The synergistic effects of hydrogen peroxide and elevated seawater temperature on the metabolic activity of the coral Galaxea fascicularis

Abstract

We examined quantitative changes in the metabolism of the coral Galaxea fascicularis caused by increases in both hydrogen peroxide (H2O2) concentration and seawater temperature. Seawater temperatures were maintained at 27 or 31°C in a well-controlled incubation chamber, and three levels of H2O2 concentration (0, 0.3, 3.0 μM) were used in experimental treatments. Gross primary production, calcification rates and respiration rates were all affected by increased H2O2 concentrations and high seawater temperatures. Individual treatments of high H2O2 or elevated seawater temperature alone caused significant declines in coral photosynthesis and calcification rates within the 3-day incubation period. The synergistic effect of high H2O2 combined with high seawater temperature resulted in a 134% increase in respiration rates, which surpassed the effect of either H2O2 or high seawater temperature alone. Our results suggest that both high H2O2 concentrations and elevated temperatures in seawater can strongly affect coral metabolism; however, these effects cannot be estimated by simply summing the effects of individual stress parameters.