A new flow-through bioassay for testing low-emission antifouling coatings

Current antifouling technologies are based on the continuous release of biocides into the water, and consequently discharge into the environment. Major efforts on more environmentally friendly coatings require efficient testing in laboratory assays, followed by field studies. Barnacles are important fouling organisms worldwide, largely increasing the hydrodynamic drag of ships and damaging coatings on underwater surfaces, and thus extensively used as a model in antifouling research, mostly in static, lab-based systems. Reliable flow-through test assays for the screening of biocide-containing antifouling paints, however, are rare. Herein, a flow-through bioassay was developed to screen for diverse low-release biocide paints, evaluating their effects on pre- and post-settlement traits in barnacles. The assay distinguishes between the effects from direct surface contact and bulk-water effects, crucial when developing low-emission antifouling coatings. In conclusion, this new flow-through bioassay adds a new tool for rapid lab-based first-stage screening of candidate compounds and novel antifouling formulations.