抄録
Seaborne efficiency is influenced by biofouling on a ship's hull. Barnacles are one of the major hull-fouling organisms. We took a total of 69 samples during sailing, anchoring, and berthing from 2013 to 2016, quantified the species of barnacles by qPCR, and counted individual nauplius and cypris larvae. The most species— such as Chthamalus challengeri, Tetraclita japonica, Balanus trigonus, Amphibalanus amphitrite, A. eburneus/A. improvisus, Fistulobalanus albicostatus, Megabalanus rosa, and M. coccopoma—were detected from two samples taken in Kagoshima Port in 2014. However, the numbers of cypris larvae were limited drastically to less than 22 individuals （m-3） regardless of the sampling sites, while those of nauplius larvae varied up to 9,828 individuals （m-3）. Approximately 2 individuals each settled onto both sides of a flat plate （30 centimeters square） immersed at berthing in Onomichi Port （n=6）. We estimated that approximately 11,500 individuals settled onto the underwater hull surface （518 m2） during berthing. In Osaka Bay, Megabalanus species existed constitutively. The height of such large adult barnacles influences frictional drag. It is important for the prevention of biofouling to reduce the frequency of the interaction of cypris larvae with the hull so as not to decelerate the speed to less than 0.6 m s-1 until arrival at the next port.
