THE DAILY SETTLEMENT OF THE MEGALOPAE OF THE GRAPSID CRAB, PLAGUSIA DENTIPES DE HAAN(BRACHURA: GRAPSIDAE) IN RELATION TO ENVIRONMENTAL FACTORS

Abstract

The settlement mechanism of Plagusia dentipes megalopae to the intertidal zone of rocky shore was investigatec. The megalopae and crabs were collected by hand every three days from April to June 1 2, 1990. To detect the main mechanism by which the megalopae were driven to the intertidal habitat from offshore, the following weather and tidal conditions were recorded: the lunar cycle, surface water temperature, wind direction and velocity. There was no apparent relationship between the number of megalopae that settled and the lunar cycle or the water temperature. Whereas, there existed strong relationship between settlement of megalopae and the prevailing north wind.