Biological and physical surveys were conducted at amacloalgae bed (MB) and a sandy beach (SB) off an inhabited island in the central Seto Inland Sea, Japan, from August 2006 tomay 2007 in order to detect the effect of vegetation on fish assemblage. Fish were collected using a seine net (2m in height, 3mm in mesh aperture) at four separate locations within MB and SB during a tidal level between 70-130 cm in daytime on 4 Aug. and 16 Nov. 2006 and 19 Feb. and 2 May 2007. A total of 1,397 and 902 fish were collected at MB and SB, respectively. The numerically dominant species were Sebastes cheni, Favonigobius gymnauchen and Hypodytes rubripinnis in MB and Favonigobius gymnauchen, mugil cephalus cephalus and Acentrogobius pflaumii in SB. Weight-based dominant species were Sebastes cheni, Hypodytes rubripinnis and Halichoeres poecilopterus in MB and Favonigobius gymnauchen, Sillago japonica and Mugil cephalus cephalus. Seasonal fluctuation in number of fish species, fish abundance and biomass in MB were larger than those in SB.
The number of fish species in August in MB was significantly higher than that in SB. Fish abundance and biomass in MB abruptly increased fromFebruary to May due to immigration of S. cheni larvae and juveniles.