DISTRIBUTION PATTERN OF COCCOLITHOPHORID BLOOMS IN THE WESTERN NORTH-ATLANTIC OCEAN

The temporal and spatial distribution patterns of coccolithophorid blooms in surface waters of the western North Atlantic (40 degrees W-75 degrees W, 40 degrees N-60 degrees N) from 1979 to 1986 were determined by recording the presence of these blooms through visual examination and supervised computer classification of atmospherically-corrected visible Nimbus-7/Coastal Zone Color Scanner imagery. In addition to the previously documented occurrence of satellite detected coccolithophorid blooms on the continental U.S. shelf and in the Gulf of Maine, large expanses of spectral characteristics unique to these blooms were also consistently observed in surface waters of the Scotian Shelf and Slope, the Gulf of St Lawrence, the Grand Banks and the shelf off northeastern Newfoundland and southeastern Labrador. Blooms were observed in the western North Atlantic from mid-May to early November, achieving their greatest total areal extent in August. Blooms annually covered an average of 300,000 km(2), yet this value is probably an underestimate due to restricted Visibility of the sea-surface caused by both clouds and incomplete imagery coverage. The magnitude and periodicity of coccolithophorid blooms demonstrate their importance as an episodic source of CaCO3-carbon and of dimethyl sulfide-sulfur to the western North Atlantic.