Effects of Thermal Stress on Fluorescence and Dinoflagellate Density in the Captive Coral, Anthelia spp.

Abstract

The obligate mutualistic relationship between corals and dinoflagellates is a classic example of symbiosis. Over the last few decades, coral reefs have been devastated by warm temperatures, hence, the necessity to develop a method to predict future mass bleaching events is higher than ever. Fluorescence might be used as an indicator of coral health, but very few studies have attempted to utilize it as a proxy for dinoflagellate density, which was the scope of the present research. The goal of this study was to determine the effects of thermal stress on fluorescence and dinoflagellate density in the captive coral, Anthelia spp.. Over a five-week period, tanks filled with Anthelia spp. underwent gradual increases in temperature, beginning at 28°C and ending at 33°C. Samples were quantified for fluorescence and dinoflagellate density using fluorescence microscopy and a maceration method. As temperature gradually increased, fluorescence values subsequently decreased. In contrast, dinoflagellate density first increased until it reached a threshold, followed by a sudden drop in numbers. Symbionts might be increasing their mitotic rate in response to thermal stress to compensate for the shortage of photosynthate supply for their host. Therefore, fluorescence analysis may be a potential predictor of coral bleaching in Anthelia spp..

Discipline: Biological Sciences

Faculty Mentor: Dr. Ross Shaw