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Biogeochemical Controls on Coastal Hypoxia.
Katja Fennel1, Jeremy M Testa2
1Department of Oceanography, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada;
Annual Review of Marine Science
|June 12, 2018
Summary
Coastal aquatic systems face low-oxygen conditions, termed hypoxia. This review synthesizes factors controlling hypoxia across diverse environments, offering a framework for understanding and predicting future changes in these vital ecosystems.
Area of Science:
- Marine Biology
- Oceanography
- Environmental Science
Background:
- Aquatic environments exhibit low-oxygen conditions, including hypoxic, suboxic, anoxic zones, and oxygen minimum zones.
- These phenomena are sometimes inaccurately referred to as "dead zones" in popular media.
Purpose of the Study:
- To elucidate factors underlying oxygen depletion in diverse coastal systems.
- To synthesize general relationships between hypoxia and its controlling factors.
- To provide a framework for discussing future changes in coastal oxygen levels.
Main Methods:
- Review of system-specific characteristics for estuaries, river-dominated shelves, and upwelling regions.
- Analysis of first-order processes contributing to oxygen depletion.
- Proposal of a nondimensional number for cross-system comparison of hypoxia and residence times.
Main Results:
- Identified key processes driving hypoxia in coastal systems.
- Synthesized relationships between hypoxia and controlling factors across different environments.
- Demonstrated the utility of a nondimensional number for comparing hypoxia dynamics.
Conclusions:
- Hypoxia generation in coastal systems follows basic underlying principles.
- The proposed framework aids in understanding and discussing future changes in coastal hypoxia.
- Recognizing anthropogenic nutrient loads is crucial for managing estuarine hypoxia.
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