In order to evaluate the effect of artificial rock solidified dredged soil on the organisms, we observed the appearance of diatoms, seaweeds, sessile/mobile animals, and fishes for about 2 years after setting the reef making a comparison with natural stone. And the nitrogen and carbon stable isotope ratios of the biological communities gathering on artificial reefs were compared with surrounding area.
For seaweeds, their appearances differed depending on the species, Sargassum horneri was detected on artificial stone, and Ecklonia cava tended to habit on natural stone. No clear difference was observed between the artificial rock and natural rock in the whole community structure of the sessile and mobile animals. In addition, difference among the taxonomic groups were also small from the viewpoint of appearance status resulting from the cluster analysis. However, comparing with the prey organisms in the stomach contents of fish, many Serpulidae, polycheats appeared in artificial rock. Some fishes preying on them like Acanthopagrus schlegelii and Oplegnathus fasciatus had a greater populations at prey-rich artificial rock, which suggests the relationship between biomass of prey organisms and population of fish. Although the species number of fish differed between artificial rock and natural rock, specific relationship was found neither in the raw materials, nor in biomass of prey and seaweed. The stable isotope ratios of nitrogen and carbon suggested that the artificial rock has a food linkage structure equivalent to that of the surrounding area.
