Scattering and attenuation properties of Emiliania huxleyi cells and their detached coccoliths

Measurements of the spectral scattering and attenuation properties of coccolithophores ( Emiliania huxleyi ; clone 88E) and their associated coccoliths were made for three growth phases as well as for acidified cultures. These measurements allow a clean separation and determination of the optical effects of the various components. The beam attenuation cross sections (m 2 particle −1 ) were found to be 8.4E‐12, 2.6E‐10, and 4.9E‐11 for coccoliths, plated cells, and naked cells, respectively, at 440 nm. The spectral dependence of these factors followed a power law dependence, with a wavelength exponent of −1.9, 0.42, and −0.52 for the coccoliths, plated cells, and naked cells. The volume scattering functions for all appeared similar; however, the backscattering cross sections (m 2 particle −1 ) at 456 nm were 1.4E‐13, 6.7E‐12, and 9.9E‐13, respectively. The wavelength dependence of this parameter also followed a power law and was −1.4, −1.2, and −1.0. Overall, these results show that optical properties of a coccolithophore bloom are sensitive to the coccolith:cell ratio and can vary between and within blooms.