As a course of multiple/cascade utilization of deep-sea water (DSW, known as a cold, clean and nutrient-rich seawater) pumped from Toyama Bay, a self-sustainable abalone culture system was proposed. In the system, DSW enhances the intercalary growth of kelp after cutting off its blade tip, which is fed to abalone cultured in the warmed drainage of kelp culture. In the present study, Laminaria japonica Areschoug (ca. 50 cm in total length) was reared in outdoor tanks using running intact (3 °C) or warmed DSW (11 °C). Blade tips were cut off at 15 cm above the stipe-blade transition every month to feed the juvenile abalone Nordotis discus hannai (Ino). Growth was examined using a hole punching method from March 2001 to January 2002. All of the pruned kelp continued to grow even after the repeated cut-off by 11 times. The mean elongation varied from 1.3 to 8 cm/week in length, recording the maximum of 16.7 cm/week in March. The cut-off blade tips formed sori in 2 weeks every month when cultured using DSW (11 °C). Juvenile abalones (41mm in shell length) were fed 0.25 g and 0.75 g of blade tip per shell in a day at 15 °C and 18°C, respectively. The pruning method allows us to use shorter culture tanks, to keep high kelp densities without forming canopies, to prevent elongated kelp from deteriorating by exposure to the air, and to utilize all of the produced materials of kelp without wasting. In addition, the sorus formation provides year-round kelp seed production. In the proposed system, a quarter of cultured kelp is rotationally pruned every week to supply sufficient blade tips to abalone. Using the system, 12, 000 to 16, 000 abalones (40 mm in shell length) can be reared by culturing 12, 000 pruned kelps.

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Muroto deep seawater is cold, pristine and rich in nutrients. Even though the deep seawater of this area is used for various industrial purposes, no comprehensive study on the levels of environmental pollutants is available at present. So, a study was undertaken on the pollutants in the seawater off Muroto and Kochi Port. All the pollutants analyzed - PCBs, HCB, CHLs, BTs, brominated and phenolic compounds existed at very low levels in all the samples analyzed, and below detection limits, in many instances.

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Hyaluronidase inhibitory effect was found in the water extract of a diatom species, Navicula directa (W. Smith) Ralfs (N. directa) isolated from deep sea water (DSW) of Toyama Bay. Hyaluronidase inhibitory effect (IC₅₀: 28 μg/ml) of ethanol insoluble fraction from the water extract was 4 times stronger than that (IC₅₀: 110 μg/ml) of a current anti-allergic agent, disodium cromoglycate (DSCG). Ethanol insoluble fraction was very thermostable and showed a wide range of pH stability. On the basis of these data, ethanol insoluble fraction seemed to be useful for the treatment of allergic diseases, such as atopic dermatitis and pollinosis.

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Water mass and water properties (such as nutrients, particulate matter and organic matter) at the intake sea area of Suruga Bay deep seawater off Yaizu were investigated in November 1999. Water temperature at the depths of 350 m and 700 m were 10 °C and 5 °C, respectively. Salinity showed a maximum at the depth of 150 m and a minimum at the depth of 500 m. The seawater at both intake depths were classified into a subpolar intermediate depth water by these characteristics of temperature and salinity. The concentrations of nutrients increased with depth, and at 400 m and 700 m depths the concentrations were 26.1, μM nitrate, 1.9 μM phosphate, 58.3 μM silicate and 35.6, μM nitrate, 2.6, μM phosphate, 103 μM silicate, respectively. This indicates that the deep seawater was rich in nutrients. Although the concentration of suspended matter of deep seawater was higher than that of surface seawater probably due to resuspended bottom sediments, number of bacteria, and concentrations of dissolved and particulate organic carbon of deep seawater were significantly lower than those of surface seawater.

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In order to evaluate a behavior and fertilization effects of pumped-up deep seawater into an euphotic zone, free-drifting buoy experiments on tracking a naturally-occurring upwelling and an artificially pumped-up deep seawater were reviewed. Preliminary experiments of an autonomous profiling vehicle having CTD/Chl sensors was also conducted at a shallow coastal sea.

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Within 3 major characteristics of low temperature, rich nutrients and cleanliness of deep ocean water, cleanliness is reviewed based upon information reported in the world in the following 7 aspects; 1) biological, 2) contamination of pathogenic and polluted organisms, 3) chemical pollutants, 4) suspended matter, 5) organic matter, 6) heavy metals, and 7) radioactive materials. Possible advantages of resource utilization of deep ocean water supported by each aspect of cleanliness are described, and probable changes of cleanliness during various storages of deep ocean water are also mentioned.

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