Abstract
This study considered the controlling factors of winter diatom blooms in the inner western part of Ariake Bay. This study was based on observations（i）made over three seasons in the coastal area from2012to2015; and（ii）in the intertidal area from 2014 to 2015. Diatom blooms and nutrient exhaustion were observed in each season at Stn.1, located in the coastal area, when the temperature dropped below10℃. Results suggested that the intertidal area, where nutrients were supplied from the river, was important in allowing diatoms to maintain primary production ; this may have contributed to the occurrence and maintenance of blooms in the coastal area. These results revealed that diatom dynamics in the intertidal area are important in understanding
winter diatom blooms in coastal areas in the inner western part of Ariake Bay.
