85,000 litres of seawater for science

A month and a half ago I embarked aboard Tara at Wallis, the most distant place from Paris I’ve ever traveled.

[After finishing her thesis on data from the Tara Oceans expedition in Chris Bowler’s lab at ENS d’Ulm, Flora Vincent embarked on Tara for the first time at Wallis to sample plankton during the Tara Pacific expedition. She will debark at Fukuoka, JAPAN. ]

Scientist Flora Vincent shaking her 1,801 sample bottle of this leg of the expedition © Sarah Fretwell / Fondation Tara Expéditions 

I had just finished my PhD at the Ecole Normale Supérieure (Paris) in Chris Bowler’s laboratory, where I was working for 3 years on data collected during the Tara Oceans expedition. As incredible as it may seem, one can do an entire thesis based on the data from Tara Oceans and never have embarked on the schooner. So quite naturally when Colomban de Vargas and Sarah Romac – responsible for plankton research on Tara Pacific – proposed that I come aboard to collect plankton between Wallis and Fukuoka, I jumped at the opportunity.

The majority of scientists aboard Tara are busy analyzing coral, but Guillaume (the bridge engineer) and I are interested in everything that happens around the coral. What are the physico-chemical parameters of the surrounding water? Which micro-organisms invisible to the naked eye populate the reef? What do they do and how are they different from the ones we find directly on the corals or further out to sea? What is the influence of an island and its population in the middle of the Pacific on the planktonic ecosystem?

Concretely our scientific work is divided into 2 stages. There’s the so-called ‘island phase’: twice a day I go on a zodiac to collect seawater near the coral reefs with the help of the crew – often Julie, Nico, Martin and Jon. Once we’re back on Tara, we do a battery of genetic, morphological and physico-chemical analyses. I had a chance to take samples from the Tuvalus, the Kiribati, Chuuk, Guam and Ogasawara – exceptional places that before I could hardly have pinpointed on a map – unfortunately now threatened by climate change.

Tara scientists Guillaume Bourdin and Flora Vinent confer over sample results during their nigh time sample © Sarah Fretwell / Fondation Tara Expéditions

Between 2 islands is the so-called ‘Ocean phase’. During daily voyages in the open sea, Guillaume and I collect water directly as the boat advances, thanks to a series of nets, pumps, and pipes which we put into the water at precise places of interest, with the help of the sailors, by day or by night, in the sun or rain. Afterwards we perform all the manipulations necessary to harvest the micro-organisms present in the water.

This experience in the field is exhilarating: from the 85,000 liters of seawater we collected in just 2 months (of a 2-year expedition!), several years of research and new discoveries will result. Thanks to Tara we can develop approaches and answer questions that only such a large scale of sampling and interdisciplinarity allow. My adventure on board will soon be over, but for Tara Pacific, it’s just the beginning.

Flora Vincent