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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.

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

A purple sea star attached to a rock covered with mussels and seaweed.

Oxygen for life: How low dissolved oxygen affects species in Puget Sound

Scientists are reporting a decline in oxygen-rich waters throughout the world. Causes for the decline vary from place to place but may involve climate change and increasing discharges of tainted water. In Puget Sound, low oxygen levels can occur naturally or due to eutrophication from human-caused pollution. In this five-part series, we describe the critical nature of oxygen to Puget Sound sea

A person holding a rope attached to a wire cage holding recently captured Dungeness crabs.

How crabs respond to low oxygen in Hood Canal

As observed in Hood Canal, low-oxygen conditions can upend the lives of Dungeness crabs trying to stay alive. Levels of dissolved oxygen can alter predator-prey relationships for a multitude of species, affecting populations throughout the food web. Part two of our series "Oxygen for life" examines a crab case study.

View from underwater of bubbles rising to the surface of the ocean with sunlight above.

Warmer waters will mean less oxygen for species

In time, lower dissolved oxygen worsened by climate change could increase the abundance of rare species in Puget Sound while putting populations of more common species into a tailspin. Part three of our series "Oxygen for life" looks at how warmer waters will gradually make it harder for many sea creatures to breathe. 

J27, a 32-year-old male orca named Blackberry, cruises off the Seattle waterfront in October 2012. Blackberry’s community, the endangered Southern Resident killer whales, are impaired by a high rate of inbreeding. Photo: National Marine Fisheries Service, taken under permit #16163

Inbreeding hinders population recovery among endangered Southern Resident killer whales

While a scarcity of Chinook salmon and other environmental factors may be pushing the Southern Resident killer whales toward extinction, a new genetics study has revealed that inbreeding has been exerting a powerful, overriding influence upon the small, genetically isolated population.

Rhinoceros auklet carrying sand lance. Photo by Peter Hodum.

Resilience to a severe marine heat wave at two Pacific seabird colonies (author summary)

A 2023 paper in the journal Marine Ecology Progress Series examines seabird reproductive and dietary response to a severe marine heat wave affecting the California Current ecosystem from 2014 to 2016. The study involved rhinoceros auklet colonies on Destruction Island (California Current) and Protection Island (Salish Sea). The paper's first author Eric Wagner describes some of the findings from

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Puget Sound Marine Waters 2021 Overview

Each year, the Puget Sound Ecosystem Monitoring Program (PSEMP) releases a Puget Sound Marine Waters Overview, a report combining a wealth of data from numerous comprehensive environmental monitoring programs. The latest report provides an overview of marine conditions in 2021 and represents the collective effort of 76 contributors from federal, tribal, state, and local agencies, academia

A cougar swimming with its head above calm, glassy water.

A cat gets its feet wet

Biologists are intrigued by the prospect of island-hopping cougars in the Salish Sea. Could swimming ability lead to improved genetic diversity among the big cats?

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Eyes Over Puget Sound: A Decade in Review

The Washington State Department of Ecology has reached one hundred Eyes Over Puget Sound reports. Since 2011, Ecology has provided aerial observations and documented visible features at the surface of Puget Sound from a floatplane. This unique perspective from the air featured Puget Sound's natural beauty, its oceanographic complexity, and its ecological treasures. It also raised awareness of the

A man on a boat looking through a camera with a large lens.

Remembering Ken Balcomb and his extraordinary life with killer whales

Environmental reporter Christopher Dunagan remembers the life and influence of pioneering orca researcher Ken Balcomb.