Master of Science
Robert B. Gillespie
Date of Award
Many agricultural drainage ditches in the Midwestern United States are degraded headwater streams that possess communities of crayfish. We hypothesized that crayfish communities at sites with low instream habitat diversity and poor water quality would show greater evidence of aggression. In this study eight sites on channelized headwater streams feeding Cedar Creek in Northeastern Indiana, nine sites feeding Upper Big Walnut Creek in Central Ohio, and one site on the East Branch of the Saint Joseph River in Southeastern Michigan were monitored over two years for evidence of crayfish aggression. All adult crayfish captured were identified to species, sexed, measured, and damaged appendages were scored as injuries. Data on instream habitat and water quality were also collected. Concentrations of nutrients and pesticides at all study sites were provided by scientists at The National Soil Erosion Research Laboratory. All sites surveyed had live captures of adult crayfish on at least one sample date. Four crayfish injury response variables were calculated; mean number of injuries per individual, proportion of injured individuals, mean number of claw injuries per individual and proportion of individuals with multiple injuries. Crayfish community density was calculated for each site. A habitat diversity index and a water quality index were developed to assess site quality. A mixed effects model multiple regression analysis was used to correlate site quality index values with crayfish behavior response variables. We found that only crayfish community density was significantly correlated with all four crayfish behavior response variables.
Tyler C. Wood (2016).
Influence of Instream Habitat, Water Quality, and Crayfish Density on Injury Frequency in Crayfish of Midwestern Channelized Headwater Streams.