Abstract: A method of enhancing growth of aquatic organisms in an aqueous mineral-containing electrolyte such as sea water which comprises:(a) installing a cathode and an anode in the electrolyte,(b) applying a steady, pulsed or intermittent direct electric current across the cathode and the anode to effect electrolysis,(c) providing accreted mineral material on the cathode,(d) recruiting aquatic organisms on or in the vicinity of the cathode, and(e) creating by electrolysis conditions of higher alkalinity in the electrolyte in the vicinity of the cathode than in the electrolyte remote from the cathode to cause growth of the aquatic organisms in the conditions in the vicinity of the cathode, the placement of the anode being done in such a way as to minimize the effects of hydrochloric acid produced at the anode.The method is particularly described with reference to the growth of organisms which deposit calcareous substances, such as corals, for the creation of artificial reefs or coastal defence structures.