Surface chlorophyll a concentration in the global ocean.
Rosette used to collect seawater samples during a scientific cruise in the South Pacific Ocean. Duringthe austral summer,the amount of chlorophyllais so low thatthe water becomesdeepblue,almostpurple. (Photo : Joséphine Ras)
Average chlorophyll concentration in the surface ocean (from mi-September 1997 to August 2007) from the ocean color sensor SeaWiFS (NASA). Subtropical gyres, in the center of the oceanic basins, are characterized by very low concentrations of chlorophyll a (dark blue) - Source : NASA's Earth Observatory (http:/earthobservatory.nasa.gov)
World ocean currents map
Dinoflagellés Ceratium massiliense var protuberans (Photo : Sophie Marro)
Satellite observation (GEOS-12) of Hurricane Katrina in August 2005 in the Gulf of Mexico - Source : NASA-NOAA
Diatoms - Life in glass houses Champions of photosynthesis, these unicellular organisms appeared at the time of dinosaurs.They produce a quarter of the oxygen we breathe.