Spatial variation in headwater stream macroinvertebrate abundance and diversity : an honors thesis (HONRS 499)
We studied headwater streams in Delaware County, Indiana to quantify differences in macroinvertebrate assemblages and identify factors related to diversity of macroinvertebrates. We hypothesized that macroinvertebrate indices would differ with surrounding land-use as a result of physiochemical and hydrological properties. Weekly water samples and physiochemical measurements were collected from May-September 2008 in conjunction with macroinvertebrate samples collected using benthic surber samplers. Macroinvertebrates were brought back to the laboratory and identified to genus; macroinvertebrate indices were calculated for all sites. Percent Chironomidae/Oligochaeta, %Dominant Taxa, and Genera Richness all showed similar patterns among sites, while EPT differed little as a result of low numbers of Ephemeroptera, Plecoptera, and Trichoptera at all sites. Percent Chironomidael Oligochaeta abundance was correlated with pH. Low macroinvertebrate diversity is potentially due to agricultural and urban land-use in the surrounding watersheds. Low EPT values at all sites made it an ineffective index at detecting differences among sites and are indicative of highly degraded systems. Genera richness, percent dominant taxa, and percent Chironomidae/Oligochaeta were better indices at detecting changes in macroinvertebrate assemblages in these highly degraded watersheds.