Reproduced from Journal of Environmental Quality. Published by ASA, CSSA, and SSSA. All copyrights reserved. Macroinvertebrate Communities in Agriculturally Impacted Southern Illinois Streams: Patterns with Riparian Vegetation, Water Quality, and In-Stream Habitat Quality Mandy L. Stone,* Matt R. Whiles, Jeremy A. Webber, Karl W. J. Williard, and John D. Reeve ABSTRACT be applicable in many situations and regions (e.g., Lenat, 1988; Lang et al., 1989; Plafkin et al., 1989; Kerans and Relationships between riparian land cover, in-stream habitat, water Karr, 1994; Barbour et al., 1999). However, bioassess- chemistry, and macroinvertebrates were examined in headwater streams ment of freshwater habitats in a particular region often draining an agricultural region of Illinois. Macroinvertebrates and organic matter were collected monthly for one year from three inten- requires development of suitable methods and metrics sively monitored streams with a gradient of riparian forest cover (6, 22, based on knowledge of communities in specific systems and 31% of riparian area). Bioassessments and physical habitat analy- (e.g., Barton, 1996). ses were also performed in these three streams and 12 other nearby Agricultural runoff is a major contributor to degrada- headwater streams. The intensively monitored site with the least ripar- tion of aquatic ecosystems in the United States and ian forest cover had significantly greater percent silt substrates than has deleterious effects on stream water quality and in- the sites with medium and high forest cover, and significantly higher stream habitats (USEPA, 1994). The effects of agricul- very fine organics in substrates than the medium and high forested tural practices on streams include changes in riparian sites. Macroinvertebrates were abundant in all streams, but communi- vegetation, alteration of channel morphology, degraded ties reflected degraded conditions; noninsect groups, mostly oligo- in-stream habitats, and higher sediment and nutrient chaetes and copepods, dominated density and oligochaetes and mol- lusks, mostly Sphaerium and Physella, dominated biomass. Of insects, loads relative to unimpacted systems (Cooper, 1993). dipterans, mostly Chironomidae, dominated density and dipterans These impacts are apparent in streams that drain agri- and coleopterans were important contributors to biomass. Collector– culturally dominated landscapes of the U.S. Midwest, gatherers dominated functional structure in all three intensively moni- including Illinois, where approximately 80% of the land tored sites, indicating that functional structure metrics may not be surface is farmed (Illinois Department of Natural Re- appropriate for assessing these systems. The intensively monitored sources, 1994). site with lowest riparian forest cover had significantly greater macroin- In the past three decades, many studies have exam- vertebrate density and biomass, but lowest insect density and biomass. ined ways to minimize amounts of nutrients lost in ag- Density and biomass of active collector–filterers (mostly Sphaerium) ricultural runoff. Establishment of vegetated riparian decreased with increasing riparian forest. Hilsenhoff scores from all buffers of grasses, trees, and shrubs adjacent to water 15 sites were significantly correlated with in-stream habitat scores, percent riparian forest, and orthophosphate concentrations, and multi- bodies has become a widely accepted practice to reduce ple regression indicated that in-stream habitat was the primary factor nutrient and sediment runoff into streams (Peterjohn influencing biotic integrity. Our results show that these “drainage and Correll, 1984; Lowrance et al., 1985; Jordan et al., ditches” harbor abundant macroinvertebrates that are typical of de- 1993; Schultz et al., 1995; Dosskey, 2001). Research has graded conditions, but that they can reflect gradients of conditions shown that riparian buffer strips can significantly reduce in and around these streams. nutrients and sediment in overland flow, improve in- stream habitat, and in turn improve biotic integrity and thus ecosystem health (Todd et al., 1983; Dillaha et D ue to limitations associated with standard chemi- al., 1989; Osborne and Kovacic, 1993; Sweeney, 1993; cal monitoring programs and the inherent benefits Davies and Nelson, 1994; Vought et al., 1994; Naiman of biological assessments, the use of freshwater organ- and Decamps, 1997; Lee et al., 1999; Weigel et al., 2000; isms as indicators of environmental quality has recently Whiles et al., 2000). However, few studies have exam- increased (e.g., Abel, 1989; Rosenberg and Resh, 1993; ined riparian buffer effectiveness for reduction of nutri- Loeb and Spacie, 1994; Barbour et al., 1999). A wealth of ent and sediment movements into streams at the water- information regarding tolerances of macroinvertebrate shed scale (e.g., Jones et al., 2001), and the intensively taxa to various disturbances and pollutions exist (e.g., agricultural regions of Illinois are no exception (Illinois Hynes, 1960; Chutter, 1972; Hilsenhoff, 1987, 1988; Win- Department of Natural Resources, 1999). ner et al., 1980; Barbour et al., 1999), and this has given Given the general lack of information on aquatic com- rise to macroinvertebrate-based bioassessment methods munities found in the highly degraded streams that typ- that are sensitive to a variety of disturbances and may ify the agricultural U.S. Midwest, and the need for quan- titative information on relationships between riparian land use, in-stream habitat quality, water chemistry, and M.L. Stone, M.R. Whiles, and J.D. Reeve, Department of Zoology, Southern Illinois University, Carbondale, IL 62901-6501. J.A. Webber, biotic integrity, our objectives were to (i) characterize New Jersey Forest Service, P.O. Box 404, Trenton, NJ 08625-0404. and quantify aquatic macroinvertebrate communities in K.W.J. Williard, Department of Forestry, Southern Illinois University, streams of southern Illinois’ agriculturally dominated Carbondale, Illinois 62901-4411. Received 9 Aug. 2004. Technical Re- landscape; and (ii) identify riparian and in-stream fac- ports. *Corresponding author (mlstone@siu.edu). Abbreviations: AFDM, ash-free dry mass; CPOM, coarse particulate Published in J. Environ. Qual. 34:907–917 (2005). doi:10.2134/jeq2004.0305 organic material; EPT, Ephemeroptera, Plecoptera, and Trichoptera; FPOM, fine particulate organic material; VFPOM, very fine particu-  ASA, CSSA, SSSA 677 S. Segoe Rd., Madison, WI 53711 USA late organic material. 907 Published online April 20, 2005