THE INTERRELATION OF CATHODIC PROTECTION AND MARINE MACROFOULING

This paper presents and discusses the results of laboratory and field experiments on the interrelation of cathodic protection (CP) and marine macrofouling. Tests in the sea revealed that fouling settlements were greatly enhanced by CP. Calcareous shell-dwelling organisms such as barnacles and oysters, and a calcareous alga, Jania rubens, were particularly prolific on cathodically protected substrata. Laboratory studies with the oyster, Crassostrea madrasensis (L.), indicated that interfacial alkalinity generated by CP might enhance shell growth in the organism. The oyster reached a larger size on cathodically protected substrata than on the controls. Tests done in the presence and absence of fouling under natural conditions showed that fouling can bring about rapid decay of potential during interruption of the protective current, causing early corrosion. The implications of the findings to the performance of fixed marine and offshore structures are discussed.