By Brandi Wallace under the advisement of  Jack Hardy
Western Washington University, Shannon Point Marine Center, SEARUN Program

INTRODUCTION
Coral bleaching is a widespread global phenomenon in warm tropical waters between 20 degrees N and S latitude.  Bleaching is a loss of zooxanthellae from the animal and/or a reduction of photosynthetic pigment concentrations in resident zooxanthellae (Glynn, 1992). A significant factor contributing to massive bleaching is the elevation of ambient sea water temperature beyond normal seasonal values (Hayes and Goreau 1991).

A method to accurately determine the degree and spatial extent of coral bleaching is needed.  My study examined the relationship between spectral signatures and pigment concentrations in cultured anemones. The relation between spectra and pigmentation should be useful for future monitoring of reef health by remote sensing platforms including boats, aircraft, and satellites (Myers et al. 1997).

METHODS
The anemone Aiptasia pallida was exposed to increased temperature and ultra-violet radiation (see  poster by D. Bostrom). I used a Benthic Spectrofluorometer (BSF), specifically designed to collect wavelength-specific measurements of reflectance and fluorescence (Figures 1&2). Fluorescence was measured in response to an excitation light source focused through a 440 ±10nm narrow-band filter. The probe was held <10mm from the oral disk of the anemone, in a darkened room with no ambient light. Reflectance measurements were taken outdoors under solar light and are a relative value compared to a white reflective surface. The data represent the mean of measurements on 3 to 6 anemones.

RESULTS

DISCUSSION
The fluorescence and reflectance results indicate bleaching occurred in response to enhanced temperature and UV-B radiation.  The density data show the anemones did lose protein with UV treatment, and the % expulsion illustrate an increase in expulsion with UV treatment (see poster by J. Berger and T. Markus).  Pigment within the anemone decreased in the recovery  experiment.  The amount of pigment (pg/cell) found within the  recovery anemones was less than that found in the expelled zooxanthellae (see poster by E. Macri and S McKagan). These results are supported by my measurements of the decreased  fluorescence and increased reflectance for the anemones exposed to higher dosages of UV-B irradiation and temperature effects.

ACKNOWLEDGMENTS
The author would like to thank the National Science Foundation (grant DBI-9711075) for funding,  PIs Gisele Muller-Parker, Suzanne Strom, and Jack Hardy, the staff at Shannon Point Marine Center, Gabrielle Mowlds, Kelley Bright, Clay Cook for supplying us with anemones and Charles Mazel for providing us with the Benthic Spectrofluorometer.

REFERENCES
Glynn PW. 1992. Coral reef bleaching ecological perspectives. Coral Reefs 12: 1-17.

Hayes, R.L. and T.J. Goreau. 1991. The tropical coral reef ecosystem as a harbinger of global warming. World Resource Review.

Myers M., J.T. Hardy, C.H. Mazel, and P. Dustan. 1998. Optical spectra and pigmentation of Caribbean reef corals and macro algae. In press. Coral Reefs.