The characteristics of the soup stock made from seaweed and dried bonito prepared with drinkable deep seawater (DSW water) were compared with those prepared with tap water (Tap water) and natural mineral water (NM water). As a result, there was remarkable difference of the taste among the three kinds of soup stocks although there were little differences of the pH value and turbidity. As a reason why the taste of the soup stock prepared with DSW was the best one in this study, it was suggested that the characteristics of the tastes of the soup stocks were determined by the concentrations of sodium (Na) and potassium (K) included in the water. Furthermore, the soup stock made from seaweed and dried bonito prepared with DSW water accelerated the expression of tight junction (TJ) -related protein “Occludin (OCLN)” using an intestinal epithelial model by Caco-2 cells. However, the soup stock prepared with Tap water showed much weaker effect on the expression of OCLN. Because the soup stock made from dried bonito only showed the most remarkable accelerating effect on the expression of OCLN, it was suggested that the accelerating effect of the soup stock made from seaweed and dried bonito prepared with DSW water on the expression of OCLN was caused by substances in the soup stock made from dried bonito only prepared with DSW water. From these results, it was elucidated that the soup stock made from seaweed and dried bonito prepared with DSW showed not only good taste but also accelerating effect on the expression of TJ-related protein.

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Rhyzostome jellyfish, Mastigias papua, contain symbiotic dinoflagellates known as zooxanthellae in cells of mesoglea. It is well known that endosymbiotic zooxanthellae are capable of CO2 uptake and fixation and subsequent carbon translocation to jellyfish tissues. To evaluate the effect of deep seawater (DSW) on the growth rates of M. papua medusae, they were reared at 20‒25℃ for 50 days in 3 different waters: DSW, surface coastal seawater from Akazawa Port, Ito, Shizuoka (SCSW), and mixture of equal volume of DWS and SCSW. Survivorship was 100％ for all individuals used in the experiments. The specific growth rate of M. papua reared in the DSW was significantly higher than that observed in the SCSW, suggesting that high-nutrient-containing DSW is effective in carbon fixation of endosymbiotic zooxanthellae, which subsequently enhances the growth rate of host medusae. The density of zooxanthellae in the mesoglea did not show any significant differences among medusa groups reared in the three different seawater types. Hence, it is highly recommended to use the DSW for culturing jellyfish species with symbiotic zooxanthellae, such as upside-down jellyfish Cassiopea spp.

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