In a previous report, we evaluated the biofouling properties of 15 various kinds of plastic and metal test plates by using a modified version of Miyajima's method. However, fouling values alone do not provide quantitative information on volume or weight of attached organisms. In this work we investigate the relationship between the fouling value and wet weight of fouling organisms on the plates. Six plates with different fouling properties were selected: PMMA, FRY, and SUS as highly fouling materials, and Silicone-Rubber, Cu-Ni9/1, and Cu as less fouling materials. These test plates were immersed in sea water for 405 days, from Dec. 19, 1993, to Jan. 25, 1995. Each month they were recovered and the Fouling Value (FV) was evaluated while also measuring the accumulated wet weight (W) of the attached organisms with a spring balance. FV and W showed a linear relationship on a logarithmic scale: LogW=1.886LogFV-1.830. Using this relationship, we can estimate the wet weight of marine sessile organisms attached to the surface of boat and ship hulls, and various kinds of marine structures, based on their FV.

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The occurrence of the solitary ascidian Molgula manhattensis (De Kay, 1843) in fouling communities of test plates immersed in the Golden Horn Inlet (Vladivostok port) and in the Rynda Inlet (Russky Is.) of Peter the Great Bay, Sea of Japan, was recorded in 1999. This species became dominant in the fouling community after 4 months of immersion of the test plates.

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Biofouling control of cooling water systems has been one of the severe problems for power plant operation. A lot of works have been carried out and many physical/chemical control methods are available. However, practical measures satisfied following criteria have not been developed: (1)reliable control for a long enough term, (2)broad availability, (3)low environment impacts, (4)simply operating, and (5)reasonable cost. Power plants have been coping with biofouling, using a combination of some measures applicable. Possible research targets of practical anti-biofouling are discussed from a user's view.

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This paper reviews biofouling control procedures in Japanese power station cooling water systems. Antifouling paints and chlorination are widely used to prevent biofouling. Silicone-based coatings and self-polishing paints containing Cu₂O are used commonly as antifouling coatings. Silicone-based paints are very effective under high water velocity. There are several kinds of cleaning and inspection robots to remove fouling organisms in intake culverts. Antifouling methods for condensers comprise online sponge ball cleaning, back wash, and self-cleaning debris filters. Electro-conductive paint and electrochemical methods are used in limited areas in cooling water systems. A robot has been developed for cleaning and inspection of condenser tubes.

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