Joshua Ginsberg 0:00
34 years and despite that, when he told me he was retiring, I was shocked, because I could not imagine somebody with Dave's energy, insight and passion, who would still go mucking about in streams, grabbing muscles that, as he said to me when he took me mucking about in a stream, hmm, 6070, years old, but a man with a tremendous and inordinate fondness for bivalves and mussels in particular, but is an expert and has deep expertise on invasive species, conservation biology, the Hudson River more generally, and other subjects, including restoration ecology And reintroduction ecology. Dave knows his mussels. Not only does he have a passion for our native mussels, he was doing a standardized sampling on the Hudson River, and there were a few zebra mussels in it, and a couple years later, there were a few billion zebra mussels, and Dave has tracked the rise and hopefully the fall of zebra mussels in the Hudson he had his PhD from Cornell low these many years ago, and in retirement, returned home to the state of Michigan, where he lives in an arbor and Ann Arbor, and with his wife, Judy. And as he modestly said to me, I do a little bit of science, but spent a lot of time gardening and seeking out mushrooms so in beyond the sea. Dave notes that the fresh water of this world, while a tiny percentage of all the water on Earth, is a critical resource that has been deeply abused for a very long time, the biodiversity of fresh water, as Dave will tell us, is remarkable and important, and the water itself is critical to life on Earth, full stop, no exceptions. So it is with great joy and a real pleasure to welcome Dave Strayer back to his old home and hope that you will enjoy his talk. Thank you very much.
Dave Strayer 2:20
That's sort of typical for me. Thank you, Josh for the nice introduction, and thank you for the invitation to speak here tonight. I'm especially honored to be giving the Ames lecture, because, as Josh just noted, Ned has been such a great friend of the Institute for such a very long time. The subject of my talk tonight is, is the blue planet. And I think most of you have seen this picture, the Earth looks blue from outer space because, because most of the planets covered with a blue ocean. And in fact, if you look at where the water is on the surface of the Earth, it's mostly in the ocean, right? And you see there's almost all the water on the planets in the ocean, for the moment, at least, there's a little sliver of water in the ice caps, and there's a little bit of water in the groundwaters. And this diagram also shows the amount of water that's in all the world's Lake streams and wetlands. But you can't see it because the slivers too small. It's a it's about a 100th of 1% of all the water on the planet, insignificant in in quantitative terms, that tiny sliver that you can't see, of course, is supports human life, human welfare, well being, economic activity in 1000s of ways. So it's vitally important to us, and it also turns out to be disproportionately important to biological diversity. This is another pie chart showing not the amount of water that's in the ocean and inland waters, but the number of fish species that are in the ocean and inland waters, and this sliver that you can't see in the first diagram, is more than half of the second diagram. This little bit of water that's so small that you can't see it from space, supports more species of fish than are present in the ocean. So for the next few minutes, I'm going to be talking a little bit about why it is that there are so many species in our inland waters, and show you a few of those my favorite species in there. I'm going to try to cover five subjects tonight. First, I'm going to talk to you a little bit about why inland waters are so important to biological diversity. I'm going to show you a few statistics to back up my what I just said, and I'm going to try to tell you a few cool stories, just about a few inland water species, to try to bring a little that biological diversity to life. Then I'm afraid I'm going to show you some depressed. Pricing data, about how how inland water biodiversity is doing right now, and close with a few slides talking about the potential that we have to do better. Each of these subjects are easily two or three hour long talks. Josh would not give me 15 hours. He's and so I'm just going to be skating over the surface of these and I'm going to find that frustrating, and you may find that frustrating, I'm sorry, but that's just the way it's going to be tonight. Nick if you read my book, what a good idea. So I'm going to use the phrase inland waters a lot tonight. By inland waters, I mean all of the lakes, ponds, wetlands, groundwaters, any size, fresh or salty on the planet. I know that's kind of an unfamiliar term, but we don't have a better term in the English language for this. So inland waters, it's going to be so let's start about what start with by considering why inland waters contain so many species. And I think three factors have been especially important. The first is, there's there's tons of them. They're very numerous. And secondly, these inland waters, you can think of them as islands of water floating in a sea of land and and this combination of there being so many of them, and them being more or less isolated from one another gives evolution millions and millions of arenas to develop new species in right and then also, these are not just the millions of inland waters. Are not just copies of each other or tiny copies of the ocean, but they're incredibly diverse in terms of their environmental conditions. And again, this allows evolution to fit different species to this wide range of different environments. All right, so numerous. When I say numerous, I mean numerous. So in the last few years, because of, you know, remote sensing and stuff, we can now have some idea just how many inland waters there are on the planet. There was a study a few years ago involving some carry scientists actually that estimated there about 277 million lakes and ponds bigger than a quarter acre, 270 7 million. That's quite a few. And the number of running waters rivers and streams, is a little less well known, but something like 50 million miles of rivers and streams on the planet. Now, both of those estimates are underestimates, because they skip the little ones, right? So ponds less than a quarter acre, I'm going to argue in a minute, are important to biodiversity. They're not included in an estimate. Little temporary streams, little brooklets. They're not in that estimate. And then we also have large numbers, which I use the vague term, comparably large numbers of wetlands and aquifers. They're hard to count. I don't even know how you'd count them, but the earth is also covered with wetlands and aquifers. Aquifers are geological formations underground that hold water right groundwater, and there's one ocean. So in one sense, if you look at the volume of water, the ocean rules, and if you look at the numbers of bodies of water, inland waters rule, so that we have lots and lots of inland waters. They're, they're islands. Okay, so, you know, you Google Island, I did this. You google Island, you don't get a lake. You get a picture of the same but you get the same picture. It's a tropical Sand Island with one palm tree on it, and, and sometimes, actually, Gilligan and Marianne are on it and and so that's an island, so, but, of course, the inland waters are islands in a sea of land. So this little diagram here, this is actually a map of a little bit of Dutchess County I did a few years ago. And you can see that it's sort of a photographic negative, right? And see, see, the dark are the the inland waters, you know, all these little islands and someone are sort of normal shaped, round or oval lakes. And then we got these funny shaped islands of inland waters that are sort of shaped like big spiders or or trees that are the drainage systems. And the species that live in these different watery islands are more or less isolated from one another. If you're something like a duck, that this is that you're not isolated, right? I mean, you can just fly around from one body of water to another, and the different bodies of water are more like different rooms in one house, but for say, a snail, maybe a snail. Over many, many generations, a population of snails can move all through one drainage system, but it can't get to the next one that's impossible to get to. And if you're a fish that only lives in the deepest waters of the lake, the deep, colder waters of the lake, and you're living in. This lake, this lake may as well be Mars. You're never going to get there. And so the degree of isolation, the islandness of the world, depends not on just on the geography of the waters, but also on the biology of the species. And the point I guess I've already made is there's way more watery islands than there are islands of land in the ocean. And so you see the numbers, there's about 2 million lakes bigger than 25 acres. There's 175,000 islands in the ocean of that size. So when you google Island, you should get a lake in Sweden. I'll write to the people about that. And many of you know that biological diversity is really high on oceanic islands. We have this evolution of these interesting species or species groups. You have radiation of species into new niches when they're on islands. And here's a you know, you know this, right? So there's some famous examples. Darwin's finches are probably the most famous in the upper left these, actually, I think are tanagers that somehow made it to the Galapagos Islands, and then they radiate it out. And they do all, there's all kinds of new species. They're doing things that you know, tanagers didn't do ancestrally. There's also a famous radiation of tree snails on the Pacific Islands. Many species mostly gone now and then. In Hawaii, there was many evolution of many endemic birds in Hawaii, in addition to the islands being a site of a lot of evolution, a lot of these species are very rare now because they only occurred on one island, and they're very susceptible to human impacts. And it's going to be the same thing with the inland water species I'm going to talk about in a minute.
Dave Strayer 11:44
And then finally, the environmental conditions vary a lot across inland waters. Almost anything you can think of, any characteristic you can think of, there are lakes and rivers that are like this, and there are other ones that are like that. Very, very different. So here's two lakes right, very contrasty the lake on the left is Lake Baikal. It's the largest lake in the world by volume. Contains about the same amount of water as all the Laurentian Great Lakes combined. It's more than a mile deep. It's the oldest lake in the world, probably it's 225, or 30 million years old. There's maybe 1000 species that have evolved in this lake that don't occur anywhere else in the world. So it's like Hawaii. The lake on the right is a tire rut, you know, on the edge of a field in Columbia County and and you might say, haha. What does that have to do with biological diversity? In fact, this is a characteristic habitat for clam shrimp. There are these little, interesting little crustaceans, and they live in small temporary waters, and so that's going to be wet what you know, a year like this, where it's wet out here, maybe it'll be wet for a couple months. Other years, it might not get wet at all, but it's an essential habitat for that kind of species. And some of you may know that even smaller lakes water collecting in paint cans or old tires is a characteristic habitat for species of mosquitoes that carry some of the deadliest human diseases. So even these lakes that you were just dismissing a minute ago are very important in the global picture of biodiversity and in human welfare. So the full range is important. Lakes also come in different shapes. Lakes and rivers come in different shapes. The lake on the left is called Red Lake. It's in Croatia. There's not a really good scale here. Do I have a pointer? Is this a pointer? Yeah. Okay, so this little fuzz on the top, these are mature forest trees. The wall here is 800 feet, about 800 feet vertical, and it's another 900 feet vertical to the bottom of the lake, so there's no like kiddies swimming area here. This is cottie Fonda Lake, air in the interior of Australia. It's a temporary salt lake in the 20th century, it filled with water three times it when it's filled, it's a one and a half times the state of Delaware. It's pretty big lake. It's mostly about like a lake. It's mostly about waist deep. So very different shapes, very different water chemistries in different inland water bodies. And I have to take you back to high school chemistry here to remind you about pH. I'm not going to be doing too much chemistry, just a little bit. So the pH scale, you remember, conventionally, goes from zero to 14. Seven is neutral. There's as much Alka acid as much hydrogen ion as hydroxyl ion. Here, pH is higher than seven, are called alkaline or basic pH is lower than seven are called acidic. It's a logarithmic scale. So when you go from six to five, if you'll excuse being sloppy with the water chemistry for a minute, it goes it becomes 10 times more acidic as you go from six to five. Okay. And so to calibrate this, let's see, uh. Vinegar is about two and a half. Fresh battery acid is 0.7 this will burn you if you touch it. Household ammonia is 11 or 11 and a half, somewhere in that range, most inland waters are between four and nine. That's a pretty wide range, but between four and nine the ocean is used to be 8.2 it's now 8.1 because all the fossil fuels we've been burning and they think it's going to go down to about 7.8 under the current scenarios of fuel burning and things like that, carbon that doesn't seem like a very big amount that's large enough to endanger ocean life like corals and some of the shellfish and some of the algae that make calcium carbonate shells. So biologically, a shift from from 8.2 to 7.8 kind of a big deal. So I said most inland waters are between four and nine. There are some outside that range. This is one go the right direction. This is one of the more acidic lakes in the world. This is a lake in Indonesia. It lies in the crater of a volcano. The lake water is more accurate to say this. This is sulfuric acid. The pH of this lake is 0.3 it's it's naturally 0.3 and it's about four times as strong as fresh battery acid. So you're all you should be saying right now. Why is he talking about this in a biological diversity talk? There's nothing in this lake. Some scientists went in with personal protective gear and and special sampling gear, because if you put an aluminum boat in the lake, it would dissolve. And there are four species of microorganisms living this lake. There are no animals in the lake, but the outlet of the lake on the way to the ocean. Gradually this acid becomes neutralized, and by the time the pH rises to the point of vinegar, there are aquatic insects living in the water. So there are some species that can take very acidic conditions. In fact, there's one microbe. The ideal pH is 0.7 battery acid. That's perfect for this organism. At the other end of the spectrum, we have what are called alkali lakes. These are usually in arid regions, and they don't have an outlet, and so the minerals build up in the lake, in the lake water, and especially in some geological settings, sodium carbonate, washing soda, builds up in the lake, which raises the pH. So alkali lakes are often in the range of A 10 or 1010, and a half, 11 sometimes and sometimes as high as 11 and a half. And they also are full of life, completely different kinds of things than you would have found in that Indonesian Lake. Not very many species, but still part of inland water biodiversity. And so again, remembering that the pH scales logarithmic. The range, pH range in inland waters is about 250 billion fold range in hydrogen ion concentration. And you'll be relieved to know I'm not going to drag you through the whole periodic table here, but the chemist chemical content of inland waters with respect to almost any element you can imagine, varies also in over enormous range. And you will find species that are adapted to those different chemical conditions, high pH, low pH, high salt, low salt, high arsenic, low arsenic, all over the planet. So if you'll excuse this very crude cartoon, we have a situation like this, where we have one gigantic ocean. And I know the ocean isn't uniform in terms of habitats, but it's kind of uniform compared to inland waters. The pH in different parts of the ocean doesn't go from 0.1 to 11 and a half. And versus these small inland waters, which are all different kinds. So what we get in that situation is very large biodiversity. I already showed you fish. We have a for if you look at all the animal species, or all the species that we know about in inland waters, we know of about 150,000 animal species, plus some plants and algae that are known just from fresh waters the inland brackish waters haven't been as well studied. And so there are some additional species in the inland, salt and brackish waters that are not included in 150,000 estimate. And this is what some of the groups are that are found in inland waters, a lot of insects, which is kind of interesting, because in the ocean, there are almost no insects at all, but fresh waters are full of them. And then there's a bunch of other stuff that I'm not going to go through in any detail. All in all, about 10% of all the known animal species occur in, well, in fresh waters. And so that's a lot for that little sliver that you. Couldn't see in the diagram a little while ago, and more species are being discovered all the time. So you might think that fish species in North America would be pretty well known by now. I mean, we've had fish ecologists trampling around the continent for a couple 100 years now, but in fact, since 1990 there's been 150 new freshwater fish species described from North America. That's, I think, about four a year. And so people are still discovering lots of species in our inland waters. Now, I'm afraid we scientists love statistics. We love figures. You should just be thankful. I'm not, not doing any showing you any model results or anything like that. But we like statistics. And there's probably about, I know we have freshwater ecologists in the audience and and they're going, Whoo, that's good. I like that. But I know regular people are not so taken by statistics and so, so here's some baseball statistics. I used to like baseball when I was a kid. And again, there's about four you in the audience. You don't have to identify yourselves. Who can look at that line of figures. And they go, Whoa, that guy could hit. And the rest of you are going, Oh yeah, whatever. I hope he shows us. And so what people really want to see is not the statistics. They want to see this. This is Hank Green This is Hank Greenberg, and he could hit. These are his statistics. And you can see, I love the expression on the umpire and the cancer this boy is out of here. And so I'm going to try to show you a few stories now, stories and pictures, and get past the statistics about what lives in inland waters. What I tried to do in the book
Dave Strayer 21:42
was pick out four challenges for life in inland waters and describe, tell you, tell stories about how inland water life has solved these problems. I don't have time for that tonight, I'm afraid so I picked two of them. I'm going to talk about holding your place in the water, in the water moving against the current, finding something to eat, the other two, including sex I'm not going to talk about, and I'm sorry. I know some of you came here expecting it's expecting me to talk about kinky sex and And seriously, there's a lot of seriously kinky sex underwater. But you're going to need to read it in the book. And I understand the merit bookstore will have copies of this. You can get them in a plane wrapper and everything. So, so I'm going to, I'm going to just go through quickly and tell a few stories about about how inland water, in inland water, life, manages some of the challenges faces. The first is holding your place or moving against the current. So, you know, most water ends up in the ocean. Most water that's in lakes and streams ends up in the ocean. And so you might say, well, everything's going to get washed down to the ocean. It's a problem getting upstream. This is certainly a problem. I mean, how you get over that? And so let's talk a little bit about ways that organisms that live in fresh waters, in this case, running waters, deal with the current The first is there's a lot of species are really good at hanging on tight. And so this Mission Impossible has been in the news a lot of ladies, I understand there's a new Mission Impossible movie. This is one of the most famous stunts in the earlier movies. This is, this is Ethan Hunt, our hero. Ethan Hunt climbing the exterior the I've lost its name, big, tall building. It's glass on the outside. He's got these spiffy gloves, and he's going, huh, and he's having Arthur, he's fallen, you know? And honestly, if you've seen this, you know your heart is in your in your throat, you don't know is Ethan gonna make? Are you gonna fall off and and so it's pretty good for a human this. This is much better. This is the larva, the net wing Midge, and it's got these suckers on the on its vent, on the bottom part of the animal. They have their hooks around the edges, in the piston in the middle. And so what happens this animal goes where it wants to go, and set one of those suckers down, and it pulls up the piston to make a vacuum. And that's how it holds it in place. It they're very effective. This is these are couple entomologists collecting net wing, net wing midge larvae off a typical habitat for this animal, they can withstand forces of about 1000 fold their own weight. And so what I want to see in the next mission, Impossible movie, I want to see him do this with 999, people hanging onto his ankle and and, and then I'll be impressed. There are also plants that can hang on tight. River weed is one of my favorite plants. We have only one species in the United States, and we have a lot of it in the Delaware River, some of you know the Delaware between New York and Pennsylvania, and in the parts. Of that river, if you go out to where you can just barely stand up because the current is so strong, that's where the river weed grows. It has seeds that are covered with very sticky glue, and the seed stuck to the rock can withstand currents of up to seven feet per second, which is really, really fast for a water current, and then they sprout. And as it sprout, the little root lead has got adhesive on it, and it keeps growing out, stuck to the rocks. They'll actually knit together the rocks on the stream bottom. We only have one species. I said, in the US, the tropics are full of river weeds, and this is a South American waterfall, and it's green because that's all plants and and they don't, don't have any trouble. I mean, they don't have any trouble at all growing on that waterfall. So a lot of our species in in running waters are good at hanging on. They can also be built like a race car and and be deal with current that way. This is a fish with the was with the unfortunate name of hog sucker. It was, it was not named by anybody whoever actually studied this fish or understood this fish. This fish has many of the same features that a modern race car has, so it's streamlined, right? A lot of fish are streamlined, and that minimizes drag, to keep that from from being pushed downstream. It also has, you know, a lot of race cars have these steep, angled hoods, and that is to, if you have a fast car or efficient or fast current, the fluid forces will want to lift that the the object off of the track or off of the stream bottom. And that steep hood there pushes down to keep the car, or the sucker down onto the stream bed. So you see, here's his race car nose, and then they have there's a lot of friction on the track. So race cars have these wide, treadless tires that keep them on the track. This fish has got these big fins and a flat belly that hold it down. So it's built for being in strong currents. There was a fish guy who actually said that if you take a dead hog sucker and put it down on the roof, it'll hold its place. I might just imagine these guys, these fish biologists, are out there, and they look, look a dead hog sucker. And you know, what would you do? Right? Would you walk away? It kind of smelled. And they're like, let's see if it and so apparently they're very hydrodynamic. The other thing This fish has, you see, it's camouflage. When you see these in nature, they're really hard to see. They look just like the rocks on a riffle. And it's got this lovely mouth. All the food in the stream is down here on the stream bottom, and it's got this extensible mouth here for hoovering up all the food off the bottom. And so I'm petitioning to have this fish renamed as the magnificent riffle fish. Of course, you can swim upstream. Everybody knows the salmon right here. Salmon swimming upstream. It's quite impressive. Salmon actually go up upstream as much as 2000 miles upstream. There's a group of fishes in the Amazon called the Goliath catfishes that go 3400 miles upstream. You basically run out of continent when you when you go that far. There's not that many, even Niles, only like 4200 miles long. So this is a very impressive migration indeed. And you can see that's much further than New York to LA, that these fish are going to upstream to spawn, and then the young come back down. You can fly upstream. A lot of the I said there were a lot of insects in fresh water. So if there's a waterfall in the way, a lot of the insects, when they emerge, they can get up over the waterfall in flight. Many of the aquatic insects are pretty weak flyers. Here's a real strong one. This Dragonfly is called the globe skimmer, and it can fly 1500 miles without stopping, and it's almost 4000 miles in its lifetime, which is right on the PAR, a little greater than the monarch. So a very strong flyer indeed. And not surprisingly, this species occurs on every continent except, except Antarctica. I said, you know, for a duck, different lakes are like the different rooms in a house. For this insect, you know, the continents are like different rooms in its house. I think I'll go over to Europe for a little while. And recently, people been doing genetics on this animal. And it looks like all of the populations this are single, genetically panmictic population all around the globe, which is not bad for an organism that size. You can also walk upstream. This is not at all sexy, and you might think that you know this would only be good for a mile or two, and then you get tired of walking upstream. This is a mitten crab. It's native to the rivers of China. It has a life cycle, a little like the eel, in that it breeds in the ocean, in salt water, and then the babies go up river, and they live for. Or five years, and then they drift back down. And this animal walks as far as much as 870 miles upriver. So walking works too. You don't get the publicity salmon do, but and then finally, you can ride upstream. You knew there would be mussels. I'm sorry, Josh, so this is a pearly mussel, and we have them here in our area. They have this weird life cycle. Most of their life, they spend buried in the stream bottom, and they behave like clams or mussels. They filter feed, and they kind of sit there and they they're dull. And I, I teach a class in mussel identification out in Michigan, and my, one of my students, had one. She took a picture of it and had their computer say, what is this thing? And it said, rock.
Dave Strayer 30:48
So they, instead of having free swimming larvae, like marine invertebrates, the larvae of these animals are parasites of fish, and they live for the larvae only live for two or three days, they can't swim, and they're particular about what species of fish they need. Some of them can only go on one species of fish. Some can use a few. And it seems like a really stupid life cycle, and this is what I was taught when I was an undergraduate, many years ago. And the explanation was always, well, it may be a stupid life cycle, but the females release 10s of 1000s of these larvae, and one of them happens to bump into the right species of fish. Seems like really long odds. You know you're going to live for okay, you're sitting here. Within the next two days, a white crappie is going to come over and brush you so that you get onto the white crappie, and everything's good, but that was the explanation. It turns out, that's not at all what happens. Instead, the females seduce fish, and they use a number of different mechanisms. These are the larvae of the Ouachita kidney, kidney shell. The structure I'm showing here is about a half inch long. It looks like a little baby fish, right? I hope it looks like. So here's the mouth, here's the eyes. You can even see the little muscle bundles on the side. These look enough like, oh. So what it really is, this is just a it's a lure inside. This is a whole bunch of larvae waiting inside, like Ulysses in the Trojan horse and and these look enough like fish. The guy who discovered this, Chris Barnhart, came to a national scientific meeting, and he had these in a vial. He passed them around all his global PhDs, and he said, What kind of fish are these? I'm not very good at fish larvae. We're all like they're catastomans. They're definitely catastomers. And there were several US who did this, and we all had our opinions, and nobody said those aren't fish. So they look a lot like fish, and when a fish bites them, this is what happens. It breaks open. There's Ulysses and the other Greeks, and the fish gets infected. Here's another way they do it, the females, many of them, have lures on the edges of their bodies, and this is the edge of a edge of the body of a female rainbow muscle. And it looks like a crayfish, right, I think. And so she wiggles these things. There's the that's there's where her larvae are, and her hosts are rock bass and small mouth bass, which are very, very fond of crayfish. And so what? When one of the one of the hosts, comes by and nibbles on this, she gives them a dose of larvae. This one here, there's a group called the riffle shells. There are 28 species in America. 17 are already extinct, and every other species on in this genus is on the federal endangered species list. So this is a vanishing animal, and they dispense with this whole luring thing. They actually grab the fish. So let me see if I can play this. This is a little video that Chris Barnhart did. The female actually, she is displaying a lure. You can't see it because of the way she's oriented. And she's got a lure. She's waiting for a fish to come and get to attack that lure. The host is a log perch. It's a little benthic, bottom dwelling perch, like fish. And there he is, and she grabs him, boy, there's a surprised fish, and she grabs him, and while she's holding him, then she releases the larvae onto him. When she's done with him, she releases him. That's about as far from Oh, she just releases stuff in their water and hopes for the best very highly evolved structures and behaviors. Now some of you may be saying, but there are other freshwater mussels that don't have that life cycle at all, and they do okay. So these are zebra mussels, you know, I'm sure you've heard of zebra mussels, and they have a respectable marine invertebrate life cycle in that they have these larvae called villagers. And they sweat. They're free floating. And they swim around for a couple weeks, and then settle down and you say, Well, how can they get around? They can't go upstream, they can't swim that well, how come they're so successful? And the reason they're so successful is that people do for zebra mussels, what fish do for pearly mussels. We move them around. They don't move under their own power, so we move them in contaminated boats and boat trailers and bait buckets and dumped aquarium all that kind of stuff. Okay, so let me move to my next challenge, getting something to eat. So there's lots of ways that underwater animals eat. Some of these are really familiar. We have a lot of browsers. So up here on top of the water, we have things like cows and rabbits and caterpillars and stuff like that, and they browse on plants. And we have the same thing underwater. You know, here's a snail, and these are the grazing tracks of the snail. We have some other things that are would be completely unfamiliar to you. So in the air, in the air, air is really not not dense, right? And so you don't have many organisms up in the air. There's a few birds and insects and stuff flying around under the water. The water is full of edible particles, because the water is dense enough that that organisms can float in it, right? So this is just like if you went down to the playground with your kid, there'd be like, Skittles floating around and french fries and stuff like that. And so aquatic organisms have a lot of ways of capturing these floating particles. These animals are called filter feeders, or suspension feeders, and they have these elaborate structures. This is a head of a black fly. He's got these beautiful combs for combing out little particles out of the water. This is one of my favorites. This is a net spinning caddis fly. We have lots of these in a creek here on the property. They have silk and they build these catch nets. They look like perfect little gill nets. And the animal itself lives in a retreat, also built of silk, and I imagine I'm sitting there watching TV or whatever, and they just go out every so often, and they clean the food off the net that's caught there. And that's something we don't have above. Well, spiders, sort of, everybody is interested in predators and big scary predators. We have big scary predators under the water. This is an alligator gar from the American South, and we still have them. This is an animal that actually is still doing pretty well. And the other day, somebody got one. It was 279, pounds. And they are big and scary, and they do have serious teeth. Here's another scary one. This is a European catfish called the Vels. And the Fells in this French river have discovered that pigeons are good to eat and slow to learn and and so you're going to see I hope you so there's the catfish laying off that you can see them there, right? This catfish will get to be 10 or 15 feet long. It's big fish, and they come right up onto the bank and pluck the pigeons off there, and the pigeons keep coming back. I mean, I would go downtown to the fountain and have a drink down there, but you can see this is this. I think this qualifies as a big, scary predator to me. Yeah, nightmare. There are also some, some other interesting, more interesting, I think, predators. This is an example of cooperative predation between two different species. So this is the Irrawaddy dolphin. The irrig dolphin is a freshwater dolphin that's found in the big rivers around Southeastern Asia. There's a small population that's still barely persisting in Irrawaddy River itself in Myanmar, and a long time ago, the dolphins and the people living there learned to fish together. And so what happens is these people come out in the river in their boat, and they have a stick, and they have a way of signaling the dolphin by pounding on the gunnel of the boat, and the dolphin comes over. And the dolphin then circles the, you know, rounds the fish, rounds up the fish, drives them towards the boat. The fisherman throws the their cast nets, and they catch the fish, and they split the catch with the dolphin. The the the the
Dave Strayer 39:24
anglers who use dolphins catch two or three times as many fish per hour as the anglers who, who, who do not. So this is very effective for the people, and I suppose the dolphin as well. This population is, is it may be gone now. It the last I heard there were a few dozen animals hanging on in the face of mining and netting and water pollution and so forth. Very interesting. Maybe the scariest predators are all flat worms. And luckily for you, I don't have time to discuss the flat worms tonight. These are seriously creepy predators. Predators. And if you get the book, you don't want to read this just before you go to bed. Luckily for us, these are little, tiny things, and I they're scary enough that if these were big enough to eat people, I would never ever go near the water. There are some plants that are interesting predators. You know about Venus fly traps and stuff like that. This is a very common aquatic plant. Lives around the world. Lives around here in the Hudson Valley, find it all our ponds and lakes called bladderwort, and it has these little bladders, and they're sort of semi transparent. They're very tough and leathery. And what the plant does, the plants looking for nitrogen, right? It's looking for fertilizer. And animals, we are full of nitrogen, so it needs to it's going to catch animals to get nitrogen. So it evacuates the water out of those things, makes a vacuum, and it's got a little hair near the opening of that thing. When an animal touches it, it sucks the animal in. I'm going to show you a video that's from France, and they're going to show you first real time, and second they're going to slow it down 240 fold, so you can see it. It's the fastest. There it was that was in real time. Here it is slowed down 240 fold. It's still fast. Here's this little copepod coming along. Touches the trigger. It's the fastest predatory plant in the world. Okay, so that's all the stories I can tell you. I told Josh I wanted to tell 150,000 stories tonight, and he wouldn't let me so but all of these stories is what that biological diversity means, when I say 150,000 you should be thinking all these different ways of surviving low pH, all these different ways of eating something or avoiding being eaten yourself, or dealing with low oxygen or dealing with current and that is what, is what. When I think of biological diversity. I'm thinking of that collection of adaptations and interesting stories. So okay, here's the depressing part, inland waters aren't doing very well. So I mentioned that tiny sliver that represents inland waters are vitally important to people, and we've centered our lives, our civilizations, our cities, our activities, our farms, our factories around inland waters forever here. You know this is, this is the ABO symbol, symbol over the Nile River, right? And there's London. So our activities have been focused on inland waters for a long time. Here are sort of the big impacts on Biological Diversity. All of these impacts occur all over the globe now, and they're all deadly to freshwater life. So we have things like dams, land use change, water pollution, water withdrawals, if you haven't, I'm sure most of you seen this picture. This is the Aral Sea. It was the fourth largest body of inland water in the world. This is now the aralcom desert. You know, this is like, 20 years later. So that's gone. There's biological invasions, there's climate change already here and going to get worse and over harvest of fish and other resources for inland waters. So the result is that we're not doing real well. So I'm going to show you, I'm sorry, a few more statistics. I can't help myself, and I need to explain this conservation ranking system. First. This is I'm using the data from a group called Nature serve. And these are data from North America. Nature serve recognizes eight different ranks of how species are doing their conservation is doing. Some species are extinct or probably extinct, and those are in the alarming colors here on my pie charts. The other species are ranked from g1, to g5, g1 are things that are just right on the edge of disappearing from the planet. The California condor. G5 are things that are common everywhere. Starlings and then, and I've highlighted g1 through g3 these are species that I think of as being in bad conservation trouble. So to calibrate this in your mind, g3, species that you know are spotted owls are g3 piping plovers are g3 polar bears are g3 and I'm going to regard anything that's g3 or worse as being in trouble. So the birds and the mammals in North America. These are the data for birds and mammals. You see, we have a few extinct species, and then we have a fairly large number of species that are in real serious trouble, about 9% of the birds, about 18% of mammals. You know this probably, I'm sure we have birders in the audience, and you know, there's been a lot of press about real serious problems with. Bird populations lately, inland water species are doing worse than this. So here are data from species that are pretty mobile. These are species that can get out of harm's way a little bit, and are species that can recolonize an area after things have been destroyed, and then get better. So I've got data here for fish, stone flies and may flies. And you can see for all these species. Again, we all these groups. We have a few extinct species, not very many, but we have a pretty large number of g3 and worse species. These are the ones in the exploded pie slices, somewhere between a quarter and a half of all the species in North America are doing as badly as the spotted owl and the polar bear. Big numbers of species, the freshwater species that are cannot that are less mobile than that, and these are basically the shellfish are doing even worse. These are the pearly muscles that I just talked about, snails and crayfish and in these species now we're starting to see large numbers of extinctions, about 10% 10% a lot, about 10% of North American snails and mussels are gone, gone from the plant. They're extinct. And we have very, very large numbers going out to g3 now we're talking about half to three quarters of all the species are doing as bad or worse than the polar bear in the spot at all. I mean, it's a minority of species that are doing better than polar bears, and so that's pretty bad. And I think I'm going to kind of half skip over this, but that was statistics. And again, each of those endangered or extinct species has an interesting story that I could tell you. And I think I'm going to skip this. There's, here's an interesting story. Just take it as read that there are a whole bunch of interesting stories associated with these. So I want to close with with what's the future look like for freshwater biodiversity. And I can give two answers to this. One is really easy and the other one is real hard. So the easy answer, if we keep doing what we're doing, I am very, very confident that we are going to continue to see freshwater inland water biodiversity decline sharply, and decline more sharply than marine and terrestrial biodiversity. We are going to lose 1000s of species to extinction, probably if under a business as usual scenario, and many, many more species will decline to the point where they're ecologically or economically irrelevant. I mean, they won't be extinct, but there won't be enough of them to do any good. However, the harder, the harder answer is, well, if we take some if we start valuing this biodiversity and taking some effective actions to conserve it.
Dave Strayer 48:02
Things can be a lot better, and one of the sort of double edged well, also one of the reasons for inland water biodiversity is doing so poorly is we've done things like dams and land use change and species introductions and pollution without much regard to biodiversity. We wanted to make hydropower. We wanted to make a navigational highway up the Mississippi River. We wanted to get rid of all that chromium waste from the plate plating plant. And we did all those things just with one one objective in mind, without thinking of the broader consequences of our actions. So that's bad, right? The good side of that is because we've done such a poor job in the past, there are just very, very many opportunities to do a lot better in the future. And I don't have enough time to go through a lot of these, but I want to show you a few to leave you with a sense of the size of the opportunities that we have. The first thing is, we can be more efficient in the way we use water. So here's a local example. Some of you probably know this one about 1980 New York City decided they were running short on water. And some of you may remember there was talk about building another, another, large reservoir in the Catskills, there was talk about re a reactivating the Chelsea pumping plant and using Hudson river water. There was a lot of push pushback politically on both those suggestions and for whatever reason, New York City decided they were going to be more efficient at using water, and so they did things like metering water so the people paid, but for how much water they used, instead of just a flat fee, they fixed leaks, and they were enormously successful in increasing efficiency in New York City water use. So okay, so here's time 1980 to almost the present. These are data from the DEP down in New York, and this is the amount of water the whole city used. Light in black, and this is the amount of water per person. You get the same exact pattern. And you can see that New York City of today uses 1/3 less water than it did in 1980 and I don't think, if you go to New York City, I don't think feel like you're suffering, right? You can flush toilets, you can have a drink, you can hose down the sidewalk, you can do all those things, and we have similarly large opportunities to be more efficient in water use, in cities all across the country and all across the world, in agricultural use. So we can do better with that. Sometimes we can not just prevent ecological damage, we can repair it and reverse it through ecological restoration. This is a famous large scale example in Central Florida, the Kissimmee River. In the 1960s somebody decided it would be a great idea if the river, instead of being all curvy and inefficient like this, was nice and straight. And so they built a great big canal down there. And the idea was to convey all that water down through Central Florida, get it down to Okeechobee, into the ocean in a big hurry, and it was just a disaster. They've had all kinds of problems, ecological, economic problems, all down through the Kissimmee Valley, Okeechobee itself, all the way out to the ocean in the Gulf of Mexico. And so the Corps of Engineers, this is weird recently, I guess, starting in the 90s, when they rebuilt, rebuilt the old river. So they undid all the work they did in the 60s, up in the 90s. So this is now the new Kissimmee River, with all curvy and nice and all this nice wetland, forested wetland habitat and everything next to it. This is, this is the filled in Kissimmee canal. And so we have opportunities to restore ecosystems. This is hard to do. We're getting better at it, and the more of it we do, the better we'll get at it. So we can do that. We can we can propagate very rare species now in the laboratory and reintroduce them into the wild, and this is something that's being done routinely now. Hatcheries that used to produce brown trout for stocking in Tennessee are now producing gilt darters, or something like that, little rare darters for stocking back into the wild. Pollution Control. There's terrible pollution in a lot of the world. We in the US, the Clean Water Act and Clean Air Act were enormously important in making reducing pollution. This had large benefits to human well being and economies, I mean, and also to biodiversity. Here's an interesting project I ran across. We were in Gainesville, Florida, a few years ago, Gainesville had a problem. They were releasing too much nitrate into the Florida aquifer. That's where their wastewater went. Nitrate is kind of hard to get rid of in a sewage treatment plant, and so they had a choice. They had to either build a high tech bricks and mortar, fancy treatment system, or a wetland. And they built a wetland. This is their sewage treatment plant right here. It's 125 acre constructed wetland. They actually re flooded an old drained wetland just south of town. And they're they're effluent now is almost completely free of nitrate. Solved that problem. The interesting thing is, this is a super popular place to go hiking and bird watching in Gainesville. We were there in a day in a day in January. Was hard to get a parking spot there, and so people are voluntarily walking through a sewage treatment plant. And I thought that was cool. Example. People usually think biological invasions are just impossible. We have global, globalized economies. We're going to move species around, too bad. And that's not true. If we choose to engage, we can reduce invasive species invasions. And actually, Gary Lovett here at the Cary was doing some really important work on reducing forest invaders. So here is another example of how this can work. This is in the Laurentian Great Lakes the St Lawrence Seaway opened in 1959 the graph here shows the number of shipping related invasions into the Great Lakes by the late, say, the 1980s this was rising to intolerable levels. They were getting two or three new species a year. Some of them were really problems, zebra mussels, quagga mussels, round gobies. And the people around the Great Lakes got together and they stopped it. This is the states and provinces around the Great Lakes, not the federal governments. The states and provinces got together and said, Look, you can't bring a ship into the Great Lakes unless you treat the ballast water first. They did not shut down the shipping industry. They did not impose undue burdens on the shipping industry. They just did shipping smart. And so what we see this during it took a while. This is the period the regulations came into into play. And you can see this graph heal over so there are now no new shipping related invasions in Great Lakes. If you extrapolate where this curve was going, you. So these regulations probably prevented dozens and dozens of new invasions into the Great Lakes, and some of those surely would have been problems. So we can do better if we engage, but we have to engage, and so this is part I'm a little uncomfortable talking about this, because I'm not a behavioral psychologist or a politician or anything, but I want to give you a sense that there are a lot of things that we can do to engage, to help inland water, in the bio, inland water, biodiversity, personal actions. You've probably actually heard all these things on this personal actions list. You can use less water. You can use, especially if you live near a body of water. You can, you know, don't put a lot of fertilizer and pesticide in your lawn. You don't flush your medicines down the toilet. Thing. And one thing that's not on the list, I think needs to be on the list is share your enthusiasm with other people, especially kids. Take a kid down to catch crayfish or something like that. That's good. There's some things you can't do by yourself. I don't think. I don't I don't see how I personally can do anything about the destructive new dams on the Mekong River. I need help with that. I need to get together with other people. So I want to remind you that there are a bunch of collected, collective actions we can do. You can engage with politics. And I know this is a weird time to engage with politics, but there are other levels other than the federal level, where important environmental decisions are made. So you can you can support pro environment candidates. You can write to your elected officials, thank them, chastise them, whatever is appropriate, you can speak at hearings, you could submit comments, all those things you can do that's kind of confusing. And for me, at least, there's so much going on politically that it's hard to keep track of that. And so I think one very effective way of being engaged politically without being a political junkie, is to support an organization that does the good work. And there are a whole bunch of organizations like that. I'm deliberately not naming them right now, because I'm going to offend somebody. But there are lots of good organizations that advocate for the environment in the political arena, that
Dave Strayer 57:16
that buy and protect key habitats, that sue the bad guys, which is especially important right now, I think, and that do the fundamental research under that underpins wise management educate people. And I have to point out, I'm sorry, Josh, that the Carey Institute does the fundamental research that under man, underpins wise management and educates people about ecology. So if you're really looking, don't know where to support. You know this, this we, we do a lot of and I don't work for the care anymore, but we do a lot of good work here. So there's just lots of places to engage. When I if, if we, if you, if we all don't engage, somebody's going to give this talk in 30 years or 50 years, and there's going to be a lot fewer stories about the amazing inland waters and the life they support, and a lot more of those stories about what has disappeared. Thank you. Applause.
Dave Strayer 58:41
Thanks. Thanks for Thanks, thanks, Josh. Do we have time for questions?
Joshua Ginsberg 58:49
Yeah, we have, sorry, we have time for a few questions. Let me just note one thing. There is only one copy of Dave's book left. That's the bad news. The good news is on your way out. If you write down your name and phone number, Merit books will take an order and make sure you get one. We're going to take some questions from the room. I apologize to those of you out there. We don't have too many questions online. If you put a question online, we will see if Dave or one of our distinguished colleagues can answer it for you. So, sir, you talked about the damage to the species
Speaker 3 59:23
because of all this activity. Can you talk a little bit about the chain of events that goes from what you described to the
Dave Strayer 59:36
food supply? So the question has to do with, I think the consequences of some of the losses that I've talked about, I you know, I didn't talk about the importance of fresh waters or biodiversity to people directly, but they're connected this. Biodiversity is connected to people in tons of different ways. 90s, we were just my wife and I were just in Cambodia a couple months ago on the Tonle Sap. That's a big lake there. 60% of the animal protein in for the people of Cambodia is supplied by that lake. The dams that are going up on the Mekong River are going to change the flow patterns in the Mekong in a time they sap in a way that will probably badly damage what is left of the fish populations in the Mekong. So that's why people always think of fish, and that's just a very striking example of that. There are many freshwater organisms that are connected with human disease. We don't have very many of them here. We're lucky, but things like Schistosomiasis and malaria come from freshwater ecosystems, and so the state of the freshwater ecosystems is linked like this to human health. And you know, another talk for another hour. Could it? Would could cover those linkages, but they are many, and they're strong. In
Speaker 3 1:01:09
the long run, would it not be possible for us to think along the lines of birth control and family planning to lower the carbon footprint as well as the nitrate footprint that is underlying so much of the demand nowadays for hydropower and highways and all the other things that ultimately impact wetlands.
Dave Strayer 1:01:37
So the question had to do with, if I paraphrase a little bit, using control better, controlling the human population, to control the size of its footprint. And I would say, and partly this is a question, again, that this political as much as biological. So remember, I'm not an expert at some of this stuff. I'd say two things. The first off is that rapid human population growth is happening mainly in Africa right now, and we are already committed, because of the demographic lags in a long lived human population to most of that population growth. I was a talk from a un demographer a few years ago, and we are already committed to to a few billion more people, regardless of what we do today. I agree with the sense of your your question about being more deliberate about controlling these impacts, but, but I think that that birth control sorts of things will have less of an impact than you think they ought to, because people live for so long. The Other Side of of the footprint question is the per capita impacts, and that's economic growth, not population growth, and that is going to be what is driving a lot of the increases in demand? I don't know what to say about that, because I'm not an economist. I don't know how we convince people to consume less. The only part I'm comfortable saying, really, is that there are smart ways to do these things and stupid ways to do these things, and we've been doing too many of the latter. There was a really interesting case a few years ago there. It's likely we're going to see a lot of dams in the Amazon. They're going to be very damaging to the high biodiversity there. And there was a group led by Alex Flecker up at Cornell, and they said, Well, suppose we concede that we're going to need some number, 5000 megawatts of hydropower, some number, where would we put the dams to minimize biological diversity? That's not a question that's historically been asked by the hydro engineers. And so they actually came up. There's a paper in Science a few years ago where they came up with a configuration of dams that would satisfy the hydropower and cause less damage to the biodiversity. Dams aren't good for biodiversity. They're never going to be good for biodiversity. But we can have a case where we can have this impact, or we can have five times that much impact. And that part, I feel confident about saying we need to do better, and we can do better, so
Joshua Ginsberg 1:04:21
I'll take one more question and suggest that Dave has 149 hours more to talk to us, which will cover our Friday nights at the carry for the foreseeable future. Anyone in the back you touched on this briefly with your reference
Unknown Speaker 1:04:37
to the tire
Unknown Speaker 1:04:39
tracks, but could you comment on the role of vernal
Dave Strayer 1:04:44
pools? Yeah, vernal pools are really interesting, and they're kind of coming into their own right now, vernal pools are small, usually small ponds that are filled only for a couple months in the spring, around here in the spring, right? And then they have. Characteristic group of species that live in them, that that are adapted. They can, you know, be wet for a while and dry fall. Really interesting if you have not gone. Do you guys do vernal pool walks here? Yeah, okay, so watch for a vernal pool walk. There's some really interesting species that you should see. You think it'd be a stressful environment. But when you go to a vernal pool, the first thing that always strikes me is how full of life they are, and so they're just full of fairy shrimps and little clams and stuff like that. And historically, they've been undervalued. All wetlands have been undervalued historically, and we get rid of them. And that's true of vernal pools as well. In Michigan, they've taken to calling the coral reefs of the forest. I'm not so sure about that, but they're really interesting, and they're part of the portfolio of freshwater or inland water biodiversity, containing species that aren't found anywhere else. It isn't like you're going to find fairy shrimp and the Hudson, you will not
Joshua Ginsberg 1:06:04
so. Thank you all for coming to the net Ames Lecture and Dave, thank you For a marvelous lecture. Applause.
