Macromolecular labelling patterns and inorganic nutrient limitation of a North Atlantic spring bloom

Abstract

Synthesis rates of macromolecular classes (protein, polysaccharide, neutral lipid, glyco-lipid and phospholipid) were measured using 14C incorporation to assess the physiological condition of phytoplankton during a spring bloom in NE Sargasso Sea. The rate of protein synthesis at night was a small fraction (0-23%) of the day-time rate. Incubation irradiance and overnight metabolism had relatively little effect on total or class-specific lipid synthesis. Inorganic nutrients decreased to below analytical detection during the sampling period, with coincident declines in chlorophyll a concentrations. The changes in macromolecular labelling patterns were consistent with a physiological response to nutrient depletion by the phytoplankton, and a reduction of 50% or more in specific growth rates. -from Authors