Quantifying the rate of denitrification in different stream components of a 4th order stream

First Author's Department

Biological Sciences

Second Author's Department

Biological Sciences



Document Type



Nitrogen is an important macroelement essential for life. Denitrification is an important step in the nitrogen cycle which microbially converts nitrate to nitrous oxide (incomplete denitrification) or di-nitrogen gas (complete denitrification). Denitrification is ecologically significant in streams as it can help in mitigating the amount of nitrate transport downstream. In this study, conducted in summer 2018, we examined the rate of denitrification in various stream components (sediment, water and macroinvertebrates). Freshwater macroinvertebrate guts have been shown to be a site for denitrification in prior research works. For the purpose of the study two sites in the West Branch of the Mahoning River (in Jennings Woods) were chosen. Macro-invertebrates that were sampled include crayfish, mayfly, caddisfly and members of Athericidae. Rate of denitrification was measured with and without acetylene block treatment. Each component (sample) was replicated thrice per treatment except caddisfly and mayfly samples due to lack of sufficient individuals that could be obtained from the respective sites. Caddisfly and mayfly samples were used only for the study with acetylene block treatment. Rate of denitrification was statistically significant among samples in both the sites and between the two different treatments. Sample, site, interaction between sample and site and the interaction between sample, site and treatment were also statistically significant. The future goal is to study the functional genes associated with denitrification in the various stream components and perform 16S gene sequencing to gain insight regarding the microbial community present in the various stream components.