A new age of discovery

© C.Guigand

2013

The large-scale expeditions Tara Arctic (2006-2008) and Tara Oceans (2009-2012) were received with great acclaim by the scientific community.

In the science world, data collection is only the tip of the iceberg. Before a scientific article can be written the data is subjected to a long period of analysis, comparison and supplementary research. Much time is required between starting the research and finally making the findings « official » by publishing them. According to Éric Karsenti, research director at the CNRS (France’s National Centre for Research) and at the European Molecular Biology Laboratory (EMBL), this can take several years even for projects with a limited data collection phase. However for such large-scale projects as the Tara expeditions « operations take place on a completely scale », he says.

Tara Oceans gradually unveiling the secrets of plankton

It has been four years since the launch of this last expedition, involving the CNRS, the French Alternative Energies and Atomic Energy Commission and the EMBL, and already eight scientific articles have been published. This gives an idea of the huge amount of knowledge that it will be possible to draw from Tara Oceans. One of these articles, for example, reveals the relationship between certain viruses and other planktonic organisms. Éric Karsenti is particularly pleased with this work: « It’s the first publication to show how data from the Tara can be employed to explain interactions between different organisms. One of the aspects we were really keen to understand was what interacts with what in the ocean. » These initial results are exciting and concern just one of the many fields of research covered by the Tara Oceans project. Moreover this particular study only focused on seventeen of the samples collected during the expedition. In all, Tara Oceans brought back some 28,000 samples, which provides an indication of the wealth of findings to come. Other publications released in recent months include the explanation of a new method for analysing bacterial diversity in samples and the description of a new species of coral discovered in the Gambier Islands (Pacific Ocean). There is still an enormous amount of data analysis to be done, which explains why such articles have so far been limited to a few highly-specific topics. The sequencing of all of the samples alone is expected to take two to three years. « We are currently working on a publication on global and local diversity in eukaryotes*, how they differ from one region to another » says Éric Karsenti. « Another study due to be published comprises a global catalogue of bacterial genes ».

For the time being though people will have to settle for the preliminary results. Thanks to the Tara Oceans expedition there are now thought to be over a million species of protists**, whereas previous estimates considered there to be around 100,000. Sequencing performed on protist samples from twenty-eight of the 153 sampling stations revealed that eight-five per cent of them had previously unknown DNA sequences. In addition to the studies carried out by the Tara Oceans project teams, a whole host of further research may be started in coming years. One such project called Oceanomics*** is already underway. This project consists of structuring the thousands of samples and data collected during the Tara Oceans expedition to understand the nature and functioning of world the wide planktonic biodiversity and eventually extract certain bioactive planktonic compounds that show promise for, for example, biofuels and pharmaceutical applications.

The first data sets will be made available online to the scientific community by the end of the year. Éric Karsenti says: « It is without doubt the most signif icant achievement of an expedition like this. It is similar to a library where researchers the world over will be able to work on the Tara Oceans samples, and who knows what might be the result. »

Tara Arctic improving understanding for better forecasting

The Tara Arctic Drift of 2006 to 2008 has already led to the publication of over two dozen scientific publications. A substantial quantity of information has already been analysed, according to Jean-Claude Gascard, research director at the CNRS who was in charge of the scientific programme for Tara Arctic and of the DAMOCLES research programme: « The data collected during the expedition will serve as a reference on an Arctic system undergoing profound transformation and I wouldn’t be surprised if people are still publishing works based on this data ten years from now. » The first major result to come out of Tara Arctic concerned the drift process itself and this has led to several publications. The expedition was originally planned to take a thousand days, as the Fram had done over a century before. However the Tara completed the drift in just 500 days, demonstrating the increase in Arctic ice drift speed. Following this initial major finding, several works were published on the interactions of the three Arctic system components: ice, atmosphere and ocean. « The Tara has helped to highlight the formation of ice crystals, called Frazil ice, which rise to the surface », explains Jean-Claude Gascard. « The existence of this phenomenon in Antarctica was already well known, but we managed to show that it is a major phenomenon in the formation of Arctic ice too ». As regards atmosphere, research conducted aboard the polar schooner has helped to achieve a better definition of the lower Arctic atmosphere which is in contact with the ice and which is essential to air-ice interactions. « We had very little information on these lower levels which are difficult to study with satellites and automatic stations » Gascard says. « Indeed, the advantage of Tara Arctic is having people on board to operate instruments that we don’t yet know how to automate ». Finally, several publications have investigated ice sheet movements through the application of seismological techniques. All of the findings from the data collected during the Tara Arctic Drift will help achieve a better understanding of the complex Arctic system, and thus improve forecasting models. These it systems simulate the behaviour of the atmosphere, oceans and ice to provide short-term scenarios, ice charts and weather forecasts, as well as more long-term simulations which are crucial to research on climate change. Within the next few years conclusions drawn from Tara Arctic, in addition to other research, will be integrated into the various digital models to improve forecasting capacity. We are therefore already on track towards the first concrete applications of research conducted aboard the Tara.

Yann Chavance

Read this article on Tara’s 10 years journal

* : Single-celled or multicellular organisms that are characterized by the presence
of a nucleus.
** : Unicellular organisms with nuclei that are the ancestors of all forms of life.
Certain types are photosynthetic, such as diatoms.
*** : The Oceanomics project – wOrld oCEAN biOresources, biotechnology,
and earth-systeM servICeS – won the French government’s ‘Investments