDS were deposited, fluid samples and temperature measurements were also made at different spots of the TAG field. Samples of the shrimp populations were also made. The objective of this dive was also to study the distribution of fauna on Active Mound in the summer with a focus on the shrimp Rimicaris exoculata. The shrimp were collected with the FISH sampler and recovered with the aspirator on the Nautile. Another species of shrimp, Rimicaris chacei living alongside Rimicaris exoculata were also collected.

Back on the ship, some of the shrimp were dissected by Marie-Anne, while Florence and Valérie began sorting the shrimp for a second time to measure and count males and females.