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An ocean of genetic data, molecular, physical, chemical, microphotographic … Fishing plankton carried by the sailboat Tara between 2009 and 2013, on all the seas of the globe, coming off his first scientific translation, along with the joint publication of articles in several prestigious journals, including journal Science, Friday, May 22 An end to the international consortium Tara Oceans, involving teams of researchers to seamen of the Tara Foundation, which has chosen to make his famous schooner an oceanographic research vessel in itself, together with a standard defense . sea
The expedition has sought to describe all facets of an unknown world, almost invisible. plankton “The plankton is more than food for whales , describes Chris Bowler (ENS, Inserm, CNRS). These microorganisms are the basis of the entire ocean food chain, but also mechanisms that affect the entire planet, as the carbon cycle. “ They represent 80% of the biomass of the oceans, through photosynthesis and produce half the oxygen we breathe.
Tara is certainly not the only shipment of this nature in the twenty th century, but this is one of the most ambitious. It aimed much further, for example, as the Sorcerer II , sailfish US geneticist Craig Venter, a pioneer of fishing genomes in the late 2000s ‘C’ was still the beginning of metagenomics, the study of the genomes of a community of organisms, and Venter has focused mainly bacteria, says Eric Karsenti (EMBL Heidelberg, CNRS), Director of Tara Oceans. Our aim was to correlate the complexity of planktonic life and the environment in which it operates. “
The team members of Tara have therefore risen in their nets viruses, bacteria, protists – of mostly single-celled organisms, nor animals nor plants – harvested mainly in the first 200 meters deep, and up to 1,000 meters. Their mesh could remember any living being of a size ranging from 0.02 microns to several millimeters. The team collected a total of 35,000 samples in 210 sites.
“The composition of the different microbial communities was mainly dependent on the water temperature”
One of the objectives was to describe the genes of some of these tiny inhabitants of the seas – mainly bacteria, relatively simple genomes. At Genoscope Evry (CEA), the screen DNA sequencers sifted over 40 million genes, mostly new to science. The analysis of more than 35 000 species of prokaryotes (organisms without a nucleus of cell) showed their distribution in different communities, “whose composition was largely dependent on the water temperature” says Shinichi Sunagawa (EMBL), who discovered the primacy of this factor is of great importance, as the planet is experiencing a warming that also affects the oceans. “It will take more data to know what will happen to these ecosystems to climate change” , he says
Another surprise. The analysis of the functions of these genes shows that 73% of them are also represented in the human intestinal flora (microbiota), “despite the physicochemical differences between the two ecosystems” .
The mode of interaction between the multitude of marine organisms is also unexpected. “For most, collaboration is more important than competition , says Eric Karsenti. This is a very important result because it could change a bit the way one usually considers the development, with the idea that it is controlled by the survival of the fittest. “” The marine ecosystem is not like a forest with its classic pyramidal food chain, where the carnivore eats the herbivore, bounces Chris Bowler. There are a number of organizations, parasitic or symbiotic, that provide other services, such as recycling. “
"M Ormestad / Kahikai / Tara Oceans." "lmd.pic (this);" onerror = "lmd.pic (this);" class = "lazy-retina" /> Another lesson shipment has probably garnered the bulk of planctonienne ocean biodiversity – in their beds. superficial, at least. “ We found a high level of saturation in our genetic data , says Chris Bowler. This is to say that each additional sample revealed new genes at the margin. “
This does not mean that the search started is completed. Genetic analysis is still in its infancy: while each body recovered was observed microscopically and duly photographed – offering a huge album, as varied aesthetic – the work to be done to connect the DNA sequences to their rightful owners, as photogenic as they are. Chris Bowler, the availability of data and its exploitation by other teams give the true measure of the seed of Tara Oceans.
The preparatory phase – the one we saw little – had been long. “The development of the scientific project took a year and a half, Romain testifies Troubled, the secretary general of the organization. The debates were lively early between oceanographers, which are rather physicists and biologists. Being able to make out each of his laboratory is our added value. “
The next mission dedicated to corals in the Pacific looks just as demanding in terms of interdisciplinarity. What would be the most sensible approach to bring new knowledge on this subject? Experts involved in the debate for months. The guidelines are not yet finalized and the departure will not take place within a year.
However, the challenges do not take as scientific, Tara is also, and even above all, a human adventure. At sea, the exploit lies in the everyday coexistence on a boat 36 meters long cluttered equipment. In each mission, rub shoulders six or seven researchers at work, as many sailors, artists at times, a journalist … all amid boxes of samples must stored at a temperature of minus 18 degrees – regardless latitudes -., landed every three months to make room
“ There are great ” Biodiversity “ to Tara Troubled Roman smiled. Two-hundred and thirty scientists from 35 or 36 different nationalities have succeeded . Whenever we approached the coast of a country, we invited local researchers to join us. The work done on board, day and night, with powerful devices, some of our guests saw this as science fiction! “
Navigate around the globe is not done without thrills. In the Gulf of Aden, the expedition received the backing of the French army to deter pirates. In the Maldives, it was necessary to change course in order not to deal with. There were gales in Antarctica, a large unexpected storm in the Mediterranean Sea, a broken anchor, setbacks – a blocking week in ice passage Northeast …
Ashore The company Tara is not easy either between logistics, financing, the enthusiasm of patrons must be maintained, legal aspects, etc. “ To collect plankton in twenty different EEZs, you have to book months in advance, obtain support from the embassies’ reports the General Secretary. Have they suffered rejection? India and Saudi Arabia have not replied, Ecuador has not cleared in time.
The schooner there has yet stopped. Troubled by Romain fond memories. “ 2,500 uniformed schoolchildren gathered in an airport lobby which we explained the impact of the health of oceans on climate, it had upset me. ” The expedition n ‘ Never forget the first mission it had set to debut in 2003: testify and advocate for the marine ecosystem
Also, in the adventure of Tara, discussion board with. UN Secretary General Ban Ki-moon in New York in 2012, she was an important moment. The welcome, always friendly, in the port of Lorient, her home port, rest him, as the emotion sequence.
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