Studies of coastal structures regarding their function as fish reefs

The influences of the establishment of coastal structures on local ecology were studied by catching or collecting algae, periphytic creatures, epiphyllous and interfoliaceous biota, and fish in the vicinity of breakwaters and, ascontrol, in sea areas free from influences of such structures.Biota in areas free from influences of coastal structures were compared with those from in front of breakwaters.Results showed that biota were more diverse among the latter group, with appearance of larger numbers observed ofboth population and species of fish and shellfish, which inhabit algae zones or rocks and conduct feeding andspawning migrations.Also, the results of comparison between the front and back sides of sloping breakwaters showed that the appearanceof a greater diversity of fish and shellfish was observed at the back sides. Appearance of fry bom from pelagicor periphytic eggs was only observed in the latter case.From these results, it was confirmed that the coastal structures function as places for fish together. More over, the back side of a permeable sloping breakwater can serve as a place for fish to spawn and fry to grow, due toattenuated wave conditions.