Inter-Research
Marine Ecology Progress Series

ABSTRACT: Fluorescence effects in cnidarian host tissues have been investigated only sporadically and have largely been described qualitatively. In past studies specimens were selected for investigation based on their apparent fluorescence under either daylight or ultraviolet (UV-A or UV-B) illumination, thereby missing relationships between the 2 effects. In this study samples of a variety of Caribbean cnidarian species were selected based on their in situ responses to daylight and/or UV-A illumination. Fluorescence emission spectra (excitation wavelength 365 or 405 nm) were measured for sources in the host tissues. A sorting of specimens by similarity in spectral shape resulted in groupings containing members of different species. Emission spectra measured from separate specimens of a single species exhibited clear differences in some cases. There was no correlation between the spectral shape and the relative fluorescence intensity observed under illumination by ultraviolet light (UV-A, emission maximum = ca 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. Some specimens contained material with an emission spectrum identical to that of phycoerythrin (peak wavelength = ca 575 nm). The results are of interest for studies of photoecology and for applications of coral reef optical remote sensing.

KEY WORDS: Cnidarians . Fluorescence . Photoecology . Remote sensing

Published in MEPS Vol. 120 (1995) on April 20
Print ISSN: 0171-8630; Online ISSN: 1616-1599. Copyright © Inter-Research, Oldendorf/Luhe, 1995