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Welcome back to SciShow Talk Show! This week we introduce our guest, Heidi Sedivy who will be talking about invasive mussels as well as Montana native mussels.
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Hank Green: Hello and welcome to another episode of the SciShow Talk Show where today we've got some weird things coming and we are joined by Heidi Sedivy. Heidi, what is it that you do?

Heidi Sedivy: I do education outreach for the Flathead Lakers up at Flathead Lake. We're the largest lake west of the Mississippi, in case you didn't know that!

HG: I did, we were talking about this beforehand.

HS: Not east of the Mississippi?

[HG laughs]

HS: Yeah, and we're the last watershed in the United States without these mussels.

HG: So, what, they're...

HS: These little guys are quagga mussels.

HG: Quagga mussels.

HS: Or "QWAH-gah." "QWAH-gah." I pretend I'm from Canada sometimes.

HG: Are these... are these not zebra mussels?

HS: No.

HG: Those are different.


HS: Zebra mussels are a close relative, so they're in the same genus. Um, different species. These are quagga mussels out of Lake Mead. Um, the scary part is we get our drinking water from an aquifer.

HG: Yes, we do.

HS: Really clean, we're really lucky.

HG: That's why I love my water.

HS: Um, well Las Vegas actually gets a lot of their drinking water directly from Lake Mead.

HG: They have to filter out the little... the little spores, I guess.

HS: Filter it, and it's... it's a lot, it's a big process. It's an expensive process. We are really, really fortunate not to have these mussels.

HG: So what, what am I... What am I looking at here? What happened?


HS: This guy on Lake Mead decided he wanted to start a business selling educational materials --

HG: Oh, okay.

HS: -- so he took some of these pipes, and he put them... They like deeper water so probably thirty feet down, and he just let them sit for six months. And they like little holes, they don't like the sunlight, so these were probably down like... that.

HG: Yeah.


HS: Uh, um... [laughs] And then they just sat for six months, and this is how many mussels can get on a pipe within just that six months. They grow fast, their lifespans are three to five years, so they don't live that long, and then they have huge die-offs, and so then all of these mussels die at the same time, they wash up on the beaches, and you can feel how sharp those are? That's what your beaches are. So also if we get those in the Flathead area or anywhere in the northwest --

HG: Yeah.

HS: -- then this is, this is what we walk on.

HG: That makes the... that makes the beach a lot less fun.

HS: Yeah, yeah, and so people go through a lot of Band-Aids in the Midwest.


HG: And then, what, he just lacquers them?

HS: And then he, he bakes them first [laughs] in his own personal oven. [laughs]

HG: To get... To get all of the...

HS: "Honey, what's for dinner?"

[HG laughs]

HS: Um, and even in a lot of states you can't possess dead ones because to monitor for these we do EDNA, electronic DNA sampling, and dead mussels will set off a false positive, and so even in the state of Montana, um, you need to have permits to even have these dead ones, yeah, yeah.

HG: Wow.

HS: So we're really careful. We don't want false positives, we don't want... So, even if you know you have a boat, and you have mussels on it, you know they're dead, if you launch your boat even those dead mussels could cause a huge issue. Not as big of a problem if they were alive, if they were alive it would be...

HG: A bigger issue?

HS: ...A much bigger issue.


HG: So, invasive species... are a huge problem...

HS: Everywhere.

HG: Yeah, all over the world. How do these guys get transported? So how, like how do you, like, get from one lake to another?

HS: These got to the Great Lakes in a ballast tank. Um, from... prob... the Caspian Sea is where they're native to, the Black Sea and the Caspian Sea. So they came over on ballast tanks in the late '80s.

HG: So these big tankers just fill up tanks to make the buoyancy correct...

HS: Exactly, yeah.

HG: ...and then dump it when they...

HS: ...Get their cargo. Cargo weighs 'em down. They empty into the water. That was in the late '80s, and in 2007 they got west of the Mississippi in Lake Mead. Um...

HG: So this is, these are from, these are from Lake Mead and that happened in 2007.

HS: Exactly, yeah.

HG: Wow.


HS: Yeah.

HG: So do they know how... did that just, like, happen, like, somebody took their boat from, like, overland...?

HS: That's really the only way they spread, I mean they obviously, they don't have feet, they don't...

HG: Right. They don't run across the land...

[HS laughs]

HS: What, like, "oh it's overcrowded here!"

HG: Exactly!

HS: ...and they go find a new lake!

HG: How is there, there's not like birds, like, picking them up and dropping them?

HS: They have done studies and they haven't found that birds can do that, um...

HG: So it's all human transport.

HS: All human transport, and... they can live outside of the water for thirty days. So if you have your boat in the water and an adult mussel attaches to it, then thirty days, it could still be perfectly fine, and that's plenty of time to get to Montana, or wherever. And the baby mussels are called veligers, they don't have little shells, so each one of these mussels can produce one million babies a year, well, all the female ones... So that's how they also can reproduce so quickly, and they don't have any native predators. So the little baby mussels don't have shells, but they can still live in standing water for about a week. And so even that week transporting and just your... your bilge, if you have water in your bilge, or your livewells, or anything... you could have these species there and not even realize it. A lot of people will just, you know, if it's just on their life jacket, and they're just saying, "well, we cleaned our boat, that's great," well maybe you didn't clean your life jacket, so...


HG: So like, just like, just... they're tiny, these things.

HS: Microscopic.

HG: Yeah. So they're just, they could be just in...

HS: Anything.

HG: Yeah, that's...

HS: Scary.

HG: That seems like an impossible battle to fight, to me.

HS: ...And a lot of people say that, and it's not impossible...

HG: But I mean, so far we're clean.

HS: We're good. And a lot of thing is just always exercise precaution, so even though I can tell you that Flathead Lake is clean, and I'm fairly certain it is, there could be things in there that I don't know about, so even if I leave Flathead and go somewhere else I'm going to clean everything and pretend that it does have it, because we don't know for sure. Um, there are lakes that they'll find mussels and they'll take the water level down and realize that they've had mussels for years, and so all those boats are going back and forth, um... that's not a very common case, but it, it could happen, so always practice due diligence.


HG: Right. So I'm looking at this, and what if I'm just saying, "well this just looks like a lot of good bird food, and fish food, and, you know, just more... more life for the lake. What's the big problem? Are, are they out-competing other little mussels that I don't care about?"

HS: They... they attach to other mussels, and right around the seam so other mussels can't, can't eat.

HG: The little jerks!

[HS laughs]

HS: So, and so they actually will starve, will starve the native, the native mussels and clam species. There are pictures, they can actually attach to crayfish claws and then the crayfish can't use their claws. They've attached to, I mean dragonfly larvae, they'll attach to anything, they will attach to aquatic plants, um or... Anything that they, they have byssal threads, so that's these little threads, um, on their butt that can attach to anything, and no native mussel can do that, at least in Montana, so if you see any mussel that's attached to anything it's not a native mussel. Um, and so those byssal threads give it a huge competitive advantage and they're not palatable, they don't have any native predators, so nothing here can really eat them. They did try bringing in a native -- or a fish from its native place --

HG: That eats them.

HS: Um, and now that, the round goby is an invasive species, so yeah...


HG: Oh, good job us!

[HS laughs]

HG: It's a common, it seems like a common story.

HS: Yeah, it really is.

HG: And so economically, so like that... it sort of seems like a disaster environmentally, is, are there economic problems? I would think there is.

HS: There're... I mean, if these got into a hydroelectric --

HG: Right.

HS: -- power facility, then each turbine has to be cleaned annually and they sometimes will try these in chlorine, but that's not good for the water. They're testing all sorts of things right now, um, hot water is the most efficient. But you're talking thousands, tens of thousands of dollars per turbine, per dam annually because you, you can't get rid of these once they're here.

HG: That sounds like an expensive problem.


HS: It would, ah... Idaho, it would be about a hundred million dollars a year, in Montana it would be... greater than that, so...

HG: Well that sounds like if, if we were to properly, uh, put the, put the economics to bear on this then we would, we would spend a lot of money trying to stop this from happening.

HS: Oh, oh yeah, this is the case...

HG: Is that happening?

HS: Um, it is. It's happening more and more, we're seeing it, um, we're doing a lot of prevention efforts, uh, we started out with just a few boat inspection stations in 2007, 2008. We now have I think over a dozen permanent boat inspection stations. Boats coming into Montana have to be inspected. Um, so yeah, a lot of money is going towards that prevention.

HG: That's great.


HS: Yeah...

HG: That's great, so, uh, how would you gauge Flathead Lake's health at the moment?

HS: It is one of the cleanest lakes in the nation. Good. Yeah!

[HG and HS high-five]

HG: Well this was super-fascinating, um, and it's great to have these sort of, you know, treasures here in Montana, and to have people like you protecting them, so thank you for coming on the show.

HS: Thank you. Thank you for having me.

HG: And thank you guys for watching. If you want to keep getting smarter with us here at SciShow you can go to and subscribe.