PARENT SESSION
Poster Session #38: Landscape Ecology.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Macroinvertebrate assemblages of prairie headwater streams: effects of adjacent land uses.

Hall, Dianne¹, Bergthold, Brandy¹, Sites, Robert¹, Linit, Mark¹, ¹

ABSTRACT- Macroinvertebrates have long been used as indicators of water quality and, more recently, have been used to assess the impact of adjacent landuse practices. However, most of the recent research has focused on high gradient or higher order streams with gravel/cobble substrates. Our research examines the effects of adjacent land use practices on macroinvertebrate assemblages in three low gradient, headwater streams in the Prairie Region of Missouri that consist of mostly sediment/silt substrates. We sampled 16 sites on three streams in September, 1999. Each site was surrounded by forest, pasture or row crops. Significant differences in macroinvertebrate abundance, richness, and diversity among land uses and a strong interaction with reach location (up-, mid- or downstream) were revealed via ANOVA. Most variation in abundance and richness could be attributed to variations in water quality, based on Multiple Regression Analysis, whereas only a small amount of variation in diversity was attributable to water quality variables. Compositional differences between sites adjacent to different land uses and at different reach locations were revealed using Discriminant Function Analysis and compositional similarity among upstream sites, based on proportional abundances of species, was detected using Cluster Analysis. In summary, we have found significant differences in the abundance, richness, diversity, and composition of macroinvertebrate assemblages attributable to adjacent land uses. Ongoing research will allow for greater resolution of these relationships.

KEY WORDS: aquatic macroinvertebrates, land use effects, species diversity, stream ecology