Seasonal variaion of nutrients and suspended biomass on a transact across Nordvestbasken, north Norwegian shelf, in 1994

Abstract

Abstract Nutrient consumption in the uppermost, well-mixed 100m of Nordvestbanken in 1994 started in March across the entire shelf. Significant nitrate reduction in the euphotic zone was reached in June at the inner and middle shelf, but not until September at the shelf edge. The variations of nutrient concentrations were generally similar for nitrate, silicate and phosphate. Increased stratification, giving rise to a pronounced nutricline around 40 m depth, was observed from August to October at the shelf edge., but not on the middle and inner shelf. The maximum carbon equivalent of cumulative nitrate consumption in the upper I 00 mat the inner, middle and outer shelf was about 72, 52, and 55 g C m-2 and occurred in June, August, and July, respectively. The suspended chlorophyll a concentrations were generally low throughout the transect and observed in June and July. Suspended phacopigment concentrations were generally lower than 1 mg m-2 The concentration of suspended organic carbon was moderately high...