In the study of antifouling, it is important to establish a method for culturing barnacle larvae for settlement assays. In the laboratory, the diatom Chaetoceros gracilis has been shown to be one of the best diets for raising the larvae of Balanus amphitrite. We applied this culture method to B. trigonus, supplying the larvae with C. gracilis at concentrations of 1, 3, 5, and 7×10⁵cells/ml at 25°C. Larval growth in terms of rate of development to the cyprid stage, and the survival rates at different food concentrations, indicated that the optimal food concentration for B. trigonus was 5×10⁵cells/ml. At this concentration, the larval survival rate on the sixth day following the start of culture was 84%, and about 71% of the larvae had developed to cyprids by then. Parallel observations on larvae of B. amphitrite showed that at its optimal food concentration of 3×10⁵cells/ml, it took one day less to develop to the cyprid stage than did B. trigonus. In settlement assays using cyprids of each species and six-well multiwell plates, the percentage of settlement in response to a crude extract of adults of their own species for B. trigonus was 39±13%, whereas settlement on plates without the extract was 9±2%; the corresponding values were 44±12% and 20±10% for B. amphitrite. These results suggest that the larval culture and settlement assay methods established for B. amphitrite can also be applied to B. trigonus.

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The phylogeny of the six species of the Balanus amphitrite complex found in Japan was analyzed based on nucleotide sequences of the mitochondrial COI (cytochrome oxidase subunit I) gene and the morphology of the barnacles. The six species are B. amphitrite Darwin, B. eburneus Gould, B. improvisus Darwin, B. albicostatus Pilsbry, B. kondakovi Tarasov and Zevina, and B. reticulatus Utinomi. Judging from the high bootstrap values in the sequence-based phylogeny, these six species appear to comprise a monophyletic group divided into two clusters of three species each: B. amphitrite, B. eburneus, and B. improvisus; and B. albicostatus, B. kondakovi, and B. reticulatus. The cladogram based on morphology is congruent with the sequence-based one; the first species cluster is characterized by a multidenticulate labrum, the second by a simple labrum.

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A new species of coral-inhabiting barnacle, Trevathana paulayi, is described from Guam, the southernmost of the Mariana Islands. This new species is distinguished from Trevathana dentata (Darwin), formerly called Savignium dentatum, by the color of the wall, the lack of an occludent ledge on the scutum, and the shape of the tergum. The definition of the genus Trevathana is emended to accommodate this new species and also to include Savignium orientale Ren.

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A new mangrove barnacle, Balanus thailandicus sp. nov., is described from the Puyu Canal, Tamalung Bay, Satun, southwest Thailand. The new species has the common characteristics of the Balanus amphitrite complex and is more or less sympatric with B. reticulatus, B. amphitrite, B. patelliformis, and B. variegatus. Balanus thailandicus is most similar to B. reticulatus, but it is clearly distinguishable from the last three mentioned species of the complex in having the parietes folded or ribbed in adults but smooth in juveniles, parietal tubes solid in the upper half and interrupted by transverse septa in the lower part, the large number of articles in the anterior ramus of cirrus I, and erect hooks below the posterodistal angles of the articles of cirri III and IV.

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Anti-fouling properties of various materials including commonly used plastics and metals were evaluated monthly for one year by a Miyajima's method based on the standardization of fouling grade at a moorage in Mikawa Bay, Aichi Prefecture. Plastics (PVC, PET, FRP, and PTFE) were superior in their anti-fouling properties to metals (Ti, SUS, Al, Fe, Zn, and Ni) for the first seven months (November to May) when macro- fouling organisms were few; however, except Silicone rubber, copper, and its alloys, the differences diminished due to the heavy settlement of sessile animals starting in June, and the total fouling value became almost the same in October. Silicone rubber showed the similar fouling values for the first eight months as the other plastics, but it showed lower values in August due to the falling off of sessile animals from its surface. Copper and its alloys had the most superior anti-fouling properties among the test materials, although their effectiveness was less as the proportion of copper in the alloy decreased. The anti-fouling property of test materials can be ranked as follows, in decreasing order of effectiveness, based on the highest observed fouling value for each: Cu>>Cu/Ni(90/10)>>Cu/Ni(70/30)>Cu/Zn>Si-R>>SUS≥Zn, Ni, PET≥PVC, FRP, PTFE>Fe, Al, Ti.

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