Abstract
The effect of the Muroto deep seawater on the growth of the red alga, Gracilaria chorda (Holmes), was stu died.The Muroto surface seawater and the Yashima surface seawater were used in control experiments. Fresh weights of G. chorda cultured in the different seawaters were measured and analyzed statistically. The statistical analysis showed that the fresh weight of the alga cultured in the Muroto deep seawater was significantly heavier than that cultured in surface seawater. After four weeks culture, algal fresh weight in deep seawater was about twice as heavy as that in surface seawater. Chemical analysis showed that the Muroto deep seawater contained large amounts of inorganic nutrients such as NO-3 (24.2-30.2μM) and PO3-4(1.50 2.00μM). Because algal fresh weight increased with the addition of two inorganic nutrients (final concentration: about 30 pm NO-3 and 2μm PO3-4) to surface seawater, such nutrients probably contribute to the grow th of the alga. The result suggests that the Muroto deep seawater is a more effective medium for the red alga, G. chorda, than any of the other seawaters tested.
