TONGA 2019
Type | Oceanographic cruise |
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Ship | L'Atalante |
Ship owner | Ifremer |
Dates | 31/10/2019 - 05/12/2019 |
Chief scientist(s) | GUIEU Cécile , BONNET Sophie |
LABORATOIRE D'OCÉANOGRAPHIE DE VILLEFRANCHE-SUR-MER - UMR 7093 181 chemin du Lazaret 06230 Villefranche-sur-Mer +33 (0)4 93 76 38 13 |
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DOI | 10.17600/18000884 |
Objective | The objectives of the cruise were to investigate at least 2 active volcanoes where shallow (< 500 m) hydrothermal sites could release chemical elements both able to fertilize and/or bring toxicity to the planktonic food web. More specifically, the task 1 of the TONGA cruise was to characterize chemically and optically the hydrothermal fluids and to compare the source from below (shallow hydrothermal fluids) with the source from above (atmospheric deposition); the task 2 was related to the dynamical dispersion of the fluids at small and regional scale; the third task was to investigate the impact of the shallow hydrothermal sources on the biological activity and diversity, and the feedback to the atmosphere via the oceanic emissions of primary and secondary aerosols. An important objective was to communicate about the campaign mainly by the feed of a Tweeter account (https://twitter.com/tongaproject). The outreach component of the campaign was done in collaboration with the adopt-a-float project https://twitter.com/AdoptaFloat) and two floats have been `adopted' by kids from two schools (one in Nouméa and one in Abu Dhabi). The position of the sampling station has been constantly re evaluated during the campaign to fulfill the objectives: a long west to east (up to the blue waters of the gyre) transect allowed to characterize the different biogeochemical provinces crossed and a focus in the region of the Lau Basin allowed to investigate the impact of shallow hydrothermal sources. A series of short and long stations allowed to fully characterizing the stocks and the fluxes in the different provinces. Short-term (up to 10 days) processes studies have been conducted (drifting moorings and minicosms experiments). A fixed mooring deployed in the Lau Basin will allow to study the carbon/metals export at the annual time scale. In addition to the team embarked on board the R/V Atalante, several scientists assisted us on land to advice on the potential active sites that we could visit, the dynamic condition of the targeted area and also specifically on the interpretation of acoustic survey above volcanoes.
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