© Yann Chavance / Fondation Tara Expéditions

27 September 2016

Island after Island, Tara continues her course across the Pacific Ocean. This week, the vessel stopped in the Gambier Archipelago in French Polynesia. The schooner’s route draws a straight line from South America to Japan: a crossing from East to West, particularly interesting for scientists.

After the Panama Canal, gateway to the Pacific, and Malpelo, the Colombian interlude, the route to the West began in Rapa Nui (Easter Island), then continued to Ducie Island, and now to the Gambier Islands. Later on the schooner will pursue this path and sail towards Tahiti, Samoa, Wallis and Futuna, the Marianas and other islands, before arriving in Japan in February 2017. As a result, Tara keeps crossing time zones: since our departure from Easter Island, we have already changed the time 4 times, stretching days to 25 hours. And it’s not about to stop: when Tara arrives in Japan, the vessel will have crossed about 15 time zones since her departure from Lorient.

The schooner is heading towards a mooring site, safe from strong winds and waves, in Taravai, the second largest island of the Gambier Archipelago © Yann Chavance / Tara Expeditions Foundation

Besides this race against the setting Sun, the route to the West presents a real scientific interest. « Pacific coral reefs have a very strong biodiversity gradient from East to West», explains Emilie Boissin, one of the scientific coordinators of the expedition. «The further West we go, the richer the reefs will get in terms of species diversity.» A statement already verified by the first divers’ observations: in Rapa Nui, the sea floor showed mainly 2 species of coral. In Ducie Island, the number of species had already increased and here, in the Gambier Archipelago, the first dive seemed to confirm even greater biodiversity.

The relative barrenness of the first islands visited has forced scientists to lower their ambitions: of the 3 coral species studied during the expedition, only 2 were observed in Rapa Nui and Ducie Island. The same is true for the 2 kinds of fish targeted: none was found in Rapa Nui and only one in Ducie Island. But, according to scientists on board, everything should change now: if all goes well, this stopover in the Gambier Islands should finally lead to the observation of all study subjects. Even in the absence of some species, this crossing from East to West is still very interesting. «We are studying the coral microbiome, all microorganisms living with corals», describes Emilie Boissin (CRIOBE). «One of the important questions is whether this microbiome also follows the same biodiversity gradient from East to West». Part of the answer surely lies within the thousands of samples in Tara’s fridges.

Yann Chavance

Related articles