Comparative nursery habitat use by 0+ fish in a modified lowland river

The use of nursery habitats by 0+ fish in a lowland channelized and regulated stretch of the River Morava (Czech Republic), was assessed by electrofishing, using the point abundance sampling method. In the period 1991–1993, a total of 71 sites were sampled during late summer. Changes in the character of spawning sites and nursery habitats after channelization and regulation did affect the fish community structure. Shoreline nursery zones were reduced to only two basic mesohabitat types: boulder bank and sand–gravel beach. 0+ fish have limited habitat choice, but chi-squared analysis revealed some segregation of nursery areas. Generally, the dominant species did not show any habitat preferences (Rutilus rutilus), or preferences changed from year to year (Leuciscus cephalus, Gobio gobio and Rhodeus sericeus). Rare rheophilic species had more strict habitat requirements and used sand–gravel beaches as nurseries. Of the environmental variables studied (woody debris, vegetation, periphyton, silt and current), only areas with emergent vegetation played a significant role as nursery habitats. Copyright © 1999 John Wiley & Sons, Ltd.