Hypoxia

In some cases, vast stretches of open water become hypoxic, or low in oxygen. Unable to sustain life, these areas, called dead zones, may cause die-offs of fish, shellfish, corals, and aquatic plants.

Sources:

NOAA

Additional resources:

Hood Canal Dissolved Oxygen Program

Independent review of human impacts on dissolved oxygen in Hood Canal

 

Overview

When are waters considered hypoxic?

The search goes on for a set of definitions and thresholds to represent low-oxygen concentrations that threaten various aquatic creatures. Over the years, ecologists have relocated, reshaped and revised the word “hypoxia” to describe these conditions. In part four of our series "Oxygen for life" we look at how scientists determine whether oxygen levels are low enough to be considered harmful to sea life. 

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A crab pot (circular mesh cage) with an oxygen sensor (a white tube inside the cage) is held off the side of a boat as it is about to be dropped into the water.

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