Low electric current density enhances the calcification rate of the colonial Stony Coral Galaxea fascicularis

Abstract

This study assessed the effects of different electric current densities on the calcification and photosynthetic physiology of a massive, colonial stony coral species. Coral survivorship, calcification rate, and photosynthetic parameters (zooxanthellae density and chlorophyll fluorescence) were measured to determine the physiological and photosynthetic performance of Galaxea fascicularis after exposure to different electric current densities. After 60 days of treatment, survival of G. fascicularis was higher at low electric current density (10 mA m−2) than in the control and at high electric current density (100 mA m−2). Electric current did not alter zooxanthellae densities, but did enhance the photosynthetic processes (e.g. maximum electron transport rates (rETRm), and maximum quantum yield (Fv/Fm)) within 45 days. Coral calcification rate increased in response to low electric current density up to 30 days, but the effects of the electric current were not significant after a longer period of treatment. Overall, our results indicated that mineral accretion technology with appropriate electric current density conditions was somewhat helpful in enhancing coral growth, and thus this technique may be used in the restoration and management of massive stony coral reefs.