Ephemeroptera, Plecoptera, and Trichoptera (EPT) as indicators of stream health in Illinois.

R. E. DeWalt

In conjunction with the Illinois Critical Trends Assessment Program (CTAP: http://dnr.state.il.us/orep/inrin/ctap/ctaphome.htm), a program that documents current condition and trends in ecosystem health across the state, aquatic insect orders Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) (EPT) are being used as an indicator assemblage. Insects are more microscale specific in their habitat requirements that are fish; therefore, they make for a complementary index to fish sampling in streams. Randomly chosen sites provide CTAP with a way of determining the condition of Illinois streams on the broadest possible scale. Up to 150 streams will be sampled over a five year period, with resampling taking place beginning in the sixth year. Available data indicate that basins with high human population densities or heavy agricultural development have lower EPT richness than do wooded areas. Organic enrichment is apparent in some of the Rock River tributaries. Riparian and in-stream habitat has been altered dramatically across the state, especially so in highly urban and in agricultural areas. CTAP is poised to describe, for the first time, the condition of streams across the state, and to measure any changes in them in the future.

Comparison of historical and contemporary EPT assemblages across Illinois.

R. E. DeWalt, D. W. Webb

The large and comparatively old INHS collections of the aquatic insect orders Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) (EPT) provide a unique opportunity to compare historical and contemporary EPT fauna in Illinois. Most effort recently has focused on stoneflies. A comparison of the response of two stonefly genera in the state has produced the following results. The genus Perlesta is surprisingly diverse, being composed of eight species. All appear to be maintaining or increasing diversity (one is most likely a recent immigrant) over the course of the century. The genus Neoperla, also diverse with seven species historically, has lost 4 species, has had a range reduction in two species, and one species appears to be maintaining its population in a restricted part of the state. Perlesta spp. have an egg diapause that limits their exposure to low dissolved oxygen and high summer water temperatures, while Neoperla do not diapause which leaves their nymphs exposed to the worst conditions in Illinois streams. Other taxa are expected to show such responses, and the data entry of all our EPT specimen records will drastically improve our ability to make comparisons.

Reference stream characterization in the Northeastern Morainal Division of Illinois.

R. E. DeWalt

Currently, Illinois is unable to describe, in a quantitative fashion, what is high quality for streams in any region of the state. An effort is underway to identify and characterize wadeable streams in the greater Chicago area using the Critical Trends Assessment Program (CTAP: http://dnr.state.il.us/orep/inrin/ctap/ctaphome.htm) protocols. This project is a partnership between the INHS, the RiverWatch volunteer monitoring program, and the Chicago Wilderness (http://www.chiwild.org/biodiversity.html), a >100 member consortium of enviromnental organizations in the Chicago Area. Available data suggest that while relatively high EPT richness and habitat quality are still found in pockets of highly protected habitat, most species are moderately tolerant of a suite of watershed disturbance problems. The potential for return of the historicaly known, highly sensitive species is limited due to the isolated nature or the stream reaches and distance to high quality recolonization sources.

Comparison of volunteer stream monitoring data (Illinois RiverWatch program) to professional monitoring data (CTAP).

R. E. DeWalt, B. Barber, S. Fuller

The use of volunteer data for monitoring changes in ecosystems is a contentious subject for some scientists. Most volunteer monitoring programs have been developed with education and constituency building as their primary goal. Monitoring conducted by Illinois' EcoWatch Network has as its primary goal the gathering of data to inform management and policy decisions. Close working relations with professionals at the INHS have helped to develop a program to meet this goal. Quality assurance measures involving direct comparisons of RiverWatch volunteer and CTAP professional stream data have ongoing for three years (1998-2000). Initial results suggest that RiverWatch volunteers need improvement identifying certain organisms, that they should adopt a multiple indicator approach to assigning quality, and that they should modify the Macroinvertebrate Biotic Index to make it a more sensitive indicator. It appears that other parameters such as total taxa richness and an EPT richness measure might prove useful for modeling professional monitoring data in the future.

Caddisfly fauna of Split Rock Brook in Pecumsaugan Creek and Blackball Mine Nature Preserve, Utica.

R. E. DeWalt

Split Rock Brook is a springfed stream in the Pecumsaugan Creek/Blackball Mine Nature Preserve along the towpath of the Illinois and Michigan Canal 2 miles west of Utica. The caddisfly fauna was well documented by H. H. Ross in 1940.. It is the type locality for one microcaddisfly species and is the only Illinois location for a trumpet-net spinning caddisfly. The contemporary fauna is being documented through monthly sampling and will provide growth histograms for all caddisfly species present. The stream is dominated by two case-building caddisflies which occur in tremendous numbers. One species, due to the ameliorating effect of the spring source on water temperature, emerges in nearly every month of the year, where other studies in intermittent streams showed it to emerge in the fall only. It appears that two species of microcaddisflies and the trumpet-net caddisfly no longer live in the stream. Water samples have not indicated any recent contamination by major agricultural pesticides.

Aquatic macroinvertebrates as indicators of landuse change in Upper Mackinaw River tributaries

R. E. DeWalt, T. Tear, M. Herbert (TNC).

The response of fauna to restoration of a watershed is not well known. It is especially difficult to predict in large agricultural regions where sources for recolonization of sensitive taxa, and hence measurable improvement, are limited. To characterize faunal changes in a restoration project, two adjacent watersheds in the upper Mackinaw River basin were chosen in May 1999 as treatment and control streams to monitor for 5+ years. The sampling regimen is build to yield data for pretreatment and post-treat intervals. The treatment stream will experience removal of cattle from the drainage, building of a wetland to trap sediment and to process excess nutrients, and expansion of the width of the buffer strip. This project is just underway and little definitive data can be offered at this time.

Winter stoneflies of Illinois.

R. E. DeWalt, D. W. Webb, T. N. Kompare

During the past winter, field collecting of the winter stoneflies in Illinois was completed. Over the past nine years 1,594 sites in Illinois have been sampled for specimens of winter stoneflies. The localities of these sites have been georeferenced and the specimens collected have been identified and their associated information entered into a database. It is now possible to search this database on the web. This study will evaluate the changes in the distribution of winter stoneflies in Illinois relative to distribution patterns recorded prior to 1946, from 1946 to 1975, and from 1976 to 2000. A manuscript, "The winter stoneflies of Illinois (Insecta: Plecoptera): Changes in the past 100 years", is near completion and will be submitted to the Illinois Natural History Survey Bulletin for publication.

Leafhopper diversity of Illinois remnant prairies.

C. Dietrich

Leafhoppers (Cicadellidae) are the most speciose family of prairie herbivores, with many species restricted to relatively undisturbed prairie habitats. Many native species have declined dramatically and at least six European species have become established in Illinois since the original leafhopper inventory was completed by the INHS in the 1930s. The goal of this long-term study is to elucidate the conservation status of native leafhopper species and to monitor the effects of prairie management on leafhopper populations.

Long term monitoring of insect populations in Illinois.

C. Dietrich, M. Biyal

Due to their tremendous species diversity, ubiquity, and sensitivity to various environmental disturbances, insect assemblages are exellent indicators of habitat quality. As part of the Critical Trends Assessment Project (CTAP) quantitative data on terrestrial insect species richness and composition are being comiled annually for forests, wetlands and grasslands throughout Illinois. CTAP is the first state-sponsored conservation monitoring program to incorporate extensive data on terrestrial insect diversity.

Spatial and temporal analyses of the bacterial fauna and water, sediment, and amphipod tissue chemistry within the range of Gammarus acherondytes.

S. J. Taylor, D. W. Webb, S. V. Panno (Illinois State Geological Survey)

The federally endangered Illinois Cave Amphipod, Gammarus acherondytes, (Amphipoda: Gammaridae) is known only from shallow karst groundwater in a few small drainage basins of Monroe and St. Clair counties, Illinois. We are conducting amphipod tissue bioassays for pesticides; and examining groundwater bacterial diversity and abundance; and examining groundwater and sediment chemistry (including pesticides and heavy metals) and in four caves in Illinois' Salem Plateau. Row crop agriculture, livestock, private septic systems, and urbanization have been identified as potential contributors to groundwater contamination in this area. Monthly water samples are analyzed for cations, anions, heavy metals and pesticides, and continuous data logging over a one year period is providing detailed seasonal data and information on the response of water quality parameters to flood pulses. Significant differences in pH and dissolved oxygen levels among caves, and generally high levels of fecal coliform bacterial contamination, suggest that human impacts are having a negative effect on groundwater quality. Results of these investigations will clarify the nature and extent of these threats, and provide essential information needed to develop a recovery plan for this species.

Microdistribution of subterranean Amphipoda (Crustacea) of Illinois' Salem Plateau.

S. J. Taylor, D. W. Webb

Almost nothing is known about microhabitat use, seasonal population trends, and the life history of the federally endangered Illinois Cave Amphipod, Gammarus acherondytes, (Amphipoda: Gammaridae). To improve our understanding of this Illinois endemic, we are examining microhabitat use by this and other amphipods inhabiting caves in Monroe and St. Clair counties, Illinois. Monthly sampling will provide life history information, which is being coupled with analysis of cave stream gravel size distributions in relation to amphipod diversity and abundance. Experiments were also conducted on sediment size preferences in one of these caves. These data will be used to help develop a recovery plan for this species.

Distribution of Illinois semiaquatic bugs.

S. J. Taylor, J. E. McPherson (SIU)

The distribution of semiaquatic bugs (water striders and related families) in Illinois is being documented through field collections and examination of museum material. Keys to more than forty-five species are being developed. Current efforts focus on filling gaps in the known distributions of species and collecting data on microhabitat use and species associations. Several species not previously reported from Illinois have been collected during the present study. A computer database of Illinois semiaquatic bugs and distributional maps for these species are also being developed. This study will provide a useful too for the identification and conservation of these insects.

Habitat selection by migrating aphids.

D. Voegtlin, C. Favret

Flying aphids are collected using suction traps located about 30 meters apart in adjacent cultivated and perennial habitats. A comparison of the catches reveals that in spite of their small size and the fact that they are carried much like plankton on the wind, many aphid species are very effective at arriving in one of the two habitats. Three years of data has been analyzed and submitted as a masters thesis by Colin Favret. Trapping continues as part of a long term database on flight phenology, and abundance of aphids in central Illinois.