Location: Soil Drainage ResearchTitle: Relative importance of water chemistry and habitat to fish communities in headwater streams influenced by agricultural land use Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2012
Publication Date: 3/25/2013
Citation: Gillespie, R.G., Smiley, P.C., Sanders, K.E., King, K.W., Smith, D. 2013. Relative importance of water chemistry and habitat to fish communities in headwater streams influenced by agricultural land use. March 25-27, 2013, St. Louis, Missouri.Meeting Abstract. 2013 College of Food Agricultural, and Environmental Sciences Undergraduate Research Symposium, March 25-27, 2013, St. Louis, Missouri. Meeting Abstract. Interpretive Summary:
Technical Abstract: Channelized headwater streams are common throughout agricultural watersheds in the Midwestern United States. Understanding the relative impacts of agricultural contaminants and habitat degradation on the aquatic biota within agricultural headwater streams will provide information that can assist with the management of these streams. We have conducted annual ecological assessments of fishes, water chemistry, instream habitat, and riparian habitat in seven channelized headwater streams in central Ohio and three channelized headwater streams in northeastern Indiana since 2006. Additionally, biomarker surveys of three fish species were made at three channelized headwater stream sites and one reference site in both watersheds in 2011 and 2012. Streamside bioassays with fathead minnows (Pimephales promelas) were also completed over a two-year period (2010-2011) at the northeast Indiana sites. Although specific differences were found between the two watersheds, fish community structure was more strongly correlated with instream habitat than either riparian habitat or water chemistry. These fish-habitat relationships occurred across watersheds and within individual watersheds. Results from biomarker surveys suggested that fishes exposed to agricultural contaminants in channelized headwater streams have not experienced significant negative health effects nor exhibited evidence for reproductive endocrine disruption. Results from streamside bioassays suggested that long-term exposure to nutrients and atrazine may have caused negative impacts on growth in fathead minnows (Pimephales promelas). However, neither survival, hepatosomatic indices, nor gonadosomatic indices differed among treatment groups of fathead minnows. Analysis of water chemistry data showed that concentrations of agricultural contaminants, such as herbicides and nutrients were typically below benchmark levels capable of inducing chronic toxicity in fishes. In general, our results suggest that when water chemistry conditions are not limiting the ecological integrity of fish communities in channelized headwater streams will be more influenced by instream habitat degradation than by the toxicity of agricultural contaminants. Therefore, restoration projects that lead to improvements in physical habitat quality should result in positive changes in the fish communities within agricultural headwater streams in the Midwestern United States.