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Researchers Warn A Warming Ocean Threatens Giant Kelp Forests

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Giant Kelp have survived off the Southern California coast for hundreds of years, but the iconic plant may be in trouble as the ocean warms.

Speaker 1: 00:00 This is KPBS mid day edition. I'm Maureen Cavenaugh with Alison st. John, the warming climate is putting environmental pressure on California forests that have towered over the golden state for thousands of years, KPBS environment reporter Eric Anderson says underwater forests are facing the same kind of threat

Speaker 2: 00:21 At Parnell. Didn't have to walk far from San Diego scripts pier to find strands of giant kelp washed up on the beach. The root system is called the holdfast that holds the kelp plant to the bottom right there. You can see that they really aren't roots. The Scripps institution of oceanography biologist says that's how the algae stays anchored to the ocean floor. Once anchored, they grow up, basically it puts out these stipes and each individual state puts out these blades that then make it up to the surface for it to photosynthesize up near the surface. Small gas filled bubbles, carry the long stems to the surface where the blades can soak up. The sunshine. Darnell says giant kelp can grow up to two feet a day, making it one of the fastest growing, living things on the planet. The canopy depends on how much bottom hard bottom is located at the depth here off San Diego. We have the two largest kelp forest off the West coast because we have hard bottom that the calc can attach to and over large areas under water, the giant kelp forests off the coast of LA Jolla and point Loma can be spectacular. Biologists have compared them to an underwater forest of sequoias, but unlike the giant trees, kelp grows fast and dies fast. These young kelp that were videotaped just off the shores of San Diego are already reaching Skyward in the cool Pacific ocean.

Speaker 2: 01:50 Plants can quickly reach lengths of a hundred feet, but their life span is pretty short in this vital, but delicate ecosystem. Cornell says the kelp provide food and habitat, but the California, the bottom half house, a lot of habitat for species that live in the kelp forest over their entire lifetime Cornell says giant kelp in San Diego is under siege storms and sea urchins have taken a toll, but the potentially more devastating issue is heat. That's on full display at the end of scripts, pier where Sean Bruce was one of many people who performed a daily ritual. So the sample we take is about two feet off the bottom two to three feet off the bottom. The heavyweight ensures that no matter the surgery or the swell that day it'll stay in a fixed position. He's taking temperature readings of the ocean and those daily temperature readings show that the ocean has been warming here since the mid 1970s, temperatures hit a sustained peak in 2015 and 2016, and then set records just two years later, the heat is devastating for the fast growing kelp Cornell shared a video of a Rocky barren seabed near LA Jolla.

Speaker 2: 03:04 That is yet to recover from those heat waves. It's a Rocky area that should be full of kelp. And the problem is not limited to Southern California, Australia Tasmania, um, especially up in new England, um, also in Europe. And so it's a phenomenon that is affecting these ecosystems, uh, in both Northern and Southern hemispheres, Mark Carr studies, evolutionary biology at UC Santa Cruz. One of the consequences that warm water temperature has is it reduces the nutrient availability, um, to the algae and shallower waters. Southern California kelp are not yet at the point where they're struggling to survive, but the iconic underwater habitat is at risk. Climate science predicts oceans will continue to warm and data confirms that the trend has been underway for some time. That concern is whether we're now Glenda's started to experience more and more of these heat waves over time. Script's researcher, ed Parnell says the iconic kelp may already be in trouble and that could have a dramatic impact on the regions near shore habitat. They host hundreds of species themselves and Arthur provide. They provide shelter, habitat, and food for many, many species and losing the kelp forest will make the ocean a little less appealing to humans who dive in the underwater forests. We'll remove a small slice of the state's coastal tourism economy.

Speaker 1: 04:38 Joining me is KPBS environment reporter Eric Anderson and Eric. Welcome. Thank you. Now for those of us, who've never seen an underwater kelp forest. Can you describe what that looks like?

Speaker 2: 04:52 Well, I have to be honest here. I've never actually been in the water in a kelp forest before, but I've seen pictures and I've seen videos and, uh, a small representation at the Birch aquarium that big fish tank that they have, uh, the massive fish tank that has that like little stadium seating section in there that's designed to represent what a kelp forest would look like. And basically what it is is these huge long strands of kelp that, uh, reach from the floor of the ocean all the way up to the surface. Uh, and then you have all these different, uh, fish species that are, uh, both on the ground, on the floor of the ocean and swimming among the cow, et cetera.

Speaker 1: 05:34 And what makes the waters off San Diego's coast, such a good place for kelp forests to grow?

Speaker 2: 05:41 Uh, mainly it's, uh, two things. There is plenty of food there, uh, and there is what the biologists referred to as a Rocky substrate, which basically means that the floor is hard. There are rocks, uh, particularly in a couple of where you find the big kelp forest off the region off the coast of point Loma and off the coast of LA Jolla near where the children's pool is. There's a Rocky bottom there that allows the kelp to kind of grab on and hold on and, and grow toward the surface.

Speaker 1: 06:13 And what are some of those species that get their sustenance from San Diego's kelp forests?

Speaker 2: 06:19 Yeah, there are a lot of things that a live in and around and on the kelp forest sea urchins are often there. Um, you find things like a sea stars and enemies, crabs jellyfish. There are also, uh, lots of different kinds of rock fish that live, uh, in there. Uh, uh, seven Guild sharks. You'll see them in, uh, LA Jolla, uh, swimming through the kelp forest. You also see things like, uh, sea otters and occasionally a killer whale will look for refuge inside of a kelp forest. And then things that you may not think about that also rely on calc art, birds, crows, and starlings, and, and others who feed on the flies that are generated as some of that seek help washes up on the beach. So they're all also tied to the kelp forest as our goals and eat grits and even blue herons.

Speaker 1: 07:09 Well, so far this summer water temperatures have been unseasonably. Cool. Does that help kelp growth?

Speaker 2: 07:17 It does. In fact, uh, kelp grows better when the water is cooler and that's one of the things that has kept kelp thriving here off the coast of the California shoreline. It's the fact that the Pacific ocean is a very cool ocean and the temperatures are very cool. And that's what really is kind of, uh, at risk here with these increasing water temperatures, these long spells of warmer water that really sort of interrupt, uh, the growth, uh, the ability of the kelp to grow. And in some cases they actually, uh, Boris the kelp forest to shrink because they don't thrive very well. Uh, in that warmer water,

Speaker 1: 07:53 Are there signs then that the kelp forest and San Diego are already in trouble?

Speaker 2: 07:58 Yeah. And I think the thing that most biologists will point to is that a big heat wave back in 2015 and 2016, they called it the blob. It was this long, long swath of a super warm ocean water along the coast. It lasted long enough that it kept the kelp from kind of regenerating and areas that it normally would. And, uh, we talked to ed Parnell at scripts and he says, you can still see areas that were, the kelp was just eliminated and it just hasn't quite grown back. Um, and it doesn't help that there have been subsequent, uh, heat events like in 2018.

Speaker 1: 08:36 What are the main concerns of the script scientists you talked with about the future of kelp forest here in San Diego?

Speaker 2: 08:44 Well, kelp forests are kind of this iconic, uh, underwater feature. I know a lot of people don't typically see a kelp forest, uh, in its full glory, but it's this habitat that is very rich. Um, it generates a lot of nutrients. It feeds a lot of different species and it helps with the diversity of life, uh, along the California coast. And the concern is, is that if this habitat really gets restricted or shrunken or goes away, uh, that it's going to really hurt the ability of the under sea environment to be as diverse as it possibly can be.

Speaker 1: 09:20 You know, Eric, it seems that we're surrounded with so many more immediate problems these days. What would we lose if these spectacular underwater forests were to die off?

Speaker 2: 09:32 Well, you would lose that visual appeal. Of course, kelp forests are a wonderful place for people who are interested in scuba diving to go and see wildlife, but you lose a little piece of California as well. Help forests have been there for hundreds of years, and they've not only drawn a species in the ocean to them. They've also drawn people to them as well, who are just kind of amazed by the majesty that, uh, these, uh, underwater areas can be. I mean, you can see these long strands of calc, uh, reaching from the floor of the ocean, to the, the ocean surface and, and all this different activity, uh, in that habitat. And that would be going away. And not only would we be less rich for that, but it would really kind of change the underwater sphere just off the coast of California.

Speaker 1: 10:23 And I've been speaking with KPBS environment reporter Eric Anderson, Eric. Thank you.

Speaker 2: 10:28 My pleasure.

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KPBS Midday Edition Segments

Maureen Cavanaugh and Jade Hindmon host KPBS Midday Edition, a daily radio news magazine keeping San Diego in the know on everything from politics to the arts.