Phytoplankton Functional Type (PFT) Ocean Color Inversion: Building A Model For Noctiluca Miliaris Detection In The Arabian Sea Based Upon Species-Specific Inherent Optical Properties (IOPS)

Noctiluca miliaris is a large phagotrophic dinoflagellate with obligate photosynthetic symbionts, Pedinomonas noctilucae, a green-pigmented pransinophyte. Although details about symbiont regulation, triggers for phagotrophy, and bottom up controls are sparse, recent attention on N. miliaris has grown due to its apparent emergence as a bloom-forming species in the Arabian Sea since the mid-1990s. Although large and easily visible by eye, most reported occurrences have been verified by microscopy, which limits the ability to discern highly resolved temporal and spatial patterns. Field investigations of the inherent optical properties associated with N. miliaris blooms yield spectral absorption coefficients distinct from nearby communities dominated by either diatoms or dinoflagellates. Backscattering spectra are consistent with those for large particles (spectrally flat) with strong spectral features associated with absorption peaks; backscattering ratios are weak, also consistent with expectations for large, strongly absorbing cells. Semi-analytic inversion of ocean color reflectance spectra (both non-linear and linear matrix inversion approaches) indicate that the presence of N. miliaris can be detected, but the concentration cannot be quantified. These results are consistent with those suggested by published Hydrolight simulations.