The effects of hydrogen peroxide on metabolism in the coral Goniastrea aspera

Abstract

Coral metabolism reflects the physiological condition of a coral colony. We studied coral metabolism using a continuous-flow, complete mixing (CFCM) experimental system. Small-size Goniastrea aspera coral colonies were incubated in the CFCM system with and without hydrogen peroxide (H 2O 2) added to the supplied seawater (0 µM H 2O 2 for 12 days; 0, 0.3, 3.0, and 30 µM H 2O 2 for 3 days, for each treatment) Without addition of H 2O 2, coral metabolism, including photosynthesis (gross primary productivity) and calcification, was relatively stable and there were no significant metabolic changes, suggesting that, without H 2O 2 added to the CFCM system, the corals did not suffer significant stress from the experimental system over a 12-day incubation period. When H 2O 2 was added, large decreases in photosynthesis and calcification were observed. The non-parametric Mann–Whitney U-test showed that there were statistically significant differences in photosynthesis after addition of 3.0 µM and 30 µM H 2O 2, compared with the control. We also found statistically significant differences in net calcification after addition of 30 µM H 2O 2. Thus, the incubation experiments suggest that higher H 2O 2 concentrations in seawater clearly influence coral metabolism. However, the results also suggest that the current seawater H 2O 2 level in Okinawa is not likely to pose significant acute effects on the metabolic activities of corals.