IRA FLATOW: This is Science Friday. I’m Ira Flatow. If cabin fever is getting you down, if winter has you cooped up, if you’re reaching to take your mind elsewhere, you are in luck. Our biennial Science Friday Book Club is back for the dark, dreary winter reading season. And this summer, remember, we sent you out birding.

Now it’s time to take you on a new adventure. How about the shores of the largest freshwater resource on the surface of the planet? The Great Lakes. The Great Lakes hold more than one fifth of all the surface freshwater on Earth, enough water to submerge the entire lower 48 under 9 and 1/2 feet.

Well, have I whetted your appetite? Our book is Dan Egan’s 2016 book, The Death and Life of the Great Lakes. Producer Christie Taylor, a proud Great Lakes Wisconsinite, is our guide. Take it away, Christie. Tell us about this book.

CHRISTIE TAYLOR: Hey, Ira. So the first thing I actually have to do is tell you about the lakes themselves. Like you said, I grew up in Wisconsin, and I spent every single summer on the shores of Lake Michigan for a lot of my childhood. I’ll never forget standing on the beach and trying to see the other side, even though that– spoiler alert– is actually impossible in most parts of the lakes. Or also watching ships that seemed as big as ocean liners drifting by on the horizon.

The Great Lakes are so big, Ira, that they influence weather systems. They generate heavy snowfall in some parts of the country, including Buffalo, where I think you’ve been. And under stormy skies, they have sunk literally thousands of ships, including the Edmund Fitzgerald in 1975.

IRA FLATOW: Famous one.

CHRISTIE TAYLOR: Yeah. Yeah. There’s a song about it. And if you drive around their circumference, it’ll take you days, and you’ll pass through dozens and dozens of different kinds of landscape in the process. They are big. They are very big.

And if you live anywhere near the Great Lakes, you also know that you’ve basically got an ocean in your backyard. It’s an ocean that supplies drinking water, however, for 40 million people, plus the usual boating, fishing, swimming, and most of the time, stunning natural splendor.

But if you read Danny Egan’s book, The Death and Life of the Great Lakes, you start to understand that these lakes, big as they are and beautiful as they are, they’re not healthy at all. They’re full of invasive species that are sucking the nutrients right out of the water, and agricultural runoff is spurring noxious algae blooms that can poison water supplies. Take the city of Toledo in 2014 when half a million people couldn’t drink their tap water, even if they boiled it. And then there’s the always looming threat of invasive carp.

So we have two guests here to help unpack what’s troubling the lakes these days, what’s hopeful, and, hopefully, help people get excited to start reading Dan Egan’s book with our book club. We have Peter Annin, director of the Mary Griggs Burke Center for Freshwater Innovation at Northland College in Ashland, Wisconsin, on the shores of Lake Superior. Welcome back, Peter.

PETER ANNIN: Thank you. Good to be here.

CHRISTIE TAYLOR: Thank you. And Dr. Donna Kashian, professor of biological sciences at Wayne State University in Detroit. That’s at the conjunction between Lakes Huron and Eerie. Welcome back, Donna.

DONNA KASHIAN: Thank you. It’s great to be here.

CHRISTIE TAYLOR: Thank you both for coming back. So first of all, Peter, take us to the scene. Why are the Great Lakes such an important natural resource? How do you explain them to people who don’t live anywhere near them?

PETER ANNIN: Yeah, well, as Ira said in his intro, 20%, one fifth of all the fresh surface water on the planet, just an enormous, not just national, but continental and globally significant resource. Again, as you said, nearly 10 feet. That’s enough water to cover the lower 48 states, nearly 10 feet. Superior alone holds 10% of all the fresh surface water on the planet.

The lakes have 35,000 gorgeous islands. Georgian Bay and Northern Lake Huron has 30,000 alone. It’s really– Lake Erie has one of the largest freshwater fisheries in the world. So it’s really a gorgeous, thriving, superlative place in much of the Great Lakes basin. But as you mentioned, there are places where the Great Lakes are hurting, and they need our help.

CHRISTIE TAYLOR: Mm-hmm. And Donna Kashian, tell us more about that hurt. What’s been not so great for the Great Lakes in recent years?

DONNA KASHIAN: Well, the Great Lakes have been suffering from a lot of impacts, multiple ones at every angle. Invasive species have been one of the largest impacts that have changed the structure of the species that live within the lake. Then we are seeing massive harmful algal blooms affecting drinking water. We’re seeing contaminants in the fish. So some fish are no longer, really, you want to eat them because of it, while some other fish are still lower in contaminants. Changes along the shorelines, losses of wetlands, climate change, fluctuating water levels that are beyond the normal fluctuations in water levels with climate change. So a lot of things have changed, but they still move forward.

CHRISTIE TAYLOR: Mm-hmm. Looking at invasive species specifically, The Death and Life of the Great Lakes unpacks a lot of how they got here. They arrived from the ocean after all the shipping channels were created 100 years ago. Others are arriving in ballast water from cargo ships– bloodsucking sea lampreys, tiny ale waves. Either of you have a favorite, I guess, bad guy for what maybe has caused the most damage in these lakes?

PETER ANNIN: Yeah, I think the two– go ahead.

CHRISTIE TAYLOR: Donna first.

DONNA KASHIAN: Sorry. In my opinion, the number one to me is the invasive mussels, the zebra and quagga mussels, the Dreissenids, followed really closely by the lamprey as the biggest impacts, where those two species take this impact where the lamprey affect the higher trophic levels, taking a top-down approach to the impacts, while the Dreissenids, or the zebra mussels and quagga mussels affect the bottom of the food chain, like nutrients. So in the process, the two groups are squeezing out the middle of the food chain and creating dramatic impacts on the lake.

CHRISTIE TAYLOR: Peter, did you have another nomination for that?

PETER ANNIN: No, actually, I was going to agree. You know, there’ve been a hundred and plus, more than 180 non-native species introduced to the lakes, but the two big ones, the two big game changers, system-wide game changers have been the lamprey and the zebra mussel. And the big concern is that we may have another big game changer knocking on the door with Asian carp. And Dan writes about that in the book as well.

CHRISTIE TAYLOR: Mm-hmm. And we’ll talk about carp, for sure. These lampreys, does anyone want to– I mean, they’re so gross in some ways, and they did so much damage to the lake trout stock. But who are the fish that we’re trying to save at this point? What is the native fishery? What are those fish that we’re trying to help recover? Donna?

DONNA KASHIAN: So the first– a lot of the lake trout, the native species of the larger predatory fish have been really reduced. And so we’ve taken steps to, as those populations have dropped, to introduce new species, like the salmon species, in the lakes to recover the fisheries that have been lost due to the lamprey. So the trout and a lot of the bigger fish. The top predators, again, are the ones that have been most affected. But with the top predators affected, it moves down the food chain, again, and affecting all the species of fish.

CHRISTIE TAYLOR: I really love the story of the salmon fishery in the Great Lakes. These are Pacific salmon, I should clarify, like Coho and Chinook salmon. And one guy, basically, got to decide that instead of restoring lake trout, we were going to put salmon in the lakes. Peter, how did that happen?

PETER ANNIN: Yeah, when the lamprey came in and knocked out the top predators, Donna said the lake trout, that threw the lakes’ ecosystem and food web completely out of balance. So then we had another non-native species prey fish, the alewife, that exploded. And the populations were dying off and washing up on beaches in the Great Lakes, and they were bulldozing these stinky piles off of the beaches in the 1960s. And it really turned people away from the lake. So there was somewhat of a food web emergency.

And so you had people in Michigan pumping these Pacific salmon, which are eating machines, especially the Chinook, or the Kings, as they’re known in Alaska, into the lakes to beat back this alewife population. And so now we have sort of the native species predator-prey relationship in the fishery competing with the non-native species predator-prey relationship in the lakes. And there are people in the Great Lakes region who have grown up catching these Pacific salmon who think they are actually a native species in the Great Lakes, and obviously, they’re not.

CHRISTIE TAYLOR: Donna, you mentioned the zebra and quagga mussels, and they play a role in the algae blooms that we were seeing in Lake Erie, isn’t that correct?

DONNA KASHIAN: Yeah, they have a lot of impacts on the lakes. And one of them that has been linked is through the increase in harmful algal blooms. And there’s a lot of different mechanisms going on. One thing that happens in the type of algae we have, the mussels come in and they filter the water, making it more clear. So we have some of the algae that grows on the bottom, or the benthic algae, flourishing because the light is hitting the bottom now.

But then we also have the cyanobacteria, or what used to be called the blue-greens, or the harmful toxin-producing algaes that mussels can actually reject. So they will take in the healthy, the green algae that doesn’t produce toxins and eat those, but spit back the cyanobacteria that produce the toxin. So it’s creating this dynamic where it’s facilitating these blooms even further by multiple mechanisms.

CHRISTIE TAYLOR: Mm-hmm. And Peter, you’re the author of a book called The Great Lakes Water Wars, which is about the worries about the water supply in the lakes. Is this just about chemicals? Is this just about pollution and invasive species? Or is there something else in this story?

PETER ANNIN: Yeah, it’s really the idea that with 20% of all the fresh surface water, as we continue to enter a period of a global water crisis, and some parts of the continent are also entering a period of severe water stress, that there might be a run on Great Lakes water in a way that could harm the ecosystem of the Great Lakes rather significantly. There’s been a lot of paranoia about that in the Great Lakes region for decades and decades.

And so 2008, a Great Lakes Compact was adopted by Congress and signed by the President, creating a legal water fence around the edge of the Great Lakes watershed, preventing long-range large-scale diversions out of the Great Lakes basin and keeping that water inside the watershed for the people and the ecosystem and the economy this year.

CHRISTIE TAYLOR: That was a pretty bipartisan act, wasn’t it?

PETER ANNIN: It was an extraordinary bipartisan act, yeah. And what you see in the Great Lakes region, it’s one of the last bastions of bipartisanship in the country when it comes to the environment, environmental policy.

And it’s remarkable to go to the Hill and see on Great Lakes Days, which is in early March every year, this line of members of Congress who come and testify on behalf of the Great Lakes to the advocates who are there. And it’s incredibly bipartisan, and really quite a remarkable thing in the partisan era that we’re in today.

CHRISTIE TAYLOR: Mm-hmm. Looking at the water supply, I mean, one question I have, though, is, haven’t water levels been extremely high on the lakes the last couple of years? Is there really a worry about the supply?

PETER ANNIN: Yeah, well, so first of all, with the Compact now in place, there is much less worry about a supply. And that’s right, water levels vary naturally in the Great Lakes basin, to a degree that drives humans crazy, but it’s actually very good for the environment that the ecosystem here has thrived and evolved based on that natural water variability. But it’s significant.

The difference between, say, the all-time high water level and all-time low water level on Lakes Michigan and Huron is more than six vertical feet. So if you live on a cliff, that’s six vertical feet, but if you’re on a gradually sloping shoreline, it can be 100 yards difference between where the water was, quote unquote, “when I was a kid” and where water is today.

And today, we are definitely dealing with very significant water supply issues. There are stories daily about people, marinas, people who are living and working on the shoreline dealing with this really record-breaking or near record-breaking high water levels. We’re at a high water period. We were in a record low water period in 2013. And that’s part of living with the Great Lakes. But what we’re seeing is more volatility in water level changes more recently, and that’s really a cause for concern.

CHRISTIE TAYLOR: Thank you. Just interrupting to remind everyone I’m Christie Taylor. This is Science Friday from WNYC Studios. Talking about the Great Lakes and the ecological changes of the last decades.

Donna, before we go, the lakes have changed so profoundly in a century of human interference, but you’re saying that there’s still a lot of positive things happening, there are things to look forward to. Why aren’t the Great Lakes a doomsday story yet?

DONNA KASHIAN: Well, I think they’re, in some ways, getting close to doomsday in some ways. But there are other aspects we’ve seen really improving. The problems of the ’70s– Cuyahoga River catching on fire multiple times, contaminates– so PCBs have gone down. We’ve seen improvements in PCB levels in the eggs of herring gulls. DDE, which is a breakdown product of DDT, which is used for a lot of pesticides on mosquitoes, historically, we’ve seen those levels go down. Mercury is going down in the water. We’ve seen bald eagles, peregrine falcons, ospreys having higher fledgling years. We’ve seen beaver coming back to the Detroit River.

So we’re seeing a lot of positives on the Great Lakes. But we still have these negatives we worry about, like increases of climate change impacts, continued changes with invasive species, vector-borne diseases like West Nile encephalitis, associated with water, and botulism in the Great Lakes. So we still have a lot of things to be concerned about.

CHRISTIE TAYLOR: And we’ll talk about all of that in the coming weeks. In the meantime, I have to let you go for now. Thank you so much, Peter Annin, director of the Mary Griggs Burke Center for Freshwater Innovation at Northland College in Ashland, Wisconsin. And Donna Kashian, professor of biological sciences at Wayne State University in Detroit. Thank you so much for coming in today.

IRA FLATOW: Great talk. So let’s talk about the book club. How can people get involved in the book club?

CHRISTIE TAYLOR: Sure. So first of all, it’s time to start reading. Go to our Science Friday– go to our website at sciencefriday.com/bookclub for all the information you need. For starters, you can even bookmark that page.

And then we are giving away 20 free copies of the book. Thanks to our friends Powell’s Books. Enter your name before Monday and you could win one free. And if that’s not in the cards for you, Powell’s is also discounting those books through the end of the book club.

IRA FLATOW: Mm-hmm. And there’s a late event in February, late February that features author Dan Egan himself.

CHRISTIE TAYLOR: Right. Our New York listeners can come in person and attend that event. And there is apparently going to be a robot fish.

IRA FLATOW: Whoa!

CHRISTIE TAYLOR: Right, we’ll learn more about that. And we’ll also be talking about the book and all sorts of related Great Lakes stories all month, including ecology, climate change, how natural resources impact–

IRA FLATOW: Do you have a favorite Great Lake?

CHRISTIE TAYLOR: I mean, I would have to say it’s Lake Superior. They are all great, but Lake Superior. It’s the biggest, it’s the deepest, it has the wildest coastline, and you’ve got ice caves. It’s glorious. It’s like a force of nature.

IRA FLATOW: Whoa, that’s great. And I’m looking forward to that book club. Thank you very much, Christie.

CHRISTIE TAYLOR: Thank you, Ira.

IRA FLATOW: Christie Taylor, captain of our good ship book club. So go to our website and get a drawing for a free copy. It’s sciencefriday.com/bookclub. And on the Science Friday VoxPop app, get started telling us your memories of how the Great Lakes have changed, or just your favorite memory of the lakes. That’s the Science Friday VoxPop app, wherever you get your apps.

One note before we go, Boston listeners, Science Friday is hosting the Great Curiosity Fair next Thursday, January 16, at WBUR City Space. Come meet book artists, immersive art makers, research scientists. Science fair. You’re not going to forget this one. Anyone under 12 can come for free. So go to sciencefriday.com/boston for tickets. That’s sciencefriday.com/boston. That’s the Science Friday Create Curiosity Fair next Thursday, January 16.

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