DISTRIBUTIONS OF CHLOROPHYLL AND PRIMARY PRODUCTIVITY IN RELATION TO WATER COLUMN STRUCTURE IN THE EASTERN NORTH ATLANTIC OCEAN

Latitudinal variations in the megascale (103 km) distribution of biological properties are described in relation to water column structure between 60 degrees and 7 degrees N in the eastern North Atlantic Ocean. Stations were occupied along a meridional transect of stations at 20 degrees W in August-September, 1988, during the third leg of the National Oceanic and Atmospheric Administration Global Change Expedition. An additional transect to the south (38 degrees N to 7 degrees N) was occupied to extend the total range of latitudinal observations. Chlorophyll a concentrations were highest in the northern latitudes (<2.51 mg m(-3)), decreasing to >0.2 mg m-3 in the vicintiy of the subtropical gyre, south of 40 degrees N. The nitracline was associated with a shoaling of the pycnocline in the northern latitudes. At 7 degrees N, high chlorophyll concentrations (approximately 0.5 mg m(-3)), and enhanced primary productivity (375.5 mg C m(-2) d(-1)) were associated with a lens of fresh Amazon River Water. Primary productivity rates were variable throughout the transect, ranging from 646.10 mg C m(-2) d(-1) to 138.26 mg C m(-2) d(-1). Productivity maxima were located south of Iceland, at 46 degrees N (646.10 mg C m(-2) d(-1)) and in the vicinity of the Azores Front at 35 degrees N (259.85 mg C m(-2) d(-1)). Latitudinal distributions of primary productivity corresponded closely to a model of productivity along a transect at 40 degrees N by Yentsch (1990)