Cooperative Research Units
Education, Research And Technical Assistance For Managing Our Natural Resources
Home | Intranet | Digital Measures | Help

Mullen, J. A., R. G. Bramblett, C. S. Guy, A. V. Zale, and D. W. Roberts. 2011. Determinants of fish assemblage structure in northwestern Great Plains streams. Transactions of the American Fisheries Society 140:271-281.


Prairie streams are known for their harsh and stochastic physical conditions, and the fish assemblages therein
have been shown to be temporally variable. We assessed the spatial and temporal variation in fish assemblage
structure in five intermittent, adventitious northwestern Great Plains streams representing a gradient of watershed
areas. Fish assemblages and abiotic conditions varied more spatially than temporally. The most important variables
explaining fish assemblage structure were longitudinal position and the proportion of fine substrates. The proportion
of fine substrates increased proceeding upstream, approaching 100% in all five streams, and species richness declined
upstream with increasing fine substrates. High levels of fine substrate in the upper reaches appeared to limit the
distribution of obligate lithophilic fish species to reaches further downstream. Species richness and substrates were
similar among all five streams at the lowermost and uppermost sites. However, in the middle reaches, species richness
increased, the amount of fine substrate decreased, and connectivity increased as watershed area increased. Season and
some dimensions of habitat (including thalweg depth, absolute distance to the main-stem river, and watershed size)
were not essential in explaining the variation in fish assemblages. Fish species richness varied more temporally than
overall fish assemblage structure did because common species were consistently abundant across seasons, whereas rare
species were sometimes absent or perhaps not detected by sampling. The similarity in our results among five streams
varying in watershed size and those from other studies supports the generalization that spatial variation exceeds
temporal variation in the fish assemblages of prairie and warmwater streams. Furthermore, given longitudinal
position, substrate, and stream size, general predictions regarding fish assemblage structure and function in prairie
streams are possible.


Current Staff

Federal Staff: 98

Masters Students: 230

Phd Students: 144

Post Docs: 54

University Staff: 248

5 Year Summary

Students graduated: 647

Scientific Publications: 1894

Presentations: 4159



April (2nd Quarter/Spring) 2011

Unit Authors

Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey