Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2008
Publication Date: September 3, 2008
Citation: Gillespie, R.B., Smiley, P.C., King, K.W., Huang, C. 2008. Relationships Among Macroinvertebrate Community Variables and Water Quality Parameters in Modified Agricultural Receiving Streams in the Midwestern United States. Meeting Abstract. Technical Abstract: Many headwater streams in the midwestern United States have been highly modified to receive agricultural drainage. Effective implementation of conservation practices to reduce nutrient and pesticide loadings requires information about the influence of water quality on biotic communities. We evaluated the relationships among water chemistry, physicochemical variables, and aquatic macroinvertebrate communities in highly modified agricultural receiving streams in Cedar Creek, Indiana and Upper Big Walnut Creek, Ohio. A total of 32 samples of water quality, physicochemical variables, and macroinvertebrate community characteristics were collected from 20 sites in 2005 and 2006. These highly-modified agricultural receiving streams were numerically dominated by snails, bivalves, and chironomids. Preliminary multiple regression analyses suggested that macroinvertebrate communities were more strongly correlated with nutrients than either pesticides or physicochemical variables. Specifically, taxa richness (r2= 0.651; P < 0.05) and percent Chironomidae (r2= 0.507; P <0.05) were strongly correlated with mean nitrate-nitrite concentrations, while percentage EPT was strongly correlated (r2= 0.894; P < 0.05) with soluble reactive phosphorus concentrations. Our results suggest that nutrients are more likely to have a greater impact on macroinvertebrate communities than pesticides and physicochemical variables. Thus, conservation practices designed to reduce nutrient loadings within channelized streams are likely to have a positive impact on macroinvertebrate communities in highly-modified agricultural receiving streams in the midwestern United States.