Keywords: Climate change, Species and food webs, Algae, Marine habitat, Kelp, Salish Sea, Implementation Strategies, Food web, Rockfish, Monitoring, Tribes

They rival tropical forests in their richness and diversity, but Puget Sound's kelp beds have declined steeply in recent decades. Scientists are just starting to understand the extent of these losses through mapping projects and consultations with local tribes. What they are finding is bringing kelp to the forefront of Puget Sound's environmental concerns.


One day in 2017, Toby McLeod spread out a nautical chart at his father’s house. The chart depicted the traditional territory of the Samish people in the San Juan Islands. McLeod, a Samish tribal member and field technician with the tribe’s Department of Natural Resources, wanted his father’s help mapping the historic location of bull kelp beds around the islands.

McLeod’s father has been fishing commercially for salmon, crab, shrimp, and dogfish since the late 1950s. And fishers know where kelp is. The plant – technically a type of brown algae – grows in shallow water on rocky substrate, so its presence indicates a navigation hazard. Get too close to kelp and it can also foul a boat’s prop, requiring a dip in unpleasantly chilly water to free your vessel. But at the same time, the edges of kelp beds are often prime fishing spots.

As luck would have it, McLeod’s uncle, who had also worked as a commercial fisher, happened to be visiting that day. Between them, the two men had almost a century’s worth of fishing experience. McLeod listened as they debated back and forth and drew on the map areas of agreement. “I was using them to kind of balance each other and come up with as clear a story as I could,” he says.

The result was a portrait of kelp both familiar – such as the beds that fringe the western side of San Juan Island – and vanished: The men remembered a kelp forest filling a portion of Bellingham Channel, for example, that there’s no trace of today.  

The farther you get away from the open ocean – closer to human impacts and farther away from oceanic water – those are the areas where we’re most concerned about kelp losses.

Helen Berry, Washington Department of Natural Resources

The map is also emblematic of a variety of recent studies, using diverse methods, that have documented kelp decline and disappearance in many parts of Puget Sound. It’s a local story with links to global concerns, as kelp habitats off the coasts of California, Australia, and Tasmania have all experienced severe declines in recent years.

“Luckily, we still have areas where [bull kelp] occurs” in Puget Sound, says Helen Berry, manager of the Nearshore Habitat Program at the Washington Department of Natural Resources. “But we really need to focus on figuring out what's going on, what the main stressors are, and what we can do about it.”

Canopy cover

Bull kelp (Nereocystis luetkeana) is one of 23 species of kelp found in Puget Sound. It’s the largest species and the only one capable of forming a surface canopy that occurs in inland waters. Dense stands of canopy-forming kelp are known as kelp beds or, if they are particularly large, kelp forests.

Kelp beds in San Juan Channel. Photo: Thomas Mumford

Kelp beds in San Juan Channel. Photo: Thomas Mumford

“Kelp is awesome for the same reasons that coral reefs and eelgrass and mangrove forests are awesome,” says Max Calloway, a biologist working on kelp projects with the nonprofit Puget Sound Restoration Fund (PSRF). That is, it’s an enormously productive habitat teeming with life.

Kelp forests can rival tropical rainforests in primary productivity, meaning the amount of the sun’s energy transformed into living organisms in a given amount of time. Kelp freely shares the energy it captures through photosynthesis, constantly releasing dissolved sugar and sloughing bits of tissue into the water, providing a foundation for the food web near the shoreline. Studies suggest that between one-third and two-thirds of carbon in the bodies of rockfish in the North Pacific may ultimately be derived from kelp.

This abundance of food and places for hiding and hunting draws a host of species to kelp beds. “You look down and a Chinook salmon swims by, there's forage fish in hiding among the leaves of the kelp,” says Alan Clark, a Sequim resident who is part of a citizen-science project to monitor kelp beds in the Strait of Juan de Fuca by kayak. Other species that can be spotted in and near kelp beds include river and sea otters, harbor seals, sea lions, and southern resident orcas.

A harbor seal hunts for prey in kelp forests. Photo: Florian Graner

A harbor seal hunts for prey in kelp forests. Photo: Florian Graner (CC BY 2.0)

“You really get an idea of just the sheer number of species that are in some way dependent on our kelp beds,” Clark says. “This is a vital spot for all kinds of animals in our region.”

So far, however, kelp has received less attention by conservationists than other species and habitats such as eelgrass, which is listed as a ‘Vital Sign’ of Puget Sound health by the state’s Puget Sound Partnership. One reason may be that kelp is harder to study. Bull kelp is an annual plant, growing anew from a microscopic beginning each spring, and being washed away by storms in the autumn. Plus, kelp was thought to be more resilient than other types of nearshore vegetation.

Emerging concerns 

Over the last decade, that view has changed. In 2010, three species of rockfish found in Puget Sound were listed as threatened or endangered; all three are found in kelp beds and one of them, bocaccio, is especially dependent on kelp as rearing habitat. The listing highlighted gaps in kelp knowledge. “In general, there’s not very good data – precise spatial data – about the location and species assemblages of kelp in Puget Sound,” says Dan Tonnes, a NOAA Fisheries biologist working on rockfish.

And concern was bubbling up from other places as well. Anglers wondered where bull kelp beds had gone. Samish tribal members told their Department of Natural Resources staff that they were having trouble finding kelp to wrap salmon in as part of a traditional way of preparing the fish. Scientists noticed kelp beds they’d long known as reliable landmarks shrinking or disappearing altogether. And so it went around the Sound.

The first task was to get a handle on where exactly kelp beds were located, how big they were, and how they have changed over time. For this, Samish Department of Natural resources scientists turned to aerial photography. They used a computer GIS program to outline the location of kelp beds on high-resolution aerial photographs of the San Juan Islands taken in 2016.

The unique shape and distinctive green shade of kelp plants is easy to recognize in the photographs, says Casey Palmer-McGee, a GIS specialist with the tribe. But digitizing the photographs still took two months of painstaking work – “click, click, click, click, click,” he says, mimicking the repetitive computer mouse motions involved in tracing each bed.

The team compared their data with those from a 2006 study of the same area that also used aerial photography. This showed a loss of 305 acres, or roughly 36% of all bull kelp in the San Juan Islands, over the course of a decade.

At first, it wasn’t clear that there was a big problem: Kelp beds can vary by up to 30% from one year to another. But as the researchers looked closer, a more alarming picture emerged. On average, each island had lost half its kelp area. And some had experienced even more devastating losses: Kelp had declined by 62% around Shaw Island, 72% around Blakely Island, and 77% around Patos Island.

The map of tribal elder knowledge that McLeod worked on adds another dimension to the findings. “We think that loss has been going on for quite a bit longer” than a decade, says Samish DNR head Todd Woodard.

Shrinking boundaries

Aerial photographs aren’t available for all of Puget Sound’s shorelines, so the Northwest Straits Commission developed a protocol for measuring the size of kelp beds by kayaking around the perimeter with a GPS device. Individual county Marine Resources Committees then recruited citizen-scientist volunteers to survey a handful of kelp beds in each jurisdiction.

“It's a nice way to go out and paddle around, get to know your local waters close up, and you have a purpose,” says Linda Rhodes, a microbiologist with NOAA who lives on Whidbey Island and coordinates the kayak survey program in Island County.

Participants survey each bed once a month, usually from June through September, and take photographs and record water temperature and depth as they kayak the perimeter of the bed. Dana Oster, the Northwest Straits Commission’s marine program manager, estimates that roughly 70 volunteers kayaked more than 770 miles between 2015 and 2018. In summer 2019, the program was active in six counties – Clallam, Island, Jefferson, Skagit, Snohomish, and Whatcom.

Snohomish County has emerged as an area of particular concern, Oster adds. Beds near Mukilteo and Meadowdale have shrunk to the point of no longer having a perimeter to kayak around – now, they’re just scattered clumps of kelp.

These are the southernmost of the roughly 25 to 30 beds being tracked in the program. Farther South in Puget Sound, kelp is in even worse shape, as state DNR researchers have established.

Berry led a team that surveyed four South Sound kelp beds in 2013, 2017, and 2018. All four beds – at Squaxin Island, Brisco Point, Devil’s Head, and Fox Island – declined significantly over that time, according to their report released earlier this year. The Brisco Point and Devil’s Head beds were absent altogether by 2018.

“The farther you get away from the open ocean – closer to human impacts and farther away from oceanic water – those are the areas where we’re most concerned about kelp losses,” Berry says.

Pilot experiment

For a few weeks in the summer of 2019, full-grown bull kelp plants waved languidly at the surface of the water in Smith Cove near Seattle. This small and unlikely kelp bed – buffeted by the wakes of huge cruise ships, with the Space Needle as its backdrop – was the result of a pilot experiment in kelp restoration carried out by PSRF.

Months earlier, PSRF divers had attached lengths of twine, coated with a brown fuzz formed by millions of millimeter-long young kelp plants, to concrete anchors they had placed on the sea floor. Calloway jokingly likens the process to “underwater basket weaving.”

VC pipes wrapped in twine inoculated with kelp spores support young kelp plants (juvenile sporophtyes) that will be outplanted in the ocean. Photo: Max Calloway/PSRF

PVC pipes wrapped in twine inoculated with kelp spores support young kelp plants (juvenile sporophtyes) that will be outplanted in the ocean. Photo: Max Calloway/PSRF

More broadly, kelp restoration isn’t all that different from forest restoration on land, although kelp has a more complicated and less well understood life cycle than a tree does. That life cycle includes two distinct phases, known as the gametophyte and the sporophyte. Kelp beds are formed by mature sporophytes. Kelp overwinters as either gametophytes, which are microscopic and may be able to persist in the environment for multiple years, tiny sporophytes, or a mix of both.

The first task when PSRF began working on kelp restoration several years ago was to figure out which life stage to outplant, and at what time of year. A series of field experiments suggested the best approach would be to set out immature sporophytes in late winter, just as the days begin to lengthen and daytime low tides return. This gives the young plants enough light to get established, early enough to avoid getting swamped by other aquatic vegetation.

The kelp planted at Smith Cove didn’t stick around for very long, but it was still proof of principle that the method could result in a mature kelp bed. In 2020 PSRF plans to carry out a larger kelp restoration project at Jefferson Head off the Kitsap Peninsula, the site of a former kelp bed that has disappeared in recent years.

The next question is whether restoration efforts can produce a kelp bed that comes back for a second year. “Our ultimate goal is to figure out the most cost-effective way to go out and do one planting in an area that will then restart that natural process and get you a naturally persistent kelp bed,” Calloway says.

Diving deeper

To answer that question, and to halt and reverse kelp loss more broadly, scientists will likely need to know more about the factors that are causing kelp to disappear in the first place, and what life stages are most affected. For now, researchers have a lot of hypotheses, but few clear causal links.

It could be that increased sedimentation is smothering young kelp plants or covering up the bedrock and cobbles that they need to attach to. Excess nutrients in agricultural and urban runoff could be enabling other species like turf-forming algae to outcompete kelp. Competition with the invasive alga Sargassum muticum may also be a factor.

Researchers have observed large numbers of kelp crabs feeding on kelp in struggling South Sound beds. Could there be an overabundance of these herbivores, perhaps due to a lack of their own predators, such as rockfish?

Other evidence implicates water temperature. Kelps are cold-water organisms, and bull kelp does best in water between about 5 and 17 °C. Historical data suggest that Salish Sea kelp beds track climatic fluctuations such as El Niño events. Now, increasing average water temperatures, stronger El Niños, and marine heat waves such as “the Blob” may be pushing kelp into the danger zone more often – a problem that is only likely to get worse as climate change intensifies.

“If that is the problem, it’s going to be a hard one to fix at a local level,” says Tom Mumford, a retired state DNR kelp biologist. “The solution is not going to be a Washington solution,” he says, “it’s going to be a global solution.”Various agencies, tribes, and nonprofit groups are strategizing about how to investigate these hypotheses. For example, the Samish DNR will use an ROV to gather clues about stressors that might be affecting local kelp beds next summer.

Maiden of Deception Pass story pole carved by carved by Tracy Powell. Photo: Cody Logan (CC BY-NC-SA 2.0)

The Maiden of Deception Pass carved by Tracy Powell tells the story of Qw'elqw'o7lewut [pronounced phonetically as Ko-Kwal-alwoot], a Samish woman who goes to live underwater to save her people from starvation. Photo: Cody Logan (CC BY-NC-SA 2.0)

Their high-tech plan has a resonance with traditional teachings. The Samish and other Coast Salish tribes have a story about a woman who marries a man from beneath the sea. She comes back to visit her home village once a year, but as the years go by, the woman becomes more and more a being of the sea. Barnacles grow on her skin, her hair is transformed into kelp, and she seems increasingly unhappy on land. Eventually, her family releases her from her obligation to return. She stays underwater, her presence there ensuring that the people will always have abundant seafood and clean water.

In English, the woman is usually referred to as the Maiden of Deception Pass. But her Samish name, Qw'elqw'o7lewut (Ko-Kwal-Alwoot), best translates as “lots of kelp attire.” To the Samish, the story emphasizes the importance of taking care of the environment so that it may take care of the people.

“Whether you look at it from an Indigenous perspective or a modern ecological perspective, kelp is a critical habitat for a lot of other species,” McLeod says. Not the least of which is us.


About the author: Sarah DeWeerdt is a Seattle-based freelance science writer specializing in biology, medicine, and the environment. Her work has appeared in publications including Nature, Conservation, and Nautilus.