河口域塩性湿地に生息する稀少カニ類シオマネキの生息場所利用

抄録

A field study was conducted for spatial distribution and movements of burrow locations of the fiddler crab Uca arcuata in the estuary of the Katsuura River, Tokushima Prefecture, western Japan. The crabs inhabited the upper intertidal zone of reed (Phragmites australis) marshes to bare mud flat. Large crabs were found widely throughout the distributional range, whereas small crabs and ovigerous females tended to occur in the upper area of the habitat, near the lower edge of reed marsh. In the non-breeding season both males and females foraged in similar frequency in all areas of the habitat. In the breeding season, however, males foraged less frequently than females, and exhibited waving display more frequently in the upper non-vegetated area than in other areas. A tracking survey of marked crabs for 28 days revealed that the males held the same burrows for average 4.7 days with the maximum 16 days and females for average 5.5 days with the maximum 14 days. The movement distances of the burrow locations by each crab were less than 4m.