Single Ultraviolet-C light treatment of early stage marine biofouling delays subsequent community development.

Past studies of Ultraviolet-C (UV-C) radiation as a marine antifoulant have focused on repeated doses. However, single or very low frequency exposures of UV-C could create more plausible applications for certain marine structures. The objective of the study reported here was to apply a single treatment of UV-C radiation to an early stage marine biofouling community to observe subsequent effects on biofouling development. Biofouling formed over a 2-week field immersion received UV-C treatments of 0 (control), 4, 20, or 120 min, and subsequent progression was then monitored weekly for 16 weeks. Analysis of acute effects and later macrofouling development suggested direct toxicity of UV-C illumination to invertebrate recruits caused reduction of subsequent biofouling (compared to controls) that persisted for up to 16 weeks following the longest UV-C treatment. Thus, UV-C treatments spaced by days or even weeks could be an option for some applications of UV-C radiation as an antifoulant.