1Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, 2Department of Biology, Faculty of Science, Toho University, Funabashi, Chiba 274-0072, Japan
Sampling surveys were conducted at 15 stations in Tokyo Bay, Japan, in order to examine the change in spatial distribution with development for larval Japanese mantis shrimp Oratosquilla oratoria (Stomatopoda, Squillidae). All of the eleven larval stages of O. oratoria were collected, however, the larvae in the terminally additive stages did not occur throughout the research period. The propelagic-stage larvae (Stages I and II) occurred only in the southern part of the bay, which is the main spawning ground of O. oratoria, whereas the distribution of the pelagic-stage larvae (Stages III to XI) expanded towards the inner part of the bay with development. During the period when larval O. oratoria occurred in Tokyo Bay, the oxygen-depleted water frequently appeared at the bottom especially in the inner part of the bay. Although the distribution and mortality of the larvae were considered to be sensitive to dissolved oxygen-depleted water, the final-stage (Stage XI) larvae occurred in almost the whole area of the bay. These results suggest that O. oratoria larvae settle in a wide area of Tokyo Bay.