SCUBA net analysis of species composition and spatial distribution of inhabitants of an open water eelgrass bed in the Seto [Japan] Inland Sea

To clarify the function of eelgrass beds in open waters, we performed continuous observations of an eelgrass bed formed in Zushi-ga-hama, in the Seto Inland Sea off the town of Suo-oshima in Yamaguchi Prefecture, Japan, by using a quantitative method called SCUBA Net. We examined the species composition and spatial distribution of fishes and their prey animals in the eelgrass bed. The fishes in this open-sea eelgrass bed used fewer fish species but more species of small crustaceans as live food than did the fishes at a sheltered eelgrass bed in one of the innermost bays of the Inland Sea. The finding that the habitat was much more varied inside this open sea eelgrass bed than outside it suggests that a rich variety of bioenvironments can be created in such open sea areas through the formation of eelgrass beds.