Characterization of physiological states of the suspended marine microalgae using polarized light scattering

Physiological states of marine microalgal cells can influence photosynthesis efficiency, which affects approximately half of global carbon fixation. The detection of the algae physiological profiles is important for marine ecology and economy. In this paper, we propose a polarized light-scattering method to detect sensitive changes in the physiological states of the suspended marine microalgal cells. Our experimental setup is designed to measure the scattered polarization parameters of the cells suspended individually in the seawater. Two species of microalgal cells cultured in the laboratory were measured for several days. Experimental results showed that both species display distinctive changes in their polarized photon scattering features corresponding to changes in their physiological states. The changes are far more prominent than those displayed in unpolarized light scattering. Microscopy observations, simulations for microspheres of different diameters and refractive indices, or different shapes, indicated that the polarization features of the scattered photons are sensitive to the submicrometer microstructures of the cells. This study demonstrates the potential of the polarized light-scattering technique to characterize the physiological states of suspended marine microalgae.