Abstract
In order to control water quality in a polluted semi-enclosed sea, it is important to monitor the amount of biomass especially based on phytoplankton. To investigate fluctuation of this biomass, we have carried out a long-term field measurement of chlorophyll-a in the Kaita Bay from 1999 to 2001, and examined data by using time-series analysis. The results indicated that the amount of chlorophyll-a from April to September fluctuate periodically in from 5days to 10days cycle, and the deviation of this fluctuation could influence the estimated biomass significantly. Also according to classification of phytoplankton in the Kaita Bay, diatoms seem to play the important role in this medium-term variation.
