“We have no discovery to reveal to you today (Saturday)”, immediately warned Romain Troublé, director of the Tara Foundation, during a press conference on the island of Groix.

After almost two years of the “Microbiome” mission, the famous sailboat-laboratory made a stopover on the Breton island before heading to Lorient, its home port.

Escorted by an armada of several dozen sailboats, Tara was acclaimed by a large audience who came to welcome her on the quays of Lorient on Saturday afternoon.

During its journey from Chile to Africa, via the Amazon and Antarctica, the boat designed by explorer Jean-Louis Etienne took nearly 25,000 samples of marine microorganisms (viruses, bacteria, prostites, animals, etc.).

“All this data will be analyzed. Within 18 months to two years, we will begin to have the first discoveries from this mission because while we are at sea, there are 300 researchers working,” said Mr. Troublé. .

At the base of the food chain, these micro-organisms, “invisible people of the sea”, constitute more than two thirds of the marine biomass. They capture atmospheric CO2 and provide half of the oxygen we breathe.

“The question we ask ourselves is: how does it work? How do all these viruses, these bacteria, these marine microalgae manage to interact to produce oxygen, store carbon and produce proteins?”, explained Roman Troubled. “And how will it change tomorrow with climate change and pollution?”

– Sargassum and plastic pollution –

The schooner was particularly interested in the impact of the Amazon River, whose flow is around 200 million liters per second, on the life of the ocean microbiome.

“We think that the Amazon has a role in the development of sargassum,” noted Samuel Chaffront, CNRS researcher at Nantes University.

These algae, which proliferate in the West Indies, give off foul and toxic fumes when they rot on the shore.

“One of the hypotheses is that Brazil’s deforestation and increasing agriculture have increased the discharge of nitrate fertilizer into the Amazon,” Chaffront said. “This can allow the development of these sargassum which are invasive species and which are found as far as the African coasts”.

The data collected by Tara during her previous missions gave rise to more than 250 publications in the scientific press. The role of plastic pollution has also been studied during the 22 months since his departure on December 12, 2020, in the midst of a health crisis.

“It’s a small ecosystem that happens on each piece of plastic in the oceans,” explained Jean-François Ghiglione, CNRS research director at the microbial oceanography laboratory in Banyuls-sur-Mer (Pyrénées-Orientales). “We want to see if the pathogenic microorganisms that live on these little plastic rafts will go for a walk in the oceans,” he added.

The 36 m long and 10 m wide schooner, with several laboratories on board, accommodates 14 people, including half a dozen scientists of all nationalities. The latter took turns on several occasions according to their research subjects.

Each part of the mission has been named after a female scientist “to honor” these researchers, said Flora Vincent, team leader at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany.

“Tara is emblematic of a scientific tool that combines cutting-edge research (…) and the words of scientists at the service of society. There is no finer example”, welcomed the Minister of Research Sylvie Retailleau, during a press briefing.

After several months in dry dock, the schooner will cast off again in the spring of 2023 for a new mission on chemical pollution off the European coast.