PARENT SESSION
Oral Session # 82: Aquatic Ecology: Freshwater.
Presiding: A Soja
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 200.
Long term monitoring design and spatial variation of fish communities in the upper Mississippi River basin.
Chick, John*,1, Pegg, Mark2, Koel, Todd3, 1 Illinois Natural History Survey, Brighton, Illinois, USA2 Illinois Natural History Survey, Havana, Illinois, USA3 National Park Service, Yellowstone National Park, Wyoming, USA
ABSTRACT- Since 1991, researchers with the Long Term Resource Monitoring Program have collected fish abundance and composition data from six regional trend areas (RTA) in the Upper Mississippi River System (UMRS): Mississippi River navigation pools 4, 8, 13, and 26, the La Grange pool of the Illinois River, and an open river reach on the Mississippi River near Cape Girardeau, MO. These six RTA were chosen to represent the range of conditions present throughout the UMRS and are meant to allow for system wide inferences about fish population and community dynamics. To test the adequacy of these six RTA in representing the variation of fish communities present in the UMRS, additional sampling was conducted during 2000 from areas above and below (out-pools) three RTA, and from navigation pools 19 and 20. Cluster analysis and non-metric multi-dimensional scaling of species composition (presence absence) and community structure (catch per unit effort) data revealed two major spatial groups of pools, and four sub-groups. Northern and southern pools formed the two major pool groups. The sub-groups identified included open river reaches, southern pools, northern pools, and the La Grange reach of the Illinois River. Out pools generally grouped with the closest RTA, but pools 19 and 20 grouped with southern pools in terms of species composition, and with northern pools in terms of community structure. Similarity among pools was correlated strongly with distance between pools, suggesting that zoogeography, regional disturbance patterns, and demographic processes (immigration/emigration, source sink dynamics, etc.) have important influences on fish communities. Correlations between community structure and composition with various habitat measures were not as strong as correlations with distance between pools. This analysis suggests the six RTA design of the Long Term Resource Monitoring Program may be adequate to capture the major spatial differences in fish communities within the UMRS. Nevertheless, additional research is needed to clarify how fish communities in pools 19 and 20 contrast with other areas in the UMRS.
Key words: upper mississippi river system, long term resource monitoring program, fish community composition, fish community structure