Articles | Volume 20, issue 4
https://doi.org/10.5194/bg-20-839-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-20-839-2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
24 Feb 2023
Research article |
| 24 Feb 2023
| 24 Feb 2023
Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system
Mathilde Jutras
CORRESPONDING AUTHOR
Department of Earth and Planetary Sciences, McGill University, 3450
University Street, Montreal, QC, H3A OE8, Canada
Université Laval, 1045 av. de la Médecine, Québec, QC, G1V 0A6, Canada
Alfonso Mucci
Department of Earth and Planetary Sciences, McGill University, 3450
University Street, Montreal, QC, H3A OE8, Canada
Université du Québec à Montréal, 201 av. du Président-Kennedy, Montréal, QC, H2X 3Y7, Canada
Gwenaëlle Chaillou
Institut des Sciences de la Mer de Rimouski (ISMER) – Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC, G5L 3A1, Canada
Université Laval, 1045 av. de la Médecine, Québec, QC, G1V 0A6, Canada
William A. Nesbitt
Department of Oceanography, Dalhousie University, Steele Ocean
Sciences Building, 1355 Oxford St., P.O. Box 15000, Halifax, NS, B3H
4R2, Canada
Douglas W. R. Wallace
Department of Oceanography, Dalhousie University, Steele Ocean
Sciences Building, 1355 Oxford St., P.O. Box 15000, Halifax, NS, B3H
4R2, Canada
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Short summary
The deep waters of the lower St Lawrence Estuary and gulf have, in the last decades, experienced a strong decline in their oxygen concentration. Below 65 µmol L-1, the waters are said to be hypoxic, with dire consequences for marine life. We show that the extent of the hypoxic zone shows a seven-fold increase in the last 20 years, reaching 9400 km2 in 2021. After a stable period at ~ 65 µmol L⁻¹ from 1984 to 2019, the oxygen level also suddenly decreased to ~ 35 µmol L-1 in 2020.
The deep waters of the lower St Lawrence Estuary and gulf have, in the last decades, experienced...
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