Abstract
The total areas of the existing natural and reclaimed tidal flat in Ago Bay were estimated by multispectrum aerial picture analysis. Approximately 70% of the tidal flat and shallow areas have already been lost because of land reclamation and dyke construction. The sediment quality and characteristics of macrobenthos in the natural tidal flats (estuary, in front of and behind the dykes) were investigated in this study. The macrobenthos in the natural tidal flat in front of and behind the dyke was poor in organic matter, because these sediments were relatively oligotrophic in front of the dyke and hypertrophic behind the dyke. Thus it is considered that the reclamation by constructing the dykes was one of the major causes of the deterioration of the benthic ecosystem and decrease in the biological productivity of Ago Bay.
