The effects of water and habitat quality on amphibian assemblages in agricultural ditches
Abstract
Agricultural drainage ditches represent the headwaters of most watersheds in the Midwest. Constructed to improve agricultural productivity, there has been little attention given to their role in providing habitat to freshwater biota. The purpose of my study was to examine the relationship between the composition of amphibian assemblages that use ditch systems and water and habitat quality in a portion of the Cedar Creek watershed in northeastern Indiana and the Upper Big Walnut Creek Watershed in Ohio. Instream habitat, water chemistry, and amphibian assemblages were characterized at 14 sites sampled three times per year for two years. Principal components analysis was used to identify variables that contributed most to variation within habitat and water quality categories. Axes identified were then regressed against measures of amphibian abundance, diversity, and assemblage composition. Overall, amphibian assemblage variables were most correlated with measures of instream habitat. Streams with high velocity and discharge had lower abundance and species diversity. Although there was identifiable variation among sites in water chemistry, axes were not associated with any measure of assemblage structure. Parallel results from fish assemblages in the same system suggest that management for enhanced habitat quality should be prioritized when applying conservation practices.
Degree
M.S.
Advisors
Jordan, Purdue University.
Subject Area
Ecology|Hydrologic sciences
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