Episodic Hypoxia in the Western Basin of Lake Erie

Session: 45. - Hypoxia: Causes, Impacts, and Management

Aidin Jabbari, University of Guelph, [email protected]
Leon Boegman, QUEENS UNIVERSITY, [email protected]
Yingming Zhao, Ontario Ministry of Natural Resources, [email protected]
Josef Ackerman, University of Guelph, [email protected]

Abstract

Hypoxic and anoxic conditions have been observed almost annually in the western basin of Lake Erie where there is concern for the quality of fish habitat. We investigated the dynamics and causes of hypoxia using field measurements at two locations in Pigeon Bay for a 30-day period in late summer 2017. We obtained dissolved oxygen (DO) and temperature profiles within 3 m of the surface and 1 m above the bed, as well as near bottom velocity. Although the bottom flow was dominated by the eastward river flow and the ~14 hr surface gravitational seiche, we recorded two hypoxic events (DO <2 mg/L) within 0.5m of the bed caused by upwelling of water from the central basin. Vertical flux of DO shows a diurnal pattern caused by diurnal stratification and is maxim during the stratified period between upwelling events, due to a strong DO gradient through the thermocline. A third event characterized by continuous decline in DO from 8.3 to 4.9 mg/L within 1 m above the bed was associated with episodic stratification during a calm period near the end of the deployment. Results will inform modeling efforts for the prediction of hypoxia as well as fisheries management.

1. Keyword
Lake Erie

2. Keyword
oxygen

3. Keyword
hydrodynamics

4. Additional Keyword
hypoxia

5. Additional Keyword
stratification

6. Additional Keyword
upwelling