Abstract
The purpose of this study is to clarify the effects of submerged breakwater on an artificial tidal flat ecosystem. The studied tidal flat ecosystem is composed of three zones, that is, low-, high-and no-submerged-breakwater zones.
The frequencies of shear stress being higher than the critical value (0.1N m-2) for silt transport in the low- and high-submerged-breakwater zones were lower than that in the no-submerged-breakwater zone. The silt and organic carbon contents in the low-and high-submerged-breakwater zones were higher than those in the no-submerged-breakwater zone. The slopes, reduction zone and permeability of sediment in the submerged breakwater zones were almost the same as those in natural tidal flats at Hiroshima Bay. However, the no-submerged-breakwater zone showed a sharper slope. The total population density of macrobenthos in the low-and high-submerged-breakwater zones were about twice as high as that in the no-submerged-breakwater zone. The dominant macrobenthic species in the submerged breakwater zones were Ceratonereis erthraeensis and Mediomastus sp., which are common in natural tidal flats at Hiroshima Bay. These results suggest that the construction of submerged breakwaters could change both the physiochemical and biological properties of artificial tidal flats similarly to those of natural tidal flats at Hiroshima Bay.
