Proposal of an absorption method to discriminate phytoplankton optical groups in natural mixed assemblages of the Mediterranean Sea

Natural phytoplankton assemblages generally show high diversity in pigment composition, affecting their absorption responses. We propose an absorption method to discriminate, in natural mixed assemblages, the spectral signatures of seven phytoplankton groups with different marker pigments composition. Proposed routine is based on a pair-wise similarity computation, by means of Spectral Angle Mapper algorithm, between each natural spectrum and reference spectra of phytoplankton groups. Regressions between similarity indices and marker pigments concentrations show significant correlation coefficients, highlighting the power of this method and the possibility to optically determinate phytoplankton composition in mixed assemblages. The method represents an useful tool for the optical discrimination of phytoplankton groups.