Tara Microbiome expedition: two years to understand the ocean
Audio 02:30
The Tara Microbiome expedition set sail on Saturday, December 12.
© RFI / Agnès Rougier
By: Agnès Rougier
11 min
The 11th expedition of the scientific schooner Tara, which left Lorient on the anniversary of the Paris Climate Agreement, focuses on the microbiome.
How does this invisible little people of the oceans react to global warming?
This is one of the questions scientists intend to answer over the next two years.
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The ocean, a complex and unknown organism
On our skin, in our intestine, microbes - bacteria, viruses, protists - are everywhere present, they form a whole called microbiota, which lives in symbiosis with humans.
Not all microbes are harmful, like that of the coronavirus, most of those who are our companions help us on the contrary, they are the guarantors of our good health and our well-being.
But when this invisible fauna is unhealthy, so are we.
In the ocean, microorganisms composed of a single cell, measuring less than a millimeter, together also make up the ocean microbiome.
This microbiome also includes phytoplankton which performs photosynthesis, it is responsible for half of the oxygen we breathe and for a third of the global absorption of greenhouse gases.
That he stays in good health is therefore fundamental, and it is necessary to understand how he is reacting today to climate change.
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To read also:
Departure of the Tara mission, a 2-year scientific expedition in the Atlantic
Understand how it works
The Tara Oceans and Tara Méditerranée expeditions successively sampled oceanic plankton and then microplastics in the Mediterranean.
Tara Oceans provided the first inventory of the oceans and the first database of ocean microorganisms.
Tara Microbiome is now interested in the functioning of this small people in its ecosystem.
Sampling and data collection will cover all the biological, physical and chemical characteristics - identification of organisms, temperature, presence of metals, plastic pollution, etc. - breaking down the ecosystem with the objective of finding the indicators that will make it possible to diagnose the health of the ocean.
Chris Bowler, scientific co-director of Tara Expeditions: “
We are interested in both microbes and the theater of their activities.
(…) There are in particular the plastic fragments that are part of it.
"Because in 50 years, since plastic invaded the oceans, microbes have evolved and they are now able to break it down.
It would therefore be very interesting to understand this process in order to use it to remove plastic at sea.
Two years of expedition, 70,000 km, 22 stopovers
The trip will be punctuated by sampling stations planned on sites that would seem interesting: at the interfaces between the flow of the great rivers - the Amazon, the Congo and three other African rivers - and the ocean, but also in the Weddell Sea (Antarctica ), irrigated by melting glaciers, and in upwellings, these vertical currents which bring up to the surface cold waters very rich in nutrients.
Tara Expeditions card, Microbiome mission.
© Tara Expeditions
After passing through Cape Verde, Tara will begin the two-month crossing to Chile, the first major stage of the mission.
Then, most of the trip will take place in the South Atlantic and, for the first time, Tara will go up the African coasts, from Namibia to Senegal, one of the most productive marine regions in the world.
Two captains will be at the helm on a three-month shift: Martin Hertau and Samuel Audrain.
The navigation could prove to be complicated, as the schooner foresees a long passage with sampling stations in the howling fiftieths, known for their raging seas.
A vast scientific project
The expedition's collection tools are the Manta net, dragged on the surface as the boat moves forward, the rosette, intended to sample the water and measure the physical parameters at different depths, and plankton nets.
On board, thanks to the miniaturization of the equipment, a third laboratory could be installed instead of a cabin, to complete the two laboratories already present - a wet laboratory on the aft deck, intended for the filtration of water for separate viruses and bacteria, a dry laboratory inside where the temperature and pressure constants arrive.
This third laboratory will be devoted to the real-time analysis of chlorophyll and acidification.
In line with previous expeditions, work in collaboration with the Génoscope d'Évry will continue, the idea being to sequence the genomes discovered and to list them, while trying to bring them together in the spirit of a "metagenome" representing the microbiome as a unique being.
A total of 80 researchers will take turns on board, and 200 scientists from 42 institutions in 13 countries will work on the data collected.
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Also to listen:
The schooner Tara takes to the sea to understand the invisible people of the ocean
Stay optimistic despite the crisis
The departure of the expedition had to be postponed three times due to the health crisis, but that's it, they left, and Clémentine Moulin, the logistician of Tara Expeditions for five years, does not hide her joy!
In principle, the logistics are worked out six or eight months in advance, but the Covid-19 epidemic has upset the timings and despite the anticipation, everything must be reviewed in real time.
From the Tara base in Paris, Clémentine takes care of contacting the ports as the boat advances to find a docking pontoon and manage health protocols, she also organizes crew rotations (14 to total, including six scientists, six sailors, a journalist and an artist) and manages the shipment of equipment and supplies.
The Covid protocol on board is very strict: crew members arrive only by plane, going directly from the airport to the boat: "
We are lucky to be able to carry out quarantines on board, because in the merchant navy, they have to do it at the hotel for 15 days.
(…) We are doing as everything was going well, we will adapt according to the evolution of the crisis locally.
"
But the crisis has a positive side: the waiting time made it possible to completely overhaul the schooner, the engines are new and Tara set out to sea on Saturday, December 12, deploying her brand new sails.
Good luck, Tara!
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Useful links:
Tara expeditions
Partner laboratories
Arctic Tara Expedition
Listening to Tara
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