Satellite detected cyanobacteria bloom in the southwestern tropical Pacific Implication for oceanic nitrogen fixation

Abstract
Tropical seas are major sites for extensive cyanobacterial ( = blue-green algal) developments. The oceanic nitrogen fixation caused by such blooms may be of relatively great importance in regard to the global nitrogen budget. A Nimbus-7 Coastal Zone Colour Scanner (CZCS) image on 4 January 1982 shows a large phytoplankton bloom (90000 km2) around New Caledonia and the Vanuatu archipelago, located east of Australia in the Coral Sea (165° E, 20° S). The bloom is caused by cyanobacteria, presumably Oscillatoria (=Trichodesmium) spp. which occur systematically in this region. This assertion was not controlled by simultaneous sea-truths, but several indices and current knowledge of the region indicate that our hypothesis is reasonable. By using the CZCS image, an estimation is made for the nitrogen fixation of the bloom. It suggests that such a biological event plays a significant role in the global nitrogen oceanic budget.