Ocean colour observations show considerable variations across the South Pacific: one vast blue spot is roughly centred on Easter Island, covering an area equivalent to the Mediterranean Sea. Standing like an oasis in these blue desert waters is the chlorophyll-rich zone around the Marquises Archipelago, the precise reason for its fertility still uncertain.
And just off the west coast of Chile is an upwelling of cold, nutrient-high water that supports extremely dense chlorophyll concentrations and one of the most important fisheries on Earth.
Setting off from Tahiti in mid October, the BIOSOPE (Biogeochemistry and Optics South Pacific Experiment) research cruise recently traversed this entire area, reaching Concepcion in Chile in mid-December. During two months aboard L'Atalante, a 45-strong international team of researchers investigated the determining factors of ocean colour.
"The region's wide variety of ocean colour and trophic regimes in other words, biological activities initially triggered by phytoplankton - is the reason we decided to carry out our study here," explained project scientist Herv Claustre of the Observatoire Ocanologique de Villefranche, present on the cruise alongside colleague Andre Morel.
"Ocean colour satellite imagery has been of great help when planning the cruise, and throughout the field campaign. The information allowed the course of the ship to be adjusted according to the desired chlorophyll concentration, and was especially useful when the ship sailed within the complex and patchy zone of
Contact: Mariangela D'Acunto
European Space Agency