2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
5/23/2019 | 2:00 PM - 2:15 PM | CARBON CYCLING IN STREAMS | 251 AB
CARBON CYCLING IN STREAMS
Soils are currently leaching out their organic matter at an increasing pace in aquatic ecosystems. The implications for stream biogeochemistry and food webs remain largely unknown, notably the metabolic balance (biotic CO2 emissions) and reciprocal subsidies between primary producers and bacteria. Here high frequency monitoring using sensors were deployed in two catchments to show how the daily flux of dissolved organic carbon is respired away by bacteria over an annual cycle. A whole ecosystem experiment tested the effects of labile organic carbon addition on carbon cycling, C:N:P stoichiometry, biotic CO2 emission, trophic transfer efficiencies. Isotopic probing allowed to trace the added carbon through the food web and quantify the reciprocal carbon subsidies between primary producers and bacteria. Part of the carbon derived from natural allochthonous organic matter can feed the autotrophs via the CO2 produced by stream bacterial respiration, intermingling the green and brown webs. The interaction between autotrophs and bacteria shifted from mutualism to competition with carbon addition under nutrient limitation (N, P) increasing biotic CO2 emissions. Without nutrient limitation, mutualism could be reinforced by a positive feedback loop, preventing further biotic CO2 emissions.
- Biogeochemistry
- Food Webs
- Metabolism
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Presenters/Authors
Benoit Demars
(), Norwegian institute for water research (NIVA), benoit.demars@outlook.com;
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Nikolai Friberg
(), Norwegian Institute for Water ResearchNorwegian Institute for Water Research (NIVA), Oslo, Norway , Nikolai.Friberg@niva.no;
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Barry Thornton
(), The James Hutton Institute, barry.thornton@hutton.ac.uk;
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