Kelp forests once grew thick here, but have been grazed down by growing populations of sea urchins, in this image from 2020. According to a status report released by the Oregon Kelp Alliance in November, nearly 900 acres of bull kelp forest has essentially disappeared off the Oregon Coast since 2010.
Oregon State University
A new report spells out exactly how much Oregon’s kelp forests have dwindled over the past decade or so — and the picture is bleak.
According to a status report released by the Oregon Kelp Alliance in November, nearly 900 acres of bull kelp forest has essentially disappeared off the Oregon Coast since 2010. Only around one-third of Oregon’s kelp forests remain — important oases facing ongoing threats and stressors in a changing ocean.
For the past two years, the Oregon Kelp Alliance has been developing a tool kit to aid in the recovery of the kelp forests, piloting various approaches and techniques without a clear sense of what could work for the Oregon Coast.
Now, with their new report forming a foundation and federal funding in hand, they hope to build on that early work and move forward on a plan over the next two years to restore this diminished — and diminishing — ecosystem.
“We have things that we understand well and that we need to start moving on,” said Sara Hamilton, science coordinator for the Oregon Kelp Alliance. “And we have things that still need more research and development … but we’re not going to be able to wait until we have a perfect understanding of this system before we start acting.”
Key questions
Even with a better sense of the tools they need to use and the landscape they are working in, key questions remain.
In their report, the Oregon Kelp Alliance includes a list of critical areas of future investigation. On the list are questions like: How do temperature changes and marine heat waves impact kelp forests? What sites along the Oregon Coast are most desirable for restoration work? Or protection? What criteria should be used to make those decisions?
There is a need, the report says, for more environmental monitoring to better understand how forces like climate change are impacting the forests.
Overall, the decline of kelp forests remains understudied and not well understood off Oregon while the condition of the kelp forests themselves varies widely.
There is little data for the kelp from the 1800s through the 1980s except for statewide surveys in 1911 and 1954, looking at the extent of bull kelp. In the 1980s and ’90s, satellite imagery became available that has provided additional information about the historic distribution of kelp — the waving fronds at the top of bull kelp extend to the ocean surface and can be seen from space.
The Oregon Department of Fish and Wildlife surveyed the forests throughout the ’90s when there was interest in commercial harvest of kelp. The state ultimately banned the commercial harvest of bull kelp over concerns about how much the biomass of kelp could shift from year to year. Bull kelp is listed as a priority species in Oregon’s Conservation Strategy.
The Department of Fish and Wildlife did additional surveys in 2010 and 2022. Scott Marion, a marine habitat project leader with the state, led recent state survey efforts and told KMUN he expects there will be a stronger focus on the kelp beds now and — likely — more regular monitoring going forward.
Kelp forests are a key marine ecosystem. They act as a home and nursery for a number of fish species important in Oregon’s commercial and recreational fisheries. Commercial urchin divers were among the first to start raising the alarm about the forests in recent years.
“We had these anecdotal accounts that there was loss, but we didn’t really have a statewide understanding of how extensive that was,” Hamilton said.
When the Oregon Kelp Alliance went out to collect data and statistics to try to determine the extent of the problem, they found “exactly what community members have been saying, which is really extensive loss,” Hamilton said.
When it comes to wrapping their heads around the issue, however, Hamilton and Marion say there are several challenges.
First, there is the fact that kelp is mostly an annual species.
In recent surveys and in looking at older surveys, Marion charted how the kelp beds were both contracting and moving into other areas.
“We’re not looking at a situation where the kelp contracts to some kind of minimal core,” Marion said. “It’s moving around. It’s recruiting to new locations. It’s a very dynamic resource.”
Tom Calvanese, the head of the Oregon Kelp Alliance and field station manager for Oregon State University’s Port Orford Field Station, says that when they’re thinking about replanting kelp or clearing areas for kelp, they need to keep in mind the “lag effect” of an annual species
“Like, what happens this year is a function of what happened last year,” he said.
Urchins
A close-up of a purple sea urchin.
Stephani Gordon / OPB
One of the biggest drivers in bull kelp loss appears to be a boom in purple sea urchin populations. The urchins multiplied around the time a mysterious disease decimated sea star populations, in particular sunflower sea stars, voracious predators of urchins.
Purple urchins graze on kelp and can enter long dormant states when all the kelp is gone, biding their time until there is food again. This can make it tricky to reestablish kelp where “urchin barrens” — areas where there is nothing but urchins visible as far as a diver can see — have taken over.
Over the last two years, one program the Oregon Kelp Alliance piloted is to send down divers with hammers to smash purple urchins and clear out areas for kelp to return. The group has also collaborated on experiments with developing a potential commercial market for purple sea urchin, removing dormant urchins and feeding them up in a lab setting.
Purple sea urchins are only one part of the problem, however. There are also warming ocean conditions, exacerbated by marine heat waves off the West Coast over the past decade. And while there have been hopeful sightings of young sunflower sea stars recently, these key predators have yet to make a clear recovery.
And even urchins as an explanation for kelp forest loss is not clear-cut.
Marion said there are plenty of urchin barrens now along Oregon’s southern coast, but there are also places where the urchin density appears normal. The Oregon Kelp Alliance’s report found kelp forests with high purple sea urchin populations that didn’t seem affected by the urchins.
Purple sea urchins off the Oregon coast.
Scott Groth / Oregon Department of Fish and Wildlife
Port Orford, a place Hamilton knows well, no longer has thriving kelp forests. Meanwhile, a spot near Cape Foulweather is bursting with life, the kelp seemingly doing better than ever.
When faced with so much loss elsewhere, Hamilton said the healthy forests and sea star sightings have been “surprising, confusing, exciting.”
Unfortunately, kelp forest loss is becoming a global problem. Fortunately, that means groups like the Oregon Kelp Alliance have a lot of examples of what has worked elsewhere and what they might want to try here.
Calvanese believes the tools the group is developing for Oregon could be successful.
“I cannot predict the future,” he said, adding, “but this is the beauty of being part of a global effort.”
There is evidence from places in New Zealand and elsewhere that focused removal of purple sea urchins can have a big impact. Calvanese said it’s important that Oregon Kelp Alliance take a systems approach, however, pulling at a lot of different levers.
“We are talking about an ecosystem that’s out of balance and our task is to restore that balance,” Calvanese said.
This story comes to you from the Northwest News Network, a collaboration between public media organizations in Oregon and Washington.
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