Fuki(Japanese butterbur), Petasites japonicus, is a wild vegetable widely used as a cooking material because of its unique taste and toughness. As the plant is seasonally harvested and rarely cultured, materials are often boiled for preservation and preparation for further cooking. However, the materials should be treated in 0.4% calcium lactate solution(CLS, a foodindustrial cooking solution permitted for edible wild plants)to avoid losing toughness during boiling. In the present study, the author examined the possibility of substituting deep seawater(DSW)and electro-dialyzed deep seawater (EDDSW) for CLS. The plants boiled in DSW, EDDSW or CLS left more toughness than those boiled in Fuki well(conventional)fresh water. The cutting force of EDDSW-treated plants was equivalent to CLS-treated plants. The EDDSW effect was quite definite(p=0.14%)and stable, whereas the effect of DSW was hardly defined and unstable. In preliminary sensory evaluations, Fuki cooked with EDDSW showed good toughness. The contents of calcium, magnesium and hexametaphosphatesoluble pectin in Fuki cooked with DSW and EDDSW were more than those in conventional water. These results suggested that divalent cations, such as Mg²⁺ and Ca²⁺, likely interact with pectin to form insoluble pectic substances. As with other results of cooking in various kinds of ion solutions, we assumed that calcium ions play a main role in the firming of boiled Fuki, and EDDSW might be a usable substitute for calcium lactate.

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On the Tsushima Island, a practical application of an ocean thermal energy conversion (OTEC) and desalination plant is expected due to the short of electric power and drinking water. In the present study, we made oceanographic observation in the area northwest of Tsushima Island on August, October and November in 2005 and July, August and October in 2006 to obtain physical and chemical data (water temperature, salinity, dissolved oxygen, nutrients and velocity of currents) and topographic data, which is necessary for designing the hybrid OTEC system.
Approximate temperatures in the surface and deep seawaters (SSW and DSW, respectively) at about 170 m in depth were 28°C and 5 °C in August 2005, and 21°C and 8 °C in November. From the thermal data, OTEC was supposed to be active from August to October. The salinity in SSW and DSW were 31.0-31.8 31.8 PSU and below 34.2 PSU, respectively in August 2005; between depths of 30 and 50 m a drastic halocline was detected. The low salinity of SSW in summer suggests the influence of continental river waters. Dissolved oxygen in SSW and DSW in August 2005 were comparatively high (> 5.0 ml/1). Water quality showed drastic seasonal changes in SSW shallower than a depth of ca. 150 m, which may be the influence of continental river waters. On the contrary, DSW characterized by high salinity and low temperature was thought to be the cold water endemic to Sea of Japan. On an expected cold water pipe (CWP) (180-200 m in length, 1.7 m in diameter) designed for a seabased 1, 000 kW OTEC plant, the maximum bending moment was estimated to be larger than 3, 922 Nm. In the case of employing a land based OTEC plant at Cape Sao on the north of Tsushima Island, length of the CWP should be longer than ca. 9.5 km.

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During a high water temperature period in summer, abalones decrease consumption of food and hardly grow in temperate waters in Japan. In this study, growth and survival rates of abalone were compared between a culture in running surface seawater (SSW) and another culture in running SSW cooled by mixing Suruga Bay deep seawater pumped from a depth of 397 m (SSW + DSW) at Shizuoka Prefectural Research Institute of Fishery from August to December in 2004 or 2005. Approximately 500 shells of Haliotis gigantea (43 mm in shell length) and an F 1-hybrid abalone (male H. discus hannai × female H. gigantea; 41 mm in shell length) were cultured in net cages (100 × 100 × 35 cm) set in tanks (5t volume) by feeding enough artificial compounds. In H. gigantea, survival rates in SSW (23.9 ± 2.2°C) and SSW + DSW (19.3 ± 1.1°C) were 94.6 and 96.8% and daily growth rates (50 samples) were 27 and 62 μm d^-1, respectively. In the hybrid, survival rates in SSW (22.4 ± 1.0°C) and SSW+DSW (19.6 ± 0.8°C) were 99.5 and 99.8%, and daily growth rates (50 samples) were 44 and 60 μm d^-1, respectively. Therefore, SSW + DSW surely improved growth and survival of abalone in summer and may allow us to shorten its total culture period.

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The attached diatom flora in the aquaculture facility, Kochi Prefectural Deep Seawater Laboratory, Muroto, Japan, in which Pacific deep seawaters (DSW) were pipelined from depths of 320 m and 341 m, was studied using light microscopy. A total of 37 species in 21 genera were recorded from the tanks (10-16°C). The popular identified species were Navicula agnita, Craspedostauros decipiens, Nitzschia laevis, Gomphoseptatum aestuarii, Diploneis papula, Tabularia fasciculata and T. investiens; among them, C. decipiens, G. aestuarii and D. papula recorded the highest relative frequency rank (> 50%) in at least one sample. Some diatom species were previously reported from aquaculture facilities in Toyama prefecture, Sea of Japan coast, in which colder (< 10°C) DSW is used. Among six examined tanks, one tightly covered outdoor tank was prepared for the present study by running DSW for forty days before sampling. Two samples collected from a wall and detached colonies floating in the tank, included only 4 species, showing the cleanliness of DSW. Other samples were collected from five tanks of a variety of size, period and cultured organisms. Five samples collected from a wall or other substrata in three abalone (two outdoor and one indoor) tanks included 12 to 24 species; the richest flora (24 species) was recorded from a net cage in the indoor tank in which surface seawater (SSW) was also mixed for adjusting water temperature. The other two samples, collected from one outdoor kelp tank and one indoor shrimp tank (with some seaweed), included 8 and 4 species, respectively. We concluded that the inclusion of organisms, particularly abalone, as well as mixing of SSW increase the species richness of attached diatoms in DSW and that diatom species occurring in high frequency are adequate for high production in culture in DSW.

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