EARLY HEARING DETECTION AND INTERVENTION VIRTUAL CONFERENCE
MARCH 2-5, 2021
(Virtually the same conference, without elevators, airplane tickets, or hotel room keys)
5/26/2021 | 8:30 AM - 10:30 AM | NITROGEN FIXATION AND DENITRIFICATION CO-OCCUR IN STREAMS ACROSS THE UNITED STATES | Virtual Platform
NITROGEN FIXATION AND DENITRIFICATION CO-OCCUR IN STREAMS ACROSS THE UNITED STATES
We conducted a cross-ecoregion study to test the hypothesis that N-fixation and denitrification will co-occur in streams across a range of reactive N concentrations. Between 2017 and 2019, we sampled 30 streams in 13 ecoregions, using chambers to quantify N2 flux using membrane inlet mass spectrometry, N-fixation using acetylene reduction, denitrification using acetylene block, and microbial assemblages using functional genes and taxonomic diversity. 25 of the study streams were part of the National Ecological Observatory Network or StreamPULSE, which provided data on water temperature, light, nutrients, discharge and metabolism. We found that N-fixation rates were detectable most frequently on rock, wood, and/or macrophyte substrates in around half of the streams surveyed. Denitrification potential was detected in all streams, with rates 1-2 orders of magnitude higher than N-fixation rates, and net N2 flux rates were positive, indicating net denitrification. Rates were not related to N concentrations, despite the common simplifying assumption that denitrification dominates under high N and N-fixation occurs under low N conditions. Additional analyses are exploring reach to watershed characteristics, and metabolic regimes as drivers of cross-ecoregion patterns in processes.
- Nutrient cycling
- Nutrients
- Ecosystem Dynamics
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Presenters/Authors
Amy Marcarelli
(), Michigan Technological University, ammarcar@mtu.edu;
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Erin Eberhard
(), Michigan Technological University , ekeberha@mtu.edu;
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Michelle Catherine Kelly
(), Michigan Technological University, mckelly1@mtu.edu;
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Kevin Nevorski
(), Michigan Technological University, kcnevors@mtu.edu;
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