摘要:The settlement pattern of barnacles, Balanus amphitrite amphitrite (Darwin) and oysters Crassostrea madrasensis (Preston) and Saccostrea cuccullata (Born) on the stilt roots of the mangrove tree Rhizophora apiculata (Blume) bordering the intertidal region of Pichavaram mangrove (Lat. 11° 27 N Long. 79° 47 E) has been studied with reference to the tidal oscillation. Vertically, settlement was found to be abundant on stilt roots occurring at low tide than at mid and high tide levels. This differential settlement could be attributed to the adaptability of these organisms to their tolerance to extended period of either tidal submersion or emersion. Vertically both the oysters settled preferably at the bottom of part stilt roots indicating their inability to tolerate long period of exposure. S. cuccullata occurred above the level of C. madrasensis suggesting that the former could tolerate comparatively a more extended period of exposure. Settlement was high during late post monsoon and early summer coinciding with the abundant of high phytoplankton, the optimal temperature and salinity, for the growth and breeding of these benthic organisms.