The International Organization for Standardization (ISO) has published ISO 21716-4:2025 a new standard defining a bioassay method for screening antifouling paints using algae under controlled laboratory conditions.
Development of the standard was led by Dr Ryuji Kojima, Principal Researcher at Japan’s National Maritime Research Institute (NMRI), who acted as project leader within ISO Technical Committee 8, Sub-Committee 2 on Marine Environment Protection.
The new standard introduces a test method for evaluating the growth-inhibiting effect of antifouling paints using brown algae (Ectocarpus sp.), completing the four-part ISO 21716 series. Earlier parts of the series addressed general requirements, barnacles, and mussels.
Biofouling on ships’ hulls can reduce vessel efficiency, increase fuel use and emissions, and contribute to the transfer of invasive species. Standardised laboratory methods for evaluating antifouling paint performance should help to deliver consistent, scientifically validated results of their ability to prevent this from happening.
