Phillips, C., Kaiser, K., Slania, V., Cristobal, A., Coelho, V. R.

Preliminary data on growth under different light and thermal conditions in branching coral species

2011

Twenty-fifth National Conference on Undergraduate Research (Abstracts), March 3 - April 2, 2011, Ithaca, New York

"Coral reefs are threatened due to thermal stress caused by global climate change. The higher temperatures lead to coral bleaching which results from the breakdown of the relationship between the coral and their symbiotic algae; this phenomenon is also heightened by conditions of increased light intensity. In this experiment we controlled light and temperature levels and analyzed growth patterns to see if shading could reduce stress on corals. The experimental design consisted of ten aquaria and three different coral species: Acropora muricata, Pocillopora damicornis, and Porites cylindrica, from American Samoa. Each tank had between ten and twelve corals of each species and different light levels: no shade, 50% shade, and 75% shade. We used 400W 10k metal-halide lights and adjusted the photoperiod per tank to have a total average photosynthetic active radiation of 22.6 moles m-2 day-1 (non-shaded). Temperature was regulated within the tank and recorded with loggers. Since the mean summertime maximum of American Samoa is 29.3 degrees Celsius, control tanks were kept either below the mean at 26 degrees Celsius, or close to the mean at 29 degrees Celsius. All other tanks were kept at 31 degrees Celsius to induce thermal stress. We took the buoyant weight of each coral at the beginning and end of the experiment to determine whether growth or tissue loss occurred. The statistical analysis did not yield a clear pattern, which we believe is due to the small sample size. However, our preliminary data show that P. cylindrica seems much more resistant to thermal stress than the other two species and also responds more positively to shading."

NOAA award NA09NMF4630105

NA09NMF4630105