Non‐toxic protection against epibiosis

Abstract

Epibiosis on four marine benthic invertebrate species was found to be reduced relative to other nearby surfaces, suggesting the existence of an underlying protection against fouling. In all four cases, toxic chemical antifouling defenses were wanting or inconsistent. However, the lack of epibionts could be attributed to the existence of non‐toxic protective properties in all instances, viz. periodic emergence and mutual grazing in the gastropod, Littorina littorea, cumulative filtration and an as yet unidentified fouling‐reducing property of the periostracum of the bivalve Mytilus edulis, repellency and, possibly, mucus secretion in the colonial ascidian, Cystodytes lobatus, burrowing, periodic emergence (intertidal individuals) and moulting in the crustacean, Carcinus maenas. It seems that such protective systems are often multiple, consisting of several, more or less overlapping, adaptations to reduce fouling. Characteristics of these non‐toxic, multiple protection systems and their significance for potential epibionts are discussed.