EARLY HEARING DETECTION AND INTERVENTION VIRTUAL CONFERENCE
MARCH 2-5, 2021

(Virtually the same conference, without elevators, airplane tickets, or hotel room keys)

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5/26/2021 | 8:30 AM - 10:30 AM | QUANTIFYING THE ROLE OF SUBSTRATE AND BIOFILM COLONIZATION IN CONTROLLING NITRIFICATION RATES USING EXPERIMENTAL STREAMS | Virtual Platform

QUANTIFYING THE ROLE OF SUBSTRATE AND BIOFILM COLONIZATION IN CONTROLLING NITRIFICATION RATES USING EXPERIMENTAL STREAMS

While nitrogen fertilizer is essential for agriculture, it often moves into waterways when applied in excess. Microbially-mediated nitrification rapidly converts fertilizer-derived ammonium to nitrate, which contributes to eutrophication. Substrate homogenization and riparian canopy clearing are also common in agricultural streams, but we lack understanding on how they alter nitrification. We assessed the influence of substrate (course vs. fine) and biofilm colonization (light vs. dark) on nitrification rates. We conducted replicated short-term ammonium additions in experimental streams containing different benthic substrates (i.e., sand, pea gravel, cobble, mixed) to estimate reach-scale ammonium uptake and nitrate production, combined with laboratory assays to estimate nitrification potential. Ammonium demand (as uptake velocity, Vf) differed among substrates and with biofilm colonization, and was highest on coarse substrates (cobble, pea gravel) under open canopy (ANOVA, p<0.001). We also documented reach-scale nitrate production for about half of ammonium releases, with highest production on mixed substrate under dark conditions. Assay nitrification rates were highest on pea gravel (p<0.001), but there were no differences between light vs. dark biofilms. Thus far, results suggest complex interactions between substrate type and biofilm colonization, but both contribute to nitrification dynamics in small streams.

Nutrient cycling
Nutrients
Stream

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Presenters/Authors

Anna Vincent (), University of Notre Dame, avincen5@nd.edu;