2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/22/2018 | 3:15 PM - 3:30 PM | INTERACTIVE EFFECTS OF TEMPERATURE AND NUTRIENTS ON STREAM BIOFILM STRUCTURE AND FUNCTION | 321

INTERACTIVE EFFECTS OF TEMPERATURE AND NUTRIENTS ON STREAM BIOFILM STRUCTURE AND FUNCTION

The interactive effects of climate warming and eutrophication are poorly understood. In particular, we lack understanding of how the quantity and stoichiometry of nutrient supply shapes ecosystem responses to warming. We conducted three successive stream-side channel experiments in the southwestern region of Iceland that manipulated water temperature (8°C-25°C) as well as nitrogen (N; 0-200 ug/L) and phosphorus (P; 0-200 ug/L) supplies and ratios (N:P; 0.02-40 M). On the basis of previous research, we predicted that N supply rate and N:P stoichiometry would control biofilm assemblage structure, N₂-fixation rates, and gross primary production (GPP). We found that N₂-fixation increased with temperature (71-fold over the experimental temperature range), decreased with N supply rate (44-fold over the N treatment gradient), and shaped the temperature dependence of GPP. Surprisingly, P supply and N:P ratio did not influence N₂-fixation or ecosystem metabolism, suggesting that P supply was not limiting in this system even at high N supply rates and ratios. Our results highlight the importance of considering both nutrient supply rates and ratios, as well as limiting conditions, when predicting ecosystem responses to warming.

Nutrients
Climate Change
Metabolism

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Presenters/Authors

Lyndsie Collis (), The Ohio State University, collis.21@buckeyemail.osu.edu;