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The Illinois River is the most important large-river watershed in the state. In January
1997, then Lieutenant Governor Bob Kustra presented to the state the Integrated Management Plan for the Illinois River Watershed. The plan was the result of more than a year of effort by 100 Illinoisans to suggest ways to save and restore this great river. They made 34 recommendations, many of which were designed to improve the ecology of the river and the production of fish and wildlife resources.

Eighty percent of the Illinois River watershed is in the state of Illinois, and 90 percent of the state's population lives in the 55-county watershed area. Demands on lands and waters in the watershed for agriculture, residential and industrial development, navigation, and a variety of recreational activities including fishing and hunting have all created at times conflicting demands on the watershed's resources. Sound scientific studies are needed to determine the effects of a variety of natural and anthropogenic activities, and to suggest management strategies that may lead to a more sustainable use of the river's resources.

A view of the Illinois River from Buffalo Rock State Park.









The Illinois Natural History Survey has had a significant presence on the river over the last century. The Forbes Biological Station on the Illinois River near Havana is our oldest field station and was formed in 1894. Two field stations were established to carry out the Long Term Resource Monitoring Program (LTRMP): one on the Illinois River at Havana and one on the Mississippi River, just below the confluence with the Illinois River at Alton. These were a result of a 1988 cooperative federal-state LTRMP, which established five study reaches and stations on the upper Mississippi River and one reach (La Grange) and station on the Illinois River to monitor and assess long-term trends in the natural resources of the upper Mississippi River system. Recently, two Survey research scientists were hired and stationed at the Midewin National Tallgrass Prairie (formerly the Joliet Army Arsenal) to oversee monitoring efforts and to conduct research related to prairie restoration. Our hope is to eventually study all aspects of the prairie ecosystem as it is being restored in this portion of the Illinois River watershed.

INHS scientists are contributing and planning a wide variety of research projects relevant to the conservation and restoration of the Illinois River watershed. These projects can be grouped into four general categories:

Historical ecology and restoration of biodiversity--Descriptions of presettlement conditions and historical data will provide information for restoration efforts and provide a benchmark for judging the biological integrity of an ecosystem or watershed.

Inventory and monitoring--New surveys of the few remaining relatively undisturbed habitats, focusing on neglected taxa, are needed to improve our understanding of the full range of biotic components that ensure the sustainability of these ecosystems. There is also a need to monitor populations and characterize their spacial and temporal abundance so that the results of various restoration and development activities can be determined.

Management effects--Protocols must be developed, evaluated, and improved to document changes in populations resulting from habitat/ecosystem restoration and specific management practices, and to facilitate the development and testing of models that predict the effects of management on the biota.

Ecology/genetics/ecosystem function--Basic research on ecosystem processes in the Illinois River system will be crucial if we are to understand the attributes of a functional, self-sustaining ecosystem. This research ranges in scale from the role of genetic diversity in the population viability of individual species to the entire complex of trophic interactions among all species present in the ecosystem.

Fishermen hauling in catch on the Illinois River near Havana about 1910.

The INHS is conducting a number of significant research projects related to the Illinois River watershed. For example, populations of waterfowl and other birds migrating through the Illinois River have been monitored each year for the last 50 years through aerial censuses. These data provide a useful index to waterfowl populations in the region and are indicative of wetland habitat quality and quantity in the system. Invasive species have had a significant impact on the Illinois River ecosystem, a recent dramatic example being the zebra mussel. One project presently funded by the Illinois/Indiana Sea Grant Program is examining how population dynamics of the zebra mussel in the Illinois River depends on dispersal of larvae from Lake Michigan. The hypothesis being explored is that by controlling dispersal, the population of zebra mussels in the river can then be controlled by reducing recruitment from Lake Michigan.

The La Grange Reach, with its extensive mosaic of backwaters, is among the most habitat-diverse reaches of the Upper Mississippi River System (UMRS). The La Grange Lock and Dam at river mile 80 and the Peoria Lock and Dam at river mile 158 define the diverse and historically significant La Grange Reach of the Illinois River. The La Grange Lock and Dam is the furthest downstream water level control structure along this commercially navigable waterway. This is the area where Stephen Forbes established a river research laboratory at Havana in 1894, 40 years prior to construction of the dams.

Since 1989, INHS scientists at the Havana Field Station have been monitoring fish, invertebrate, and vegetation communities along with water quality parameters of La Grange Reach as a part of the Long Term Resource Monitoring Program (LTRMP). These efforts represent the most intensive sampling regime ever conducted on this great river as our biologists collect physical, chemical, and biological data from backwaters, side channels, tributary mouths, the main channel, and tailwater areas seasonally. To date, these efforts have accounted for over 600,000 fish representing 83 species and 6 hybrids; 4,500 invertebrates representing 6 taxa; 11 submersed aquatic vegetation species; and a long-term record of 23 water quality parameters monitored throughout the reach on a biweekly basis throughout the year. In addition, Havana Field Station staff have been monitoring floodplain forest community composition, riverine zooplankton and zebra mussel veliger dynamics, and bioresponse to habitat rehabilitation projects, as well as conducting focused research studies for several state and federal agencies.

The fishes of La Grange Reach--Of the 94 fish species documented from the entire Illinois River waterway by INHS surveys since 1957, 83 species have been collected by the Fisheries Component of LTRMP during the past 10 years. The most abundant of these have been gizzard shad (Dorosoma cepideanum) and emerald shiner (Notropis atherinoides), which have comprised 51% and 8% of the total catch from La Grange Reach, respectively. These species form an ecologically important source of prey for several other sport and/or commercially fished species of the reach, such as white bass (Morone chrysops), largemouth bass (Micropterus salmoides), and channel catfish (Ictalurus punctatus). We also continue to collect and monitor the abundance of several non-native fish species. Some of these, such as common carp (Cyprinus carpio) and goldfish (,i>Carassius auratus), have been present since the early 1900s and are quite common in our samples; common carp ranked third in overall abundance and has comprised 7% of the total LTRMP catch. Other exotic species, such as grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), bighead carp (H. nobilis), and white perch (Morone americana), have only recently appeared in the Illinois River and their effects on the system are only beginning to be understood.

Illinois River viewed from Starved Rock State Park.

Habitat comparisons--Because the LTRMP takes a community approach to fish sampling and utilizes many different types of gears to gain a valuable assessment of fishes, we can make comparisons of our collections among the various habitat types of the reach. Overall, fish diversity has been greatest in contiguous backwater and side channel areas. Backwaters provide habitat and nursery areas for many, more typically lentic species such as bluegill (Lepomis macrochirus) and black crappie (Pomoxis nigromaculatus) throughout the year, and other riverine specialists (such as the ancient paddlefish, Polyodon spathula) seasonally. Side channels often hold large woody deadfalls and other debris, which are important for species such as smallmouth buffalo (Ictiobus bubalus) and flathead catfish (Pylodictis olivaris) throughout most of their life history. Main channel collections are dominated by only a few species and are typically much lower in diversity. These comparisons highlight the importance of our connected off-channel habitats to the river proper and emphasize the value of efforts to protect or even reestablish these areas.

The systemic view--What makes the La Grange LTRMP collections by the Havana Field Station unique are the abilities we have to compare our data with that of five other field stations located throughout the UMRS. Surprisingly, despite the long history of water quality and habitat degradation that the Illinois River waterway has experienced over the past century, many fish populations have faired very well. One example is the comparison of the number of channel catfish collected per hour by electrofishing (channel catfish are considered the most important sport/commercial species by our UMRS natural resource managers). At La Grange Reach, we collect an average of 10 channel catfish each hour of electrofishing compared to less than 3 channel catfish per hour in collections at LTRMP trend analysis areas Pools 4, 8, and 13 of the UMRS.

Bringing it all together-- The elegance of long- term datasets such as those being created by LTRMP is in our ability to relate annual variation in fish, invertebrate, and vegetation communities to regulatory factors working at large temporal scales. For example, staff at the Havana Field Station have related annual growth patterns of largemouth bass, bluegill, and freshwater drum (Aplodinotus grunniens) to large-scale hydrological factors. We have shown increased growth for these species and higher overall river productivity during flood years such as 1993 and 1995. More recently, we have been quantifying annual river hydrology in terms of timing, magnitude, frequency, and rates of change of annual pulse events. Correlating these ecologically meaningful hydrological parameters with variation in fish and vegetation communities will be useful in establishing biota friendly criteria for operations of the La Grange and Peoria Lock and Dams, while maintaining water levels for commercial navigation. We are also relating variation in water quality over the past several years with changes in biotic communities of La Grange Reach. These efforts will be extremely useful to assess any effects of the new Conservation Reserve and Enhancement Program (CREP) on the Illinois River and its floodplain. Only through long-term programs such as the LTRMP are studies of this type possible. As the national spotlight is focused on the great Illinois River, INHS researchers at Havana can assist area resource managers in answering complex questions about management of this large river floodplain ecosystem.

INHS ILLINOIS RIVER RESEARCH PROJECTS

* Tree regeneration and herbaceous understory dynamics in an Illinois River floodplain forest following stand mortality after the flood of 1993
A. Plocher

* Species composition and understory dynamics in floodplain forests of three Illinois rivers
A. Plocher

* The Thompson Lake Story; Its Biology, Drainage, and Restoration (INHS Bulletin)
S. Havera, K. Roat, L. Anderson, D. Esarey

* Strategic renewal of large floodplain rivers: integrated analysis
R.E. Sparks, D.W. Schneider, J. Braden, A. Isserman, D. Johnston, M. Demissie, D. White

* Long-term Illinois River Fish Population Monitoring Program
T.M. Koel, R.E. Sparks

* Long Term Resource Monitoring Program on La Grange Reach, Illinois River
T.M. Koel , K.D. Blodgett, R.E. Sparks

* Effects of dredged material placement on macroinvertebrate communities
T.M. Koel, K.E. Stevenson

* Survey of macroinvertebrates in Peoria Lake
T.M. Koel, K.E. Stevenson

* Lake Chautauqua Habitat Rehabilitation and Enhancement Project (HREP) larval fish production
R.E. Sparks, K.D. Blodgett, T.M. Koel, K.S. Irons, J.A. Stoeckel

* Peoria Lake HREP Fish monitoring
R.E. Sparks, K.D. Blodgett, T.M. Koel

* Upper Mississippi River Environmental Management Program, Lake Chautauqua HREP Post-Construction Biological Response Survey---zooplankton production
J.A. Stoeckel, T.M. Koel