Changes in fluorescence in captive soft corals, Anthelia spp. & Nephthea spp., after exposure to thermal stress

Abstract

Climate change is increasing global ocean temperatures causing a decline in coral reefs, mainly by the process of bleaching, involving the expulsion of zooxanthellae. The health of the soft corals Anthelia spp. and Nephthea spp. were assessed by the degree of fluorescence they produced. It was predicted that a decrease in coral health from thermal induced stress would also decrease fluorescence. Coral fragments underwent the following treatments: 30ºC, 31ºC, 32ºC, 33ºC, 34ºC and no treatment (26-28ºC). Treatments were carried out for 24 hours. The fragments were subjected to 400nm UV light from an Olympus X-Cite 120Q EXFO light source. Photos of the coral were taken using an Olympus XM10 camera mounted on a dissecting scope that produced a live feed to the program cellSens Standard. The images were analyzed using ImageJ software to determine the mean corrected fluorescence per treatment. The data were analyzed with a one-way ANOVA. Anthelia showed a significant difference in the degree of fluorescence between the control treatment (26-28ºC) and the 33ºC treatment, while Nephthea did not show a significant difference. This knowledge may be useful in surveying large areas of coral reefs via fluorescence imagery.

Discipline: Biology

Faculty Mentor: Dr. Ross Shaw