From December 1986 to November 1987 a biofouling panel test was carried out at Daya Bay, China (114°39'E; 22°40'N). A total of 83 species were encountered. The major dominants wereBugula neritina, Sinupetraliella umbonatoidea, Schizoporella unicornis, Hydroides elegans, Spirorbissp.,Ostrea radix, O. pestigris, Balanus reticulatus, B. amphitrite amphitrite, B. trigonusandB. cirratus. Bioattachment occurred over the whole year but it was distinctly seasonal. The most prolific period was May to October. The summer (Jun‐Aug) wet weight was 6·25 kgm−2but the second semiannual (Jun‐Nov) wet weight was the greatest, reaching 40–79 kg·M2.