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 c occoliths were made for three growth phases as well as for acidified c ultures. These measurements allow a clean separation and determination of the optical effects of the various components. The beam attenuatio n 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, respectiv ely, at 440 nm. The spectral dependence of these factors followed a po wer law dependence, with a wavelength exponent of -1.9, 0.42, and -0.5 2 for the coccoliths, plated cells, and naked cells. The volume scatte ring functions for all appeared similar; however, the backscattering c ross 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 al so followed a power law and was -1.4, -1.2, and -1.0. Overall, these r esults show that optical properties of a coccolithophore bloom are sen sitive to the coccolith:cell ratio and can vary between and within blo oms.