log book - Tara’s Summer
From June through August, Tara will be sailing around French Polynesia, making a mission to study coral reefs in the Gambier Islands and a mission employing a glider (remote-controlled submarine) in the Marquesas Islands.
Study on coral reefs in the Gambier Islands
A mission to study corals will take place in the Gambier Islands from June 25 to July 10. 30 dives (2 per day) are programmed. Besides studying the biodiversity of the Gambier corals, this mission aims to expand and complete our knowledge about Indo-Pacific coral reefs in the context of climate change. This study follows those carried out by Tara at Djibouti, Saint Brandon (Maurice) and Mayotte in 2010.
This mission will be directed by Francesca Benzoni, who coordinates Tara’s coral reef studies and is a scientist at the Research Institute for Development (IRD) in Nouméa.
It’s the first time that coral studies will be correlated with plankton analysis during the Tara Ocean Expedition. The scientific consortium hopes to establish the links between coral reef life and planktonic organisms.
Why is it interesting to do this study in the Gambier Islands?
by Michel Pichon, Tropical Marine Consultant
“Contrary to the Marquesas Archipelago, the Gambier Islands have been the object of only a very limited number of expeditions and scientific studies, partly due to their relative isolation. With respect to Scleractinia (stony corals) and coral reefs, the only available publication (by Chevalier), dates back to 1974, when missions were carried out by the MNHN (National Museum of Natural History) under contract with DIRCEN (Direction Center for Nuclear Experiments). In his publication, Chevalier mentioned (after synonyms were updated) the presence of 54 Scleractinia and Zooxanthella species. This number is abnormally low, in comparison to the number of species found in other zones and localities of the region.
Gambier’s coral fauna is strikingly less abundant than that of Mururoa, and approximately the same quantity as found at Pitcairn, even though Gambier is situated more to the east and above all more to the south (250 04’ S). This situation is not consistent with biogeographic considerations, which suggest that the Gambier coral fauna in particular should be significantly more diversified than that of Pitcairn. Especially since the morphological diversity of Gambier coral structures (fringing reefs, emerging barrier reefs, submerged barriers, lagoon formations) is in itself a factor in species diversification (due to the many different types of milieu). Probably the apparent lack of coral diversity is an anomaly resulting from very insufficient sampling. Although the authorities were informed of this situation, no initiative to rectify it has been made until now. To summarize: our knowledge about Gambier coral fauna is very incomplete, and more research needs to be done concerning the biodiversity and the biogeography of the Scleractinia.”
Stopover at Mangareva (Gambier Islands), June 22-25 and July 10-13.
Mission employing a glider in the Marquesas Islands
A mission employing a glider (remote-controlled submarine) and drift buoys is programmed for the open sea surrounding the Marquesas Islands, lasting 12 days beginning on July 24. The goal is to characterize the prevailing planktonic ecosystem under the influence of island winds. The zone is located in a phytoplankton “bloom”. The glider and drift buoys record the physico-chemical data of the water, while the team aboard Tara receives the information in real-time, resulting in a 3-D cartographic rendering, and subsequently biological sampling will take place at the most pertinent locations. Another operational buoy (Provbio) will take vertical sampling in the water column to help characterize the sampled water.
This mission is co-directed by Fabrice Not (scientific coordinator of Tara Oceans) from the Biology Station in Roscoff (CNRS-UPMC), Daniele Iudicone (also scientific coordinator of Tara Oceans) from the Stazione Zoologica in Naples, and Fabrizio d’Ortenzio from the Oceanography Laboratory in Villefranche sur Mer (CNRS-UPMC). The mission is a collaboration between the LOCEAN Laboratory in Paris, the Ecole Normale Supérieure (ENS) in Paris, the French Research Institute for Exploration of the Sea (IFREMER) and the Insular Research Center and Environment Observatory (CRIOBE) in Moorea, French Polynesia.
Stopover at Taiohae (Marquesas Islands), July 21-24.