Hypoxia

About 83% of the water in Puget Sound comes from the ocean. That brings with it all kinds of benefits, including an ocean-size amount of life-giving nutrients that feed the creatures that live here. But it has one potential drawback. That ocean water is notoriously low in oxygen. Why is that and what does it mean for the future of Puget Sound?

A new study outlines the strong link between dissolved oxygen declines and increasing water temperatures, raising questions about the effect of future climate change on Puget Sound.

There is an ongoing concern that human activities can cause reductions in the amount of oxygen available to fish and other marine species. In Puget Sound, scientists are working to evaluate when and where some of these reductions could have an adverse ecological impact. As part of a series of workshops on Puget Sound water quality, the Puget Sound Institute asked Dr. Tim Essington of the University of Washington School of Aquatic and Fishery Sciences to describe how low dissolved oxygen affects species like salmon or Dungeness crabs. The following text is adapted from a video presentation by Essington in 2023.

Low dissolved oxygen levels put aquatic life in Puget Sound at risk – but not everywhere. A combination of careful monitoring efforts and powerful computer models are now enabling scientists to identify which areas of our regional waters are most prone to low oxygen levels, when, and why. This article is part of a series of reports funded by King County about the quest to define healthy oxygen levels in Puget Sound.

Oxygen is indisputably essential to aquatic life, but conflicts are brewing over water quality standards mandated in state regulations. This article is part of a series of reports funded by King County about the quest to define healthy oxygen levels in Puget Sound. By some estimates, those definitions could affect billions of dollars in state and local spending. [Editor's note: King County is currently in litigation with the Washington State Department of Ecology over the issue of dissolved oxygen water quality standards.]

Chronic stress from lack of oxygen can make aquatic organisms more vulnerable to disease, pollution, or predation. Low oxygen can also result in reduced habitat for some species. Aquatic species may escape, acclimate, adapt, or die with exposure.