Settlement and growth of copper-tolerantEctocarpus siliculosus (Dillw.) Lyngbye on different copper-based antifouling surfaces under laboratory conditions

The first paper of this series reports the development of an algal culture system suitable for monitoring marine antifouling characteristics of copper-based alloy materials under standardized laboratory conditions, using the marine-fouling algaEctocarpus siliculosus. The physical and chemical conditions necessary for both the formation of corrosion films typical of those formed at sea and vigorous growth of the alga in the incubating medium were investigated using copper-nickel 90/10 as a test material. Preincubation of sample plates in seawater for up to 140 days proved necessary in order to generate passive corrosion films which continued to release copper at sufficiently low rates to permit algal growth, spore production and settlement. Seawater sterilization and addition of supplementary algal nutrients did not significantly affect the equilibrium rates of copper loss or the composition of the corrosion films. Aeration of the medium accelerated the attainment of this equilibrium but the addition of Fe2+ ions had no effect. Surface preparation and orientation of sample plates had little effect on rates of copper loss. Corrosion rates recorded in these trials compare favourably with those reported for similar materials exposed at sea.