SPECTRAL MEASUREMENTS OF FLUORESCENCE EMISSION IN CARIBBEAN CNIDARIANS

Fluorescence effects in cnidarian host tissues have been investigated only sporadically and have largely been described qualitatively. In pa st studies specimens were selected for investigation based on their ap parent fluorescence under either daylight or ultraviolet (W-A or UV-B) illumination, thereby missing relationships between the 2 effects. In this study samples of a Variety of Caribbean cnidarian species were s elected based on their in situ responses to daylight and/or UV-A illum ination. Fluorescence emission spectra (excitation wavelength 365 or 4 05 nm) were measured for sources in the host tissues. A sorting of spe cimens by similarity in spectral shape resulted in groupings containin g members of different species. Emission spectra measured from separat e specimens of a single species exhibited clear differences in some ca ses. There was no correlation between the spectral shape and the relat ive fluorescence intensity observed under illumination by ultraviolet light (UV-A, emission maximum approximate to 360 nm). Emission maxima fell in the range of 480 to 590 nm. The only source of fluorescence at wavelengths greater than 650 nm was chlorophyll in zooxanthellae. Som e specimens contained material with an emission spectrum identical to that of phycoerythrin (peak wavelength approximate to 575 nm). The res ults are of interest for studies of photoecology and for applications of coral reef optical remote sensing.