Submitted to: Ecohydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2009
Publication Date: 3/13/2009
Citation: Smiley, P.C., Gillespie, R.B., King, K.W., Huang, C. 2009. Management implications of the relationships between water chemistry and fishes within channelized headwater streams in the midwestern United States. Ecohydrology. 3:294-302. Interpretive Summary: Conservation practices are management practices that are designed to reduce sediment, nutrient, and pesticide loadings to streams from agricultural activities. The effect of these practices on water chemistry and fish communities is unclear because the ecological impacts have not been evaluated. We examined the relationships among water quality, hydrology, and fish communities within agricultural drainage ditches in northeastern Indiana and central Ohio. The results suggest development of management plans that use a combination of conservation practices capable of addressing physical habitat and water chemistry degradation are most likely to provide the greatest benefits for fish communities within these impacted headwater streams. Our results have implications for designing management plans for agricultural drainage ditches (i.e., channelized headwater streams) in the midwestern United States.
Technical Abstract: Many headwater streams in the midwestern United States were channelized for agricultural drainage. Conservation practices are implemented to reduce nutrient and pesticide loadings within these altered streams. The impact of these practices is uncertain because the influence of water chemistry on stream communities is not well understood. We evaluated the relationships between water chemistry and fish communities within channelized headwater streams in Indiana and Ohio. Measurements of water chemistry and fishes have been collected from 20 sites beginning in 2005. Observed relationships between water chemistry and fish communities were weak, but significant (P < 0.05). Fish communities exhibited negative correlations with ammonia and nitrate plus nitrite and positive correlations with dissolved oxygen, pH, and metolachlor. The strongest observed relationships occurred within regression models that included nutrients, pesticides, and physicochemical variables. Our results suggest if water chemistry is the focus of a management plan, then the most effective conservation practices may be those that have a combined influence on nutrients, pesticides, and physicochemical variables. However, a management plan that addresses physical habitat and water chemistry degradation may provide the greatest benefits for fish communities within channelized headwater streams.