Unmixing coral fluorescence emission spectra and predicting new spectra under different excitation conditions

An algorithm was developed that uses prototype spectra and least-squares mi nimization to unmix the relative contributions of individual pigments to th e composite fluorescence emission spectrum of reef corals. Field measuremen ts indicated that it was necessary to include allowance for spectral shift of the wavelength peak of the prototype emission spectra. The unmixed spect ra are used to predict the shape and amplitude of composite spectra that wo uld be expected under different excitation conditions. We found that, for c ases in which the pigments occur singly or with significant spectral separa tion, it is necessary to consider the properties of the excitation light so urces, only, to make accurate predictions. In cases with spectral overlap t he contribution of interpigment coupling cannot be neglected. (C) 1999 Opti cal Society of America.