| AbstractThis study examined the structure and function of habitat units as fish habitats, the contribution to fish populations, and the effects of channel modification on habitat unitsand fish populations in the lowland meandering Shibetsu River, northern Japan.Electrofishing and environmental measurements were conducted in bank areas of habitat units constituting natural meandering and modified reaches. All types of habitatunits in a meandering reach highly contributed to the fish population(s). In particular,the contributions of lateral and wood habitats to fish populations were generally high,despite the low spatial extent of these habitat units. The modified reach was simplifiedand had fewer types of habitat units with uniform currents, and there was a lowabundance of most fish within these units. Abundance of each fish group (taxa) wasnegatively affected by the changes to the habitat units and/or channel shortening (i.e.,decrease in the absolute abundance of habitat) due to river modification, which wasimplemented during 1950-1978. This study suggests that the recovery of sets of habitatunits is important in meander restoration and that the changes in habitat types andabundance should be examined in monitoring meander restoration and channelshortening. |
