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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.

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. 


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

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 life. Scientists are finding that changes in oxygen levels can lead to physiological adjustments, shifts in predator-prey relationships and other repercussions throughout the food web.


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

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.

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

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.

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 the study in this informal summary.


Report cover

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, nonprofits, and private and volunteer groups. 


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

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?


Report cover

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 challenges that the water body is facing today. Our image-rich documentation of known eutrophication indicators ranges from algal and Noctiluca blooms to macroalgae, jellyfish, and human stressors. It provides a visually captivating time-capsule of issues facing Puget Sound. The report is rich in educational and outreach material, inspired numerous news reports, and drew academic and public attention during the period of marine heat wave of the north Pacific, The Blob.


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

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


Eyes Over Puget Sound report cover

The report comes after a third year of La Nina conditions. Weak upwelling off the coast and low river flows of major rivers meant less cold, nutrient-rich, upwelled water was being entrained into Puget Sound in late summer and fall. Water conditions in Puget Sound in October were generally expected while Willapa Bay and Grays Harbor were both unusually warm and salty. Smoky air restricted our flight to Southern Puget and Central Sound where we saw blooms in terminal bays as well as patches of jellyfish. Sediment in Commencement Bay and along shorelines in Totten Inlet was unusual for a dry fall. A healthy foodweb has at its base a balance of nutrients. Explore what we found over the period of two decades of monitoring.


View of Puget Sound with red-orange water near the shoreline and blue sky with clouds above land in the distant background.

How do excess nutrients trigger low oxygen conditions in Puget Sound and what do those conditions mean for the species that live here?


Microscopic view of diatoms in various shapes and sizes.

Diverse communities of microscopic organisms called phytoplankton make up the base of the aquatic food web. In that role, they are essential to the tiny animals that eat them, but phytoplankton are not dependent on others. Thanks to chlorophyl, these tiny organisms can generate their own energy from nutrients and sunlight. Despite their critical importance to a great diversity of sea life in Puget Sound, phytoplankton can also contribute to low-oxygen conditions, and some can be harmful in other ways.


View of turbulent ocean water with rain clouds on the horizon and land to the north and south

In a new series we are calling Ask a Scientist we interview local researchers to get their thoughts on some of the important but lesser-known scientific facts about the Puget Sound ecosystem. Today, we speak with University of Washington oceanographer Parker MacCready about Puget Sound’s “underwater Amazon” and why it has profound implications for Puget Sound science and policy. It all begins, he says, with the mixing of fresh and salt water and something called the estuarine exchange flow.


Neotrypaea californiensis, the bay ghost shrimp. Image courtesy of Dave Cowles (wallawalla.edu)

Fall’s chill is in the air (finally!), leaves are turning colors, and skeletons and spider webs are popping up in yards all over town. Meanwhile, under the mud of Puget Sound, there’s a strange critter that stays in its ethereal costume all year long – the burrowing ghost shrimp.


A single sea bird floating on the water with several thin silvery fish in its beak.

Where do Protection Island's rhinoceros auklets go to find their food? Scientists hope GPS tags will offer new insight into the bird's still mysterious foraging behavior. Biologist and science writer Eric Wagner reports from the field. 


Report cover

On August 4, 2022, the Environmental Protection Agency (EPA) approved the 2022-2026 Action Agenda adopted by the Leadership Council as the Puget Sound National Estuary Program's (NEP) Comprehensive Conservation and Management Plan. 


Conference logo

The 2022 Salish Sea Ecosystem Conference took place April 26th to April 28th in an online format. All 2022 presentations from the conference will be available publicly on the SSEC repository site, Western CEDAR, unless an embargo was placed by the author/s.


View of river looking upstream with water flowing through large pieces of wood in the foreground and two people walking in the stream in the background.

A new report says further study may reveal why experts cannot find expected benefits to salmon populations, despite widespread use of wood in stream restorations.


A downy black seabird chick nestled in the corner of a wooden box that is resting on top  of gravel.

Biologist and science writer Eric Wagner recently returned from a trip to observe pigeon guillemots on Protection Island. He wonders: How much do we really know about the health of seemingly abundant bird populations?


A single harbor seal swimming with its face above and body below the surface of the water.

Occasionally, our magazine includes reports and essays from guest writers on the subject of Puget Sound ecosystem recovery. Biologist and author Eric Wagner has this look at an ongoing harbor seal survey at the mouth of the Stillaguamish River. Wagner says the study hinges on a basic question: Who is eating the salmon? 


Shoreline composed of a human-made rock wall next to water with a small boat tied to the shore.

The Swinomish Indian Tribal Community has begun constructing the first known clam garden to be built in modern times. They hope that what was once an ancient way of cultivating shellfish can now be a hedge against climate change.


: Underwater view of a person in scuba diving gear holding a clipboard and grasping a stalk of brown kelp.

Puget Sound Restoration Fund has launched a network to track declining kelp populations in the Salish Sea. The three-year initiative aims to support and standardize underwater monitoring to improve kelp conservation in the region.


A single grey bird with a dark eye standing in flowing water of a river.

Dam removals are often associated with salmon recovery, but new research on the Elwha River suggests that birds also benefit. Scientists say birds are a sometimes-overlooked indicator of river health.


DFO photo of orca J35 known as Tahlequah pushing her calf on Aug. 8, 2018, off Cape Flattery, Wash. Photo by Sara Tavares, Fisheries and Oceans Canada. Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0)

It has been four summers since a mother orca’s dramatic vigil brought worldwide attention to the plight of Puget Sound’s southern resident killer whales. A recent gathering of legal experts, conservationists, and academic scholars looked at how perceptions of the whales have changed since then and whether laws and policies should reflect new thinking about ethical responsibilities to orcas and other animals.