Episode 2 The Shrimp Problem Thursday, August 15, 2019 Listen / Update RequiredTo play audio, update browser or Flash plugin. A mysis shrimp (left) and a Daphnia (right) are shown under a microscope.Katie Senft / UC Davis Tahoe Environmental Research Center Summary Transcript Invasive shrimp are threatening Lake Tahoe. These are not the big white and orange crustaceans you get in a taco or on top of pasta. They’re called Mysis shrimp, and they’re voracious invaders that threaten Tahoe’s blue hue. If they stay and multiply, it’ll be hard to keep Tahoe from turning green. But if we remove them, they might also help other communities unlock climate change solutions. And the shrimp aren’t alone. They are joined by other invasive species, including three pound goldfish and cannibalistic bullfrogs. [Hair In The Wind theme song fades in] Brant: “I would love to go to sleep at night and not dream about shrimp.” [music speeds up] Ezra: “How many shrimp are we actually talking about? Millions? Billions?” Brant: “Probably trillions.” [music] Brant: We trawled in the fall / winter and we were able to pull out about three to three and a half million shrimp. That was a very small dent. Ezra: Humans put the shrimp into Lake Tahoe on purpose. Now UC Davis Scientist Brant Allen wants to take them out. It’s difficult work … but it could restore Lake Tahoe’s clarity and preserve its blue hue. Brant: “If we can improve it and actually go back to clarity that we had before. I would love to come over Echo Pass as a 60 year old and have it look like it did when I was four.” [Theme song continues] Dan: These aren’t just theories anymore. Stacy: I don’t want the snow to go away. Simon: Yes, Tahoe will change. Mary Ellen: I kind of feel like that endangered pika. Don: Tahoe doesn’t control climate change it’s a victim of it. Ezra: From Capital Public Radio. This is TahoeLand. Laurel: It always snowed by the third weekend in September, but that doesn’t happen anymore. McClintock: I want to see our forests restored. So, Tahoe doesn’t burn the way Paradise did. Maddie: Chasing the snow is a huge part. Devin: It’s about the lake that’s why everyone is here. Jesse: There are a lot of green lakes, there aren’t very many blue ones. Ezra: I’m Ezra David Romero. Lake Tahoe has a shrimp problem. But they’re not the big white and orange shrimp you get on a taco or on top of pasta. They’re called Mysis shrimp. Each one is about half an inch long and are almost translucent with big black eyes. They are voracious invaders and they’re changing the lake. Because of the shrimp, Tahoe’s water might become green and slimy instead of crystal clear. The shrimp, are a nuisance. If they stay and multiply, it’ll be hard to keep Tahoe blue. But if we remove them, that might be a solution. One other communities all over the world could learn from. The shrimp might be a clue to tackling the effects of climate change. Welcome to Tahoeland. [Theme music ends] Ezra: It's the middle of the night and I’m on a boat with Brant. We’re here to catch some shrimp. [boat engine in background begins] Brant: We’re headed south out of Tahoe City down to Emerald Bay. One of the more scenic parts on the lake.” Ezra: Introducing these little shrimp into the lake has completely changed the aquatic system. But, how did they even get here? Well it was the 1960s and authorities in California and Nevada put them in there as fish food. Brant: when I first got here I was working on the deep living lake trout and at certain times of the year they were stuffed full of these shrimp. Ezra: These shrimp don’t like light. So, they lurk near the bottom during the day. The lake is so deep that the fish can’t see them, so they don’t eat them. That whole fish food idea was a bust. And the shrimp population, boomed. When the sun sets, the shrimp travel to the surface. That’s why we’re out here at night. [Sound of birds in background] Brant: We just came into Emerald Bay and this is really one of the jewels of Lake Tahoe. We’re surrounded by snow capped peaks and the water here is just this beautiful emerald color. So this is where we’re working on the shrimp and we’re looking at how to harvest them most efficiently. [sound of the removal process on the boat] Ezra: The bad news is that the shrimp eat microscopic organisms called zooplankton that keep Lake Tahoe ’s water clear and blue. Brant: What we’re going to do is, we started down here kinda in the southwest part of the bay. We’re gonna transit the full deep length of the bay. When we get down to this end we’re gonna make a U-Turn. [Sounds of removing shrimp from the lake/boat engine] Ezra: This idea to remove the shrimp developed from a strange occurrence almost a decade ago. In 2011 the shrimp all but disappeared in Emerald Bay for no apparent reason. What happened next shocked researchers: the bay’s water clarity doubled. It was clearer than the rest of the lake. The shrimp came back though, and then the water got cloudy again. Now Brant’s team is working to re-enact that strange moment by removing the shrimp with nets at night. “Alright we got doors bring them in” [Sound of net coming out of water] Ezra: Katie Senft is one of the researchers. Katie: So, we’ll go ahead and get a five gallon bucket and put a little lake water in it. Cut open the bottom of the net so we can take a look at how many mysis we got. Ezra: Here’s Brant’s hypothesis: if they can take 75 percent of the shrimp out of the lake, its crystal clear glory measured in 1968 will return. Back then you could see over 100 feet into the lake. Ezra: That’s a lot of shrimp down there. Emily: And they’re moving. Ezra: Is this a typical night? Brant: In the fall we were averaging about six pounds per hour. This is probably about four pounds per hour somewhere in that range. Ezra: But can this project be scaled up? Brant says so. His way of doing it is sort of radical, but it kind of makes sense. Brant: “You could potentially use a whole fleet of autonomous boats that left their slip when recreational boating is done, go out and trawl or use other techniques like pumping shrimp up and treating them with UV light or using that warm water treatment. When they're done and maybe at 4:00 in the morning before recreational boating starts all of those autonomous boats go back and dock themselves in their slips. It sounds a little crazy, but the technology is there. Ezra: Envision a fleet of autonomous boats vacuuming up shrimp every night. They’re kind of like Roombas on the water. This would take a lot of money and a lot of time, but it’d be huge for tourism and the lake’s ecology. I asked Brant’s boss Geoff Schladow about this. Geoff: There's actually a lot of hope there. There is a way forward on clarity. Where this ties in with climate change is that if you have a lot of the native zooplankton back, then even if sediments are coming in at the surface, in a warmer lake, in a rain dominated system, they're set up to deal with that. It may seem odd, but it’s really saying the lake was doing perfectly well before we came here. Everything we can do to help it get back to how it was operating then can only be good.” [Music segway] Ezra: OK, lets take a step back. This episode is not just about shrimp. Although, I had no idea they were here in lake when I started reporting this project. There are persist leafy green aquarium plants in Lake Tahoe. They expand and take over the lake’s shorelines. There’s also cannibalistic Bull Frogs in Lake Tahoe and a whole slough of fish that just don’t belong. All these species are invaders and they’re changing the Lake Tahoe we know. But Tahoe’s not alone in the fight against invasive species. Creatures and plants are spreading all over the world as warming temperatures transform the places we love. In this episode we are going to look at the people who are fighting back against these species. So the first question our colleagues asked us when we started this story was, “Can we eat the shrimp?” So our data reporter Emily and I, tried them. Ezra: Honestly they don't taste like anything. Emily: They feel like something though. Ezra: You're right, they're not good. Brandon: You're right, I don't like it. Ezra: Emily is here with me now to relive this experience. What up shrimpet? Emily: What up Shrimpet. So I think the question here isn’t if you can’t eat the shrimp, but if you should eat the shrimp. So they were really gross. And it was kind of like chewing on crunchy, oily bugs. And I really don’t know how we talked ourselves into doing this. Ezra: Yea, I don’t either. They were pretty gross. But once we mentioned it to the UC Davis team, they were like “Do it.” Emily: Yea, there was no going back. Ezra: Before we get into the process of all of this, let me get this straight, people put the shrimp into the lake and now we’re living with the consequences when you go visit Lake Tahoe. What else did you learn about this? Emily: So I spoke with one of the parties that’s responsible for putting the shrimp in the lake, The Nevada department of wildlife. And they teamed up with the California department of wildlife in the 60s to put these shrimp in the lake. And they know now that they messed up. They’ve seen the consequences and the biologists who were involved in it, feel remorseful. But basically hindsight is 20/20 and they just didn’t understand then like we do now, what these shrimp could do. Ezra: So instead of being this great fish food, they’re also eating these zooplankton, right? And the zooplankton help clear the lake. But, how do they do that? Emily: Yeah, so these zooplankton, they’re called daphnia, and they’re kind of like water fleas. And they play this huge role in clearing the lake. So they eat the algae and dirt that makes it’s way into the water, and then they poop it out and these little poop pellets fall to the bottom of the lake. So basically, daphnia poop, through this gross process is cleaning the lake water. Ezra: They’re kind of like little vacuums. Emily: Yep! That is exactly what it’s like. And that’s part of why Lake Tahoe is so clear. The other really cool thing about these daphnia is that they’re kind of crustacean feminists. Ezra: What? Emily: Yea, so, daphnia are this kind of matriarchal species because they can reproduce normally between females and males, but when there’s a lot of food and they really want to boost that population, female daphnia can just clone themselves and produce tons of tiny clone daughters. Ezra: So they’re just like what, I don’t need a man to boost my population. Emily: Exactly. But there were literally zero daphnia per cubic meter in Emerald Bay at last count. There should be thousands of them. Ezra: Wow how come so little? What’s going on? Emily: So these are some hungry shrimp and they have eaten up all these daphnia. Katie Senft from UC Davis explained it to me in a way that really made sense. Daphnia, they’re kind of like cows: they’re really slow, but they’re also really efficient at eating. Meanwhile the other zooplankton, they’re kind of like rabbits. They just zip around really fast. Here’s Katie: Katie: “So if you're a mysis shrimp swimming through at night, who are you going to eat? You’re gonna eat the cow. But then you have these inefficient grazers, the rabbits that are left and the field gets overgrown, and you lose your clarity.” Ezra: So is this problem fixable? Emily: So we started off this podcast in Emerald Bay, where Brant Allen is trying to see how we could reduce the shrimp population. He would really like to see the number of shrimp down to about 25 per square meter, but that would be a huge reduction from where we’re at now. If we got the shrimp down to the level that he wants, the daphnia population would grow back and they could clear the lake like they’re meant to. Ezra: And that would totally change Emerald Bay and if it went to Lake Tahoe, this could be a solution for clearing the rest of the lake, right? Emily: Yeah, yeah. Ezra: So you’re obviously obsessed with shrimp now. I hear you even have an outfit! Emily: It is a Crawdad outfit Ezra. Ezra: But I understand that you have some more work that people could look at. Emily: Yeah, so my shrimp fascination has manifested as an article. It’s at capradio.org/tahoelandshrimp, and if you go there you can find some really awesome videos, photos and graphics to help you understand the huge impact these shrimp are having on the lake. Ezra: Yeah, the graphics are awesome. I love how the fish move and the shrimp go up and down. You can see the levels, it’s really cool. Thanks for joining me today and talking about shrimp and telling me about your obsession. Emily: Of course Ezra, I am ready to talk about shrimp and Daphnia, always. Thanks. [Music begins] [Sound of walking through mud and in the water] Ezra: Even if the shrimp get under control … there are still other invasive species in the lake. Like crawdads, bass, catfish and three pound goldfish. And then there are these cannibalistic bullfrogs. Sarah Muskopf and I are attempting to catch some bullfrogs at Taylor Creek on the southwest side of the lake. [Sound of water splashing] Sarah: Oh, yuck. There it is. Did you see it was right in front of us… There it is! Ezra: Get it, get it! I saw it. Oh my gosh. It was ugly, it was huge. Sarah: I almost stepped on it.. Ezra: Sarah’s an aquatic biologist with the Forest Service in the basin. She says Taylor Creek has the largest population of American Bullfrogs in all of Tahoe. Sarah: They're considered one of the 100 most voracious invaders in the United States. They're the largest frog in North America. They're cannibalistic. They say about 80 percent of their diet is other bullfrogs. Ezra: We’re hunting them because Taylor Creek embodies all of Tahoe’s climate change challenges. Sarah: Every warm water invasive fish that we have in the basin is also present in this system. The good, the bad, and the ugly are all here. Reaping the benefits of this really great habitat. Ezra: They do so well because the shallow water warms fast. As the climate changes, this creek will most likely be dominated by non-native species. Sarah: Taylor Creek has the highest temperatures of any stream to date. So although it's had some cold water habitat right now, come August it's reaching that threshold where it's lethal temperatures to a lot of our native species. But not our warm water species. Ezra: Lethal temperatures.That mean more predators and plants crowding out native ones. That’s why we’re chasing bullfrogs. Sarah wants to give native species a fighting chance to thrive, even as temperatures change. [Sound of water splashing] Ezra: What’d you get? Sarah: Nothing. Ezra/Sarah: Laugh Ezra: Oh, you were great. [Music begins] Ezra: Invasive species aren’t just threatening Tahoe. They’re spreading around the world and if they aren’t controlled the invasions could intensify. Carrie Brown-Lima is the director of the New York invasive species Research Institute based at Cornell University. Carrie: The looming fear is really of a species that has nothing to keep it in check. Ezra: Carrie says removing invasive species is tough. Scientists are often just learning how climate change is influencing them. And the fear is that species will spread to new ecosystems. Carrie: The projections show the northeast is probably one of the areas that the climate is going to change more and become better for a lot of these invasives to move north where in fact it might become too warm for other invasives to take over in the south. Ezra: This reminds me of the bark beetle that killed more than 129 million pine trees in California during the recent multi-year drought. A similar bug is moving north on the east coast. It’s called the Southern Pine Beetle. Carrie: I was speaking with a researcher who studied this. He lives in New Hampshire and he says you know every year I have to drive less to reach my research sites just because this species has just been moving north at such a steady rate. Ezra: I think one of the most fascinating cases of invasive species has to do with snakes in Florida. Carrie: Florida is a really crazy invasive species hotspot. The Burmese python escaped into the wild and it's just been able to reproduce. Apparently the climate in Florida is perfect for them throughout the Everglades. It's just been really feeding on all of their native small mammals which is their normal prey but our mammals here aren't adapted to them. Ezra: And that’s why Carrie says it’s important that we take action. Carrie: Sometimes invasive species seem like this insurmountable problem and yes we're never going to get rid of all the invasive species, but we can slow their spread. And we do have a role and a responsibility in that. [music transitions] Ezra: Let’s talk about responsibility for a second. We haven't always been great stewards of Lake Tahoe. But there is work being done. We're doing more boat checks to make sure invasive species don't make it into the lake. But Jesse Patterson says more can be done. He's the Keep Tahoe Blue guy from episode one. [Sound of Jesse pumping air into blow up paddle boards] Jesse: Pump it up. It’s a workout. Tahoe bootcamp. Ezra: We’re pumping up blow-up paddleboards as fast as we can because mosquitos are fierce here. We need to get moving. Ezra: They’re pretty big. You can feel them biting you. [Sound of them paddling through the water] Ezra: We’re making our way down the Truckee River in South Lake Tahoe. It’s hard to tell from the paddleboard, that a subdivision of homes is on the other side of the trees. It looks just like a forest. Jesse: Focus up here, yeah just don’t hit the bushes is basically what that means. Ezra: So, go wide? Jesse: Be the river. Ezra: Be the river Ezra. Ezra: Right when we got into the water something crazy happened. A black bear crossed the river in front of us. Ezra: “There is? A bear. That’s cool. Might of been the same bear I saw earlier.” Ezra: We’re paddling to what Jesse says is the Venice of Tahoe. It’s called the Tahoe Keys. It was one of Tahoe’s biggest wetlands and a large part of it was dredged in the 50s and 60s and then replaced with 1,500 homes alongside canals. Jesse: The tahoe keys is a poster child of a mistake. It was done you know not with ill intention it was just put in a bad location particularly within this giant Marsh meadow that used to be a filter. Not only did we remove the filter and break it. Essentially we added pollution on top of it. Ezra: Today the Tahoe Keys pose a new threat to the lake’s pristine shoreline. The shallow warm canal water is perfect for invasive fish and weeds to flourish. [Sound of boat engine] Jesse: Boat traffic jam. Ezra: With so many people coming in and out of the Keys boat propellers chop up the weeds. Ezra: “So, the problem is all these pieces of plants on top of the water?” Jesse: Yep, that’s it. These are the fragments and if you’re like why do these little fragments matter? If you look at some of them they have already sprung roots. Every one of these fragments can turn into a new plant, they can turn into a new infestation. Before climate change there wasn’t much space for them out there. Now, the lakes a lot warmer and we’re finding more and more places where these plants can establish and grow and spread. Ezra: Each little fragment can ruin a whole beach. Imagine walking up to the shore and instead of seeing slabs of granite through the water, you see a gooey green mess. The weeds change the soil, the water turns green and then invasive fish come. Jesse: The main reason now is that the lakes warming up so the conditions outside the lake along the shoreline are now much more similar to what's inside these man made lagoons. Particularly in the last five years, our average water temperature Tahoe has increased 10 times faster than the previous 40. Ezra: The Tahoe Keys are here to stay. That’s why there’s an effort to figure out ways to stop these little shards from leaving the lagoons. It’s all about buying time until a long term solution emerges. One idea: bubbles. Jesse: There’s a perforated tube running the length of the channel and creating a wall of tiny bubbles that goes all the way to the surface and the plant fragments floating anywhere in the water column can’t get past it. They get pushed to the top and then to the edges. If you look right over to the side now, it’ll get pushed right into the sea-bin right over there. It’s like a fancy trash can. Ezra: There might be other ideas too. They’re choking out the plants with black mats, mowing the weeds with an underwater trimmer and thinking about using a water based herbicide. [Music comes in] Ezra: But what everyone pointed out to me… the best way to keep invasive plants and animals out of Lake Tahoe is to never put them there in the first place. And yeah that’s a simple idea ... but so many species have been added to the lake by us. [Music beat drops and continues] These first two episodes of TahoeLand have been all about the lake. And for good reason: the lake influences everything here. But tons of people come here for other reasons, like the mountains and the snow. So in our next episode we’re going skiing, with an olympian. Maddie: Right leg, There you go. Now stay in the pizza. Now, left leg. Good, good. Right leg. Woo! Good job. Left leg. Ezra: AHHH! Maddie: Good save. Ezra: I almost died. Ezra: Don’t forget to stick around after the credits for a Tahoe Tidbit on what might be the lake’s biggest invasive species. Our digital producer Kacey Sycamore will unlock that mystery. TahoeLand is edited by Nick Miller. Sally Schilling is our podcast producer. Our Digital Editor is Chris Hagan. Emily Zentner is TahoeLand’s data reporter. Kacey Sycamore is collecting your questions about Tahoe and answering them. Our web site is built by Renee Thompson, Veronika Nagy and Katie Kidwell. Linnea Edmeier is the executive editor. Joe Barr is our Chief Content Officer. And our associate producer is Gabriela Fernandez. Our music is by artist Charlesthefirst. He’s from Tahoe. To make sure you don’t miss any episodes, subscribe on Apple Podcasts or wherever you listen. Check out our website, capradio.org/tahoeland for videos, photos, additional stories and more. I’m Ezra David Romero…. Thanks for listening to TahoeLand... from Capital Public Radio. [Music ends] Kacey: Tahoe Tessie. She’s Tahoe’s version of the Loch Ness Monster, or Nessie as the Scots call her. With help from our friends at KQED’s Bay Curious podcast, we put a call out for your questions about Lake Tahoe. Allison Savage from San Francisco wrote in and wanted to know: what’s the history behind the Tessie legend? I’m Kacey Sycamore, interactive producer for CapRadio, and for this Tahoe tidbit we get to the bottom of Allison’s question. Remember Tahoe historian Dave Antonucci from the first episode? He said, Dave: “The bottom line on this is that there’s no prehistoric monster in Lake Tahoe. However, there’s something.” Kacey: Dave points out that Lake Tahoe is only a couple of million years old, so if there’s a monster living in the lake, there’s no way it’s prehistoric. But Dave says about 50 years ago, people started reporting sightings of something “large, indescript, and kind of prehistoric-looking” in the lake. Dave: “Some of these can be explained as shadows on the water or waves or debris like a log or something like that, but others were a little more credible. Some of em came from people I know, so I knew that there was something there.” Kacey: His best guess at what that something is? A big fish called a sturgeon. Antonucci: “It’s been around for a long time, and if you've seen one, it kind of has a prehistoric look to it. It's kind of scaly, with large fins and kind of a dinosaur-looking snout. They grow quite large. They can grow up to 22 feet long, and the conditions in Lake Tahoe are such that they could survive.” Kacey: OK, so Tessie might be a sturgeon. But I wondered… are there any photos to back any of this up? Dave: “Of course not. (laughs) Maybe someday we’ll get it with cell phones that have cameras but I’ve never seen any photographic evidence of it at all. And if somebody ever gets a picture, that would be interesting.” Kacey: So if you spot Tessie, send us a picture. In the meantime, you can see a photo of a sturgeon, and find more answers to your questions about Tahoe, at capradio.org/tahoeland. Trillions Of Invasive Shrimp Are Degrading Lake Tahoe’s Clarity. Now Researchers Are Trying To Stop Them. August 15, 2019 | Emily Zentner Mysis shrimp, an invasive species put in Lake Tahoe by humans, have gobbled up the tiny creatures that keep the lake clear. Can we control the shrimp population enough to fix the problem?