Enhancing settlement and growth of corals using feeble electrochemical method

Abstract

Considerable interest has been generated by the potential application of electric-fields to promote settlement of coral larvae and enhance growth rates of coral juveniles. Also, it has been reported that when an electric current is run through an attached iron base, coating by the resultant accretion of minerals through electrochemical processes, promotes the growth and survival of transplanted coral fragments. However, further investigations are required due to currently very limited scientific evidence. In the present study, the optimal range of electric current density for coral growth was investigated through field observations in Okinawa. It was found that naturally settled reef-building corals on the surface of a floating pontoon, on which an electrical treatment was applied to prevent corrosion, grew faster in the areas where the actual electric current density was greater than 10mA/m super(2). An in situ experiment was, then, carried out on coral fragments that were attached to four iron-framed structures installed on the seabed with different feeble current densities. As a result, the coral fragments with the current density of 20 similar to 100mA/m super(2) showed relatively, but not always, faster growth than others. It was suggested that adverse effects might occur under strong electric currents. On the other hand, larvae exhibited far greater settlement affinity for the mineral accreted substrates without electric current than for the unglazed ceramic plates.