Oregon is known for its terrestrial forests, but there’s an equally important forest ecosystem in its oceans: kelp.
Kelp forests provide a crucial food source and habitat for marine species, helping to support coastal biodiversity as well as the state’s fishing and tourism industries. But along some parts of the coast, these forests are in decline. Sarah Gravem is a research associate at Oregon State University and a leader with the Oregon Kelp Alliance. She joins us to talk about how the organization is working to bring kelp back from the brink.
The following transcript was created by a computer and edited by a volunteer:
Dave Miller: From the Gert Boyle Studio at OPB. I’m Dave Miller. This is Think Out Loud. Forests in decline, habitat being lost, an ecosystem in danger of collapsing. It sounds like a familiar story, one we’ve talked about many times and one we’re going to return to right now, but this time with a twist. The forests in question are underwater. They are kelp forests, and their decline up and down the Pacific Coast is alarming scientists, Tribal members, fishermen, divers and many other people. They say there is an urgent need to promote kelp reforestation before this problem gets worse. Dr. Sarah Gravem joins us to talk about this. She is a research associate at Oregon State University and a leader with the Oregon Kelp Alliance. Sarah Gravem, welcome.
Sarah Gravem: Thanks for having me.
Miller: Before we get to the ecology, can you just give us a sense for what a healthy kelp forest looks like?
Gravem: Yeah, diving through a kelp forest is a really, really neat experience. It’s this 3-D forest that you, unlike a terrestrial forest, can swim through. The kelp can grow at least 30-60 ft long, reaching all the way from the bottom where they have these little root balls, all the way to the surface, and they make this big canopy. Light filters through and makes it all sorts of shimmering greens and blues, and the sunlight coming through like dappled rays is just otherworldly.
Miller: Otherworldly, but one of the remarkable things here is it really … forest seems like the right word for it. I mean, with the vertical trunks of this kelp going straight up, it really does seem like just a watery version of a terrestrial forest.
Gravem: Yeah, it is a forest. We like to say in ORKA that kelp are the trees of the sea. And in some ways they’re even better than trees, because while they make big forests that all sorts of things use to live in, they’re also edible. Unlike most trees are not. You don’t see animals just munching tree leaves very often, unless they’re bucks.
Miller: We do get berries, but most of us are not eating the trunks.
Gravem: Right, no one’s eating the trunks.
Miller: You mentioned habitat. What role does kelp play in a marine ecosystem?
Gravem: Yeah, they are first and foremost habitat forming and so they serve two functions as habitat. So there’s animals that just live in the kelp forest. There’s all sorts of fishes that make a given patch of kelp forest their home. And you’d be surprised when you dive a spot over and over and again, you realize the fish actually have homes. They don’t just wander around in the ocean aimlessly. They have a little spot, and they have their favorite rock, and they have their favorite kelp frond, and they hang out there. So that’s one way that the animals all around use their habitats, that habitat. There’s also all sorts of snails and slugs and things that climb the kelp blades and use it as habitat and foraging, eat the kelp. And then another really big and underappreciated role of kelp is as a nursery. So all sorts of fishes, crabs, and all sorts of other things actually land in the kelp as little babies and use it to hide in as they grow up. And then they eventually might leave, but without the kelp, there’s nowhere for them to hide when they’re babies and they’re really vulnerable at that phase.
Miller: From that first question, I’ve asked you to describe a healthy kelp forest with the kelp going all the way to the surface and the light filtering down with different shades of green or blue. What does an unhealthy kelp forest, or a place where the kelp has died, what does that look like?
Gravem: Yeah. So that healthy kelp forest, like I said, supports all sorts of things like fishes. There’s also abalone on the ground, sea urchins on the ground, if you’re down in Southern California, lobster, all sorts of things if you have a healthy kelp forest. But when that kelp is gone, there’s not much for anybody to eat and there’s not much for anybody to hide in. And so a lot of the animals that hide in it will just be gone, all the fishes, especially. And then if there’s nothing to eat, things like abalone aren’t doing so well. They’ll either leave or hide and all sorts of things that like to forge on the bottom, like crabs and lobsters and stuff, also have nothing to find to eat and they have nothing to hide in. So they take a hike, too. And what you end up with is often what we call a sea urchin barren, which … so, sea urchins are kelp eaters and when the kelp gets low, they start coming out of their crevices and roaming the sea bottom and just scouring anything left. And when you have no kelp, you end up with sea urchins all over the bottom and it just ends up being mostly their rock, or rock covered in this pink crusty algae that’s kind of hard to eat, and it’s just not, it’s not a forest anymore.
Miller: How widespread is the marine landscape you’ve just described? How widespread is the dieoff of these kelp forests?
Gravem: Yeah, so the kelp forests in Oregon do already occur in sort of patches along the coastline where there’s rocky habitat bottom, and they have declined in several places. The estimate on the west coast in general is like 60-90% decline in kelp, depending on where you are. And many of Oregon’s reefs have also declined really substantially, to the point where there’s no kelp left. In several places, there’s a handful of reefs that are still doing okay. Like, Cape Arago and Rogue Reef are still doing okay. But they have a lot of urchins and we don’t know whether they’re going to last much longer. So this urchin barren state has really become much more prevalent in the last five years or so than it used to be.
Miller: What are the different factors that are causing kelp forests to decline?
Gravem: Yeah, the two big ones. Well, maybe three big ones. One is climate change. So, climate change is bad for kelp, because kelp love nutrient rich cold water. They’re plants that get their nutrients straight from the water rather than from the soil. There’s no soil, so they need nutrients and nutrients are in cold water. And when you have global warming, you get things like warm water events. Marine heatwaves. There was one big one called The Blob back in 2015-16, and that just wipes kelp out directly. It kills them. But they’re usually pretty good at growing back. They’re an annual species like a tomato. So they make spores or seeds and they grow back every year, but in 2015 and 16, they got killed. And when they came back, they were met by just sea urchins everywhere. And the reason we think there were sea urchins everywhere is because back in 2013 and 14 – so a little bit before The Blob – there was this disease that swept through called sea star wasting disease, and it killed one of the main sea urchin predators that existed in our local reefs, the sunflower sea star. And so without the sunflower sea star– and when I say killed, like, it’s gone. There is 100% mortality from something that used to be a dime a dozen. And they’re gone in Oregon. They still exist up in Alaska. – but they eat sea urchins, and they scare sea urchins, and without them the sea urchin populations increased and they became more brave because there’s nobody eating them anymore. And then they became super numerous. Then the kelp died and as the baby kelps are trying to come back, they’re just being met with a hungry, hungry horde of spiky mouths.
Miller: I mean it’s such a perfect – if that’s the right word – example of the interrelatedness of any ecosystem. And I imagine it’s even more complicated than you have just outlined. But we can just see that sort of cascade of effects when one thing happens. And I remember – I don’t know, 7, 8, 9 years ago – talking about the sea star wasting and now as you’re pointing out, we are hearing just the knock on effects of that. The ecological impacts of what you’re talking about could be really profound in terms of the loss of the habitat and this whole complex ecosystem that you’ve been describing. What could this also mean for fishing or for tourism or for the coastal economies more broadly?
Gravem: Yeah. So the Oregon Kelp Alliance is actually unique in that we’re a bunch of scientists that also … starts with a bunch of scientists, but we are really incorporating those people that you just mentioned. So the fishermen, the tour guides, the Tribal members, that are all dependent on this ecosystem for their livelihoods. So we have folks from kayaking tours and whale watching tours that are in our group, and fishermen who no longer can get sea urchins with good uni inside because there’s nothing for the sea urchins to eat, or that fish rockfish and the baby rockfish aren’t coming in anymore so their catch is threatened. So all sorts of different people are really interested in getting this ecosystem back, not just for the ecological stability and health of the ocean system, but for the health of the coastal economies and the cultural interests of the Tribes as well.
Miller: One of the things that I’ve seen or heard that people in the alliance are doing is going down with hammers to smash sea urchins, but I read in KMUN Report that there could be 250 million urchins in just one large reef near Port Orford. So smashing one by one, that that seems mathematically impossible. What options do you have for kelp reforestation?
Gravem: Right. Yeah. So this is a big issue, and we are starting an urgent culling project, but we don’t think that that’s going to be the answer. So one main thing to think about, like I said a moment ago, kelp are an annual species. So they’re making babies every year and regrowing every year. And so if you have no healthy adult kelp forests on a whole stretch of coastline … I mean we don’t know how long that’s, quote unquote, ‘seed bank’ lasts, but we think it’ll be helped a lot if we at least have patches of reef along the coastline that do have kelp left so that those kelp can create conditions for other places nearby to survive and have seed, essentially. So yes, we’re not going to smash all the urchins, and we don’t want to smash all the urchins. They’re part of the ecosystem too. There’s nothing wrong with urchins, but they’re becoming so populated that none of the kelp can get a hold. And so we’re going and having really, really focused small-scale culling events where we do go down and literally smash them with a hammer to at least clear small patches so that the kelp can grow in little oases, and that can serve as the source of new kelp in the future.
Miller: Dr. Gravem, thank you.
Gravem: Yes.
Miller: Dr. Sarah Gravem is a research associate at Oregon State University and a leader with the Oregon Kelp Alliance.
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