Flow cytometric determinations of North Sea phytoplankton optical properties

Abstract The optical properties of North Sea phytoplankton (refractive index and fluorescence-specific scattering) were measured using flow cytometry in July 1987 during a research cruise sponsored by the Plymouth Marine Laboratory and the Environmental Research Council of the UK. Refractive index and associated size distributions of chlorophyll-containing cells were quite broad and did not provide unique descriptions of North Sea water masses. Fluorescence-specific scattering was found to increase within northern and central North Sea waters. AVHRR channel 1 data from satellite overpasses prior to and during the initial stages of the cruise indicate that a large coccolithophore bloom was developing within the northern portion of the North Sea and within Norwegian coastal waters. This bloom may account for the large values of fluorescence-specific scattering.