Impacts of low oxygen on Puget Sound aquatic life (infographic)

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.

Infographic describing impacts of low oxygen on Puget Sound aquatic life
Impacts of low oxygen on Puget Sound aquatic life

Download the infographic (pdf)

Text alternative for web accessibility

How does low oxygen impact aquatic species?

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.

The most extreme impacts of low oxygen to aquatic organisms include decreased ability to reproduce, slowed development, deformities, and death. For some species, including squid, crabs, and octopuses it can impair eyesight.

How do species respond?

Physiological changes can help some species survive but may come at a cost. Some fish, for example, can increase the surface area of their gills to allow more water (and thus more oxygen) to pass through. But this can increase the amount of pollution absorbed by their bodies. Other animals can increase their blood circulation or modify their need for energy.

Mobility is a big advantage. Many species can move away to escape low oxygen conditions unless they are stationary like mollusks or anemones. Some species can temporarily acclimate, and others have adapted over generations to tolerate low oxygen. In more extreme cases, species can die, especially if the change in oxygen is sudden or they are exposed for too long.

Did you know?

Dungeness crab larvae are more sensitive to low oxygen than adult crabs. Exposure to lethal levels of low oxygen at the larval stage could imperil future crab populations.

When it comes to oxygen, climate change strikes a double blow for aquatic life

Warmer water provides less oxygen at the same time, it increases an animal’s need for it.

Aquatic species may escape, acclimate, adapt, or die with exposure to low oxygen

TOLERATE - Some bottom-dwelling, immobile species, like mussels, may be able to tolerate longer periods of low oxygen.

DIE - Sensitive, immobile species like geoduck clams may die with exposure to low oxygen. The species doesn't inhabit places where oxygen is naturally low, even periodically.

ESCAPE - Species like Pacific herring that live closer to the surface can swim way from low-oxygen areas and are less likely to be exposed to deep-water low oxygen. Mobile species like Dungeness crab and octopuses can move elsewhere but increased movement requires more oxygen and new locations may expose them to other stressors and predators.

ACCLIMATE - At the risk of impairing growth and reproduction, some species including cephalopods (e.g. squid) can acclimate by temporarily reducing their oxygen demand.

ADAPT - Over generations, some species including sablefish (black cod) have adapted to naturally low oxgygen.

Dissolved oxygen typically decreases with depth.

Sources

Marine Water Quality, EPA 2021
McCormick et al. 2019
Seibel 2016

Check out other infographics in this series: