| Abstrakt: |
The suitability of rehabilitated floodplains along the lower River Rhine for rheophilic cyprinids was assessed by investigating the spatial distribution of 0-group fish among, and within, three newly created secondary channels, an oxbow lake reconnected at its downstream end and several existing groyne fields. Fish were sampled during April through September 19971999 with seine nets and trawls and, for each sample, the habitat (physical environment) was characterized (flow, depth, substrate and inundated terrestrial vegetation). The new water bodies provide more suitable habitats for 0-group fish than the groyne fields. Their beneficial value differs, however, between reproductive guilds and depends on the morphological and hydrological conditions. Total fish density increased along a gradient of decreasing water flow whereas the proportion of rheophilic species (Barbus barbus, Gobio gobio, Leuciscus idus and Aspius aspius) decreased. Flow velocity and water depth were the most important factors determining habitat utilization. Rheophilic fish were spatially separated from eurytopic fish (e.g. Abramis brama, Rutilus rutilus and Stizostedion lucioperca). During flood events, inundated terrestrial vegetation was an important habitat for the larvae of all species. To enhance the riverine fish community, floodplain water bodies should have complex shorelines, and a high variability of flow velocities. Their slopes should be moderate to maximize the probability of terrestrial vegetation getting inundated during spring and summer. Future management of similar floodplains should focus on more diverse and accessible aquatic habitats to increase overall fish species diversity, since different types of water body clearly have complementary values. Copyright © 2003 John Wiley & Sons, Ltd. |
Plný text