Artificial Reef

Mineral accretion involves applying a low voltage current to a metallic structure to cause limestone to crystallize on the surface, to which coral planulae can attach and grow. The electric current also speeds post-attachment coral growth.
EMA works like charging a battery with a positive pole, the cathode, and a negative pole, the anode. Applying electric current attracts various dissolved minerals to either the cathode or the anode. Chemical reactions then take place at both poles. On the anode, bubbles of oxygen and chlorine gas form. These bubbles float to the surface and dissolve into the air. On the cathode, bubbles of hydrogen gas and a limestone precipitate appear.
The voltage is low enough that it can be generated by floating solar panels or from wave motion.
A coalition of scientists named the Global Coral Reef Alliance (GCRA) is developing a technique called the Biorock Process using mineral accretion for reef restoration, mariculture, and shoreline protection.