2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/24/2021 | 8:30 AM - 10:30 AM | CONTRIBUTION OF INTERNAL METABOLISM TO THE CO2 EVASION OF A STREAM IN THE WET-DRY TROPICS OF AUSTRALIA | Virtual Platform

CONTRIBUTION OF INTERNAL METABOLISM TO THE CO2 EVASION OF A STREAM IN THE WET-DRY TROPICS OF AUSTRALIA

While evasion represents the largest flux of carbon (C) from tropical streams, estimates are subject to large uncertainties and the source of evading C is often unknown. To estimate the potential contribution of internal metabolism to CO2 evasion, we monitored O2 and CO2 in a headwater stream of the Australian wet-dry tropics. Dissolved gas concentrations were measured at two sites along the stream, one riffle and one pool. Net stream metabolism was obtained via the one-station technique, while five methods were used to estimate the gas transfer velocity (k) and CO2 evasion: (1) floating chambers, (2) mass balance, (3) Bayesian multiday model, (4) night-time regression and (5) empirical equations based on hydraulics. Our results show that both reaches are highly heterotrophic, with respiration an order of magnitude higher than gross primary productivity. Respiration is higher at the pool while k and CO2 evasion are higher at the riffle. Direct methods (1, 2) are reliable and show similar results. Indirect methods (3, 4, 5), however, show large disparities and are unable to predict k under low water level conditions. Respiration can contribute up to 50% of evading C.

Tropical
Tropical streams and lakes
Biogeochemistry

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Presenters/Authors

Vanessa Solano (), Research Institute for the Environment andLivelihoods, Charles Darwin University, vanessa.solano@cdu.edu.au;