Abstract
In this study,we investigated the distribution of three semi-terrestrial crabs in Sennan-Satoumi Park in Osaka Prefecture, and gave management suggestions for conservation of those crabs. Semi-terrestrial crabs spend larval stage in the sea area, while juvenile and adult crabs inhabit coastal forests. The park was constructed at the Osaka Bay on natural coast by bay reclamation in 1996. Before the park was constructed, the crabs were commonly observed at the natural coast; however, after the reclamation project, since the project broke the continuity between the bay and the coastal forest, the less number of the crabs were found in the area. We investigated population and distribution of adult crabs and juvenile crabs in 2008. The populations of all three species were decreased and the activity patterns were changed by environmental changes, such as channel construction, compared with the data from previous study conducted in 2002. We also found that the adult crabs mainly inhabit near water, and the activity patterns of the juvenile crabs are affected by the continuity of coastal forest.Discontinuity of the coastal forest prevents juvenile crabs from migrating their habitat. In conclusion, in order to conserve the crabs, it is important to ensure the continuity of the coastal forest and preserve water holes in the park.
