ARS | Publication request: The relative contributions of habitat quality and water quality to the integrity of aquatic communities in agricultural drainage ditches

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: February 9, 2007
Publication Date: July 23, 2007
Citation: Gillespie, R.B., Smiley, P.C., King, K.W., Huang, C. 2007. The relative contributions of habitat quality and water quality to the integrity of aquatic communities in agricultural drainage ditches [abstract]. Soil and Water Conservation Society. p. 48-49.

Technical Abstract: Agricultural drainage ditches comprise as much as 25% of total lotic habitat in the midwestern United States. Aquatic communities that inhabit drainage ditches of intensely-farmed landscapes are impacted by degraded structural habitat and water quality. Our hypothesis is the integrity of aquatic communities of drainage ditches is influenced more by structural habitat than by water quality. The Cedar Creek and Upper Big Walnut Creek are CEAP Benchmark Research Watersheds that comprise 350,000 acres of land dominated by agricultural land use in Indiana and Ohio. From 2005 to 2006, ecological assessments have been made at 20 study sites within these agricultural watersheds. Riparian width, vegetative species composition, and vertical structure were measured in each site to assess riparian habitat quality. Instream habitat quality was measured by quantifying water depth and flow, and determining substrate types. Water samples were collected with automated water samplers and/or grab-samples. Water quality was determined by measuring temperature, dissolved oxygen, pH, conductivity, and concentrations of suspended sediments, nutrients, and pesticides. Aquatic communities were assessed three times from May to October by sampling fishes and macroinvertebrates. Multivariate statistics will be used to evaluate the relative contribution of structural habitat quality and water quality to the structure of aquatic communities. These results will provide natural resource managers with information that can assist with the selection of conservation practices that will benefit aquatic communities in agricultural drainage ditches.