Representatives from the 12 partner laboratories of Tara Mediterranean met a few days ago at the Oceanographic Observatory of Villefranche-sur-Mer. A productive seminar allowed scientists to review the mission, redefine their expectations and identify tasks to accomplish in the coming months. Maria-Luiza Pedrotti, CNRS researcher and scientific coordinator of Tara Mediterranean, was present. She tells us about these 2 days of exchanges:
Why did Tara Mediterranean scientists recently meet?
We had completed the phases of acquisition and sorting of samples. For several months samples were annotated, we organized the tubes and their metadata, and drew maps indicating origins of samples. It was time to bring together all the participants of the mission to set up working groups for the analysis phase which starts in April.
Each sample will be analyzed in partner laboratories according to their expertise. Technicians will separate plastic from plankton. The pieces of plastic will then be counted, weighed and classified according to their type. Engineers and students will scan these fragments to collect data on their size and shape. Part of the plastic will be sent to laboratories that will conduct chemical analysis to determine the origin of the plastic, and measure the amount of associated pollutants. Other samples will be used in genetic studies. Powerful microscopes will identify species that colonized these particles. The plankton itself will be sent to specialists for taxonomic determination.
The consortium has allowed us to define protocols and a hierarchy of analysis (first separating samples, counting, etc.) as well as a work-flow for samples and data.
What observations have been made at this stage of the research?
The work to date demonstrates the importance of plastic fragments in the surface ecosystem. Our samples will allow us to shed light on the quantity of fragments, their size spectrum, potential interaction with living organisms, and their surface distribution in the Mediterranean basin. Micro-plastics are present in all of our samples, but their distribution is heterogeneous. We will therefore determine the different aggregation zones of these particles.
Images acquired aboard Tara Mediterranean show a great diversity of fragments to which populations of living organisms are attached. These micro-plastics can therefore serve as vehicles for certain toxic or invasive organisms.
What’s next for Tara Mediterranean and its researchers?
The scientific partners will perform the biological, chemical and physical analyses of samples to build a multidisciplinary database and prepare scientific publications. At the same time, they will submit research projects to find funding to complete certain analyses.
Interview by Noëlie Pansiot