Coral fluorescence characteristics: Excitation - Emission spectra, fluorescence efficiencies, and contribution to apparent reflectance

The fluorescence characteristics of Caribbean corals have been investigated through in situ and laboratory spectral measurements. Four pigments (as defined by spectral characteristics) are the source of most of the observed emissions. In vivo excitation/emission spectra were measured to determine Stokes shift and bandwidth (FWHM) of each of the types. Fluorescence efficiencies for natural fluorescence of the chlorophyll in the zooxanthellae were estimated from IX in situ measurements, yielding values from 0.15 - 0.91%. Fluorescence efficiencies of the host pigments in 3 strongly fluorescent coral specimens were estimated from shipboard measurements and ranged from 4 - 6%. The quantitative data are being used in a computational model to investigate the contribution of fluorescence to apparent reflectance signatures.