Research Talk: Stream Energy Budgets | SFS 2021 Conference | Michelle Catherine Kelly
Channel: Michelle Catherine Kelly
Date: 2021-05-07

Website: https://michelleckelly.github.io/StreamEnergyBudgets/

Talk title: Are anaerobic energy-generation pathways significant contributors to stream energy budgets?

Authors: Michelle Catherine Kelly, Erin K. Eberhard, Kevin Nevorski, Amy M. Marcarelli, Michigan Technological University

Conference: Society for Freshwater Science Annual Meeting https://sfsannualmeeting.org/  

Abstract: While we focus on the aerobic processes of gross primary production (GPP) and ecosystem respiration (ER) to parameterize stream metabolism, we also know that anaerobic, energy-releasing processes are common in streams. Denitrification, which releases just 5% less free energy than aerobic respiration, is one such process. We ask: are anaerobic energy-generation pathways significant contributors to stream energy budgets? We measured denitrification (acetylene block) and aerobic metabolism in 25 study streams in the USA (NEON n=13, StreamPULSE n=12), modeling GPP and ER using a one or two-station inverse Bayesian approach. This dataset was supplemented with denitrification (15-N tracer) and metabolism from LINXII (n=28). Areal denitrification and ER rates were converted to rates of energy release using Gibbs free energy values. Total energy released was calculated as free energy from denitrification plus ER. Linear, nonlinear, and tree-based regression models, where the best fit model was determined by testing set performance, were used to determine which environmental variables were most important to predicting the proportion of the total energy budget released via denitrification. Preliminary results show denitrification contributing to as much as 9.6% of the total energy budget of a single stream.