Biodegradable surfactants do not improve antifouling or fouling-release performance of polydimethylsiloxane

Surfaces that combine low-toxicity antifouling effects with fouling-release properties are an intriguing possibility for developing effective measures against marine biofouling. This study field tested siloxane-based fouling-release surfaces enhanced by adding biodegradable surfactants. Two different surfactants were added to a standard polydimethylsiloxane (PDMS) surface, as well as to PDMS soaked in silicone oil, and compared to controls without surfactant augmentation. Antifouling and fouling-release performance was assessed over 11 to 13 weeks against the most prominent fouling species at three locations in Cape Breton, Nova Scotia, Canada. Using nonlinear mixed effect analysis, surfactants were found to have little impact on the progression of biofouling on PDMS without silicone oil in all three sites and had no additional impact on the progression of biofouling on PDMS augmented with silicone oil. (Silicone oil was found to delay biofouling in PDMS without other additives.) Given the known toxicity of some surfactants to invertebrate larvae, future efforts should consider either higher concentrations or alternative varieties for incorporation into fouling-release surfaces.