1. Large River Fish ~ 10,000 species > 2,000 species in Amazon (not all unique) Ancient freshwater fishes are river fishes

3. Factors Influencing Distribution/Diversity Current Velocity Substrate Refugia Habitat –“normal” –Spawning –Seasonal Biodiversity

11. Raibley et al. (1997) Winter habitats used by largemouth bass in the Illinois River. N. Amer. J. Fish. Mgmt. Radio-tagged fish in Illinois River Tracked through different seasons and electroshocked

12. Most winter sites are man-made. Why?

14. Wintering Sites Current velocities lower –Winter site 2 cm/sec –Channel 19 cm/sec Temperatures higher –Springs –Industrial outflows Dissolved oxygen remains high

15. Most winter sites are man-made. Why?

16. Boys and Thoms (2006) A large-scale hierarchical approach for assessing habitat associations in large dryland rivers. Hydrobiologia Effects of scale on distribution and diversity of fishes

18. Zone 1 very different Zones 2 and 3, not zone 4 fewer fish, higher abundance native species Zone 2 distinct from all other zones fewer native fish, more non-native species

19. Zone 3 very different Zones 1 and 2, not zone 4 High abundance of some natives and carp Zone 4 fish composition highly variable; greatest species richness of all zones

22. Valdez et al. (2001) Effects of a test flood on fishes of the Colorado River in Grand Canyon, Arizona. Ecological Applications 11:686-700. Extensive loss of beach and slackwater habitats since dam construction Managed flood used to rebuild these patches Examined response of fish

24. Figure 2 Why no difference in fish abundance before and after flood?

27. BUT, What about other aspects of hydrology? Five aspects of river flow (Poff et al. 1997) Colorado River – predictable flood pulse, relatively low intraannual variability Plains rivers – greater hydrological variability

28. Adams et al. (2004) Spatial and temporal patterns in fish assemblages of upper coastal plain streams, Missississippi, USA. Hydrobiologia 528:45- 61. Examined fish assemblages in a hydrologically variable river

30. Community dominated by “colonizing assemblages” – r-selected taxa

31. Same Pattern for Plains Rivers (Kansas R.) Dominant taxa –Small Cyprinidae (Notropis, Cyprinella, Macrhybopsis, Hybognathus) –Fundulus –Other small-bodied, short-lived taxa Rare taxa –Piscivores –Large omnivores (e.g., Ictiobus)