The influence of hypoxic water on the early growth rate of the ark shell Scapharca kagoshimensis was examined at six stations, representing different hypoxic environments, in Mikawa Bay. New recruits of S. kagoshimensis appeared from late August to early October at each station. However, the growth rates thereafter differed among the stations; the maximum difference in growth rates among stations was fivefold. The growth rates were closely related to dissolved-oxygen saturation, so it is probable that hypoxic water strongly reduces the early growth rate of S. kagoshimensis in Mikawa Bay.
