FRESHWATER FISH ASSEMBLAGE ACCORDING TO MICROHABITATS CREATED BY A BARB-STRUCTURE IN A RIVER

Abstract

We examined whether a barb-structure can improve fish habitats by providing various physical environment and contribute to fish assemblage consist of various fish species by a field survey in the middle reach of the Katsura River, central Japan. Species diversity H’ of fish assemblage and coefficients of variance of depth and velocity in the barb-structure site were compared to those in two sites of the neighboring runs. Diversity of fish assemblage in the barb-structure site was higher than in the other two sites. Also, the barb-structure site had wider range of depth and velocity than that in the two sites, suggesting that diverse physical environment should contribute to diversity of fish assemblage there. Each fish species indicated each localization at subunit scale within the barb-structure site, according to their habitat preference and needs. Therefore, a barb-structure can support diversity of fish assemblage by providing suitable habitats to many species. Additionally, installation of a barb-structure should be more effective in a straight channel with narrow range of physical environment.