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July 21, 2008 6:59 AM   Subscribe

Is it possible something awful lives at the bottom of Lake Tahoe?

I recently got back from my first trip out to Lake Tahoe. On several tours of the area, the same general information was pointed to me.

A. It's about 1,600 feet deep.
B. It's fed almost entirely by streams and creeks and snow run off and is incredibly cold - about 68 degrees on the surface in the summer, and about 35 degrees way down below.
C. It's a big lake - about 75 miles around - and is one of the very few lakes of such size to not be connected to the ocean. No major rivers feed it, and it is fed by no such rivers.

I may be getting some of the specifics wrong here, but that's the gist of the information conveyed. This led one tour guide to point out (mostly for the kids, I think), that, you know, "who knows what terrific terrors lurk at the bottom of the lake, not yet discovered by modern man!"

Haha! Ha! Ha!

Except then I started to think about it - because it's very deep, very cold, and an "isolated" ecosystem - one that is carved-by-a-glacier old - what are the realistic possibilities of a unique evolutionary product being produced (and sustained) by said environment? I mean, this is a Hollywood action flick plot re-tread - mysterious creature (usually evil!) evolves in a unique, untouched environment, but is there an actual possibility of this on any scale? From 80-foot long behemoth with huge teeth to a new kind of trout?

Loch Ness seems to suffer from a similar (and obviously much more popular) myth - I assume because it is also very deep and mmmyyssteerrriouusss. Then again, it's also a loch, which indicates to me that it's actually connected to a major waterway, and that seems like a significant difference.
posted by kbanas to Science & Nature (18 answers total) 5 users marked this as a favorite
For what it's worth, "loch" in Loch Ness is different from "lock" as in waterways.

Also, Wikipedia indicates that Loch Ness is not nearly as deep as Tahoe, if that makes any difference in your theories.
posted by olinerd at 7:13 AM on July 21, 2008

Sturgeon grow big, can live in fresh water, and look kinda alien, so I'm going to use them as the starting point for some estimates. I've just done some clicking around, and found that sturgeon can eat 2-3% of their bodyweight per day. I'm going to assume we can drop that to, say, 1% in very cold water.

Anyone care to take a stab at the Minimum viable population for such a fish? I'm going to go for 750, and an average weight of, say, 100kg.

That gives us a nice easy 750kg of food, per day. Could the lake support that kind of population?

(Although I think that, if there was a population large enough to be self-sustaining, we'd have seen a carcass washed up by now).
posted by Leon at 7:39 AM on July 21, 2008

I live at the bottom of Lake Tahoe.

But seriously, it looks like the lake area formed about 2 million years ago, so who knows what evil lurks at the bottom? Perhaps a killer algae.
posted by malaprohibita at 7:47 AM on July 21, 2008 [1 favorite]

You mean Tahoe Tessie?
posted by caddis at 7:53 AM on July 21, 2008 [1 favorite]

By the way, Lake Baikal is another very deep lake with an interesting ecosystem. Unfortunately, it is succumbing to pollution and some of its treasures may be lost.
posted by caddis at 7:58 AM on July 21, 2008

I seem to remember reading something about a distinct fish population in Lake Tahoe. Tried to find it, no luck. On the plus side, I did find this quote, which suggests it's possible:

" populations of freshwater trout in the Sierra Madre Mountains of north central Mexico. These fish appear quite ancient and are genetically distinct from other populations of trout..."

That same link talks about a little research into trout in (?) Lake Tahoe, with no cool quotes about ancient populations. But it doesn't rule out what you're hoping to find, since at most they studied the trout, and even that isn't clear.
posted by salvia at 8:15 AM on July 21, 2008

In reality, no megafauna lives in Lake Tahoe. If it did, we'd know about it by now.

I'm not saying there's anything living at the bottom of Tahoe, but this is really, really terrible logic.
posted by toomuchpete at 8:21 AM on July 21, 2008

for something to evolve there has to be a population. you can't just have one big thing sitting at the bottom that slowly changes over time - evolution happens by some animals within a population dying out and others (better adapted) surviving. so there's a tension between the idea of "one big monster" and "evolutionary product" (average generation lifetime must come into it too). but i have no idea how the numbers play out.
posted by not sure this is a good idea at 8:23 AM on July 21, 2008

Ah, here's something cool (pdf). A 1974 press release from the Fish & Wildlife Service about "the endangered cui-ui (pronounced kwee-wee) sucker, a unique fish found nowhere else in the world than in Pyramid Lake, Nevada." Pyramid Lake is related to Lake Tahoe, as the press release explains. The trout stocked in Tahoe are called Lahontan Trout, and "the parent of Pyramid Lake--Lake Lahontan-- probably was born about 70,000 years ago in the last days of the ice age." So, I might be wrong here, but it sounds like whatever ancient monster lives in Lake Tahoe once lived in Lake Lahontan.
posted by salvia at 8:24 AM on July 21, 2008

Now, well its not like I've been down lower than 100 feet diving in Tahoe, but umm, no there's nothing weird down there. I was hoping to see Tessie though, some day.

There is an urban legend that the depths of Tahoe hold the nearly frozen, preserved remains of all kinds of corpses, many dumped there during the heyday of Mob control over the casinos. That would be pretty cool. Snopes (and common sense) pretty much disprove that one though.
posted by elendil71 at 8:38 AM on July 21, 2008

Some more random guessing with numbers. The surface area of the lake is 490km^2. Lets say that a hypothetical population of bottom-feeding fish live in the deepest half, giving them a range of 245km^2. If the 750kg figure is reasonable, each square kilometre of lake bottom would have to produce 1120kg of food per year. That seems to be on the high end of feasible to me, but then I don't know much about lake bottoms.
posted by Leon at 8:58 AM on July 21, 2008

Lake Tahoe is well known in remote sensing circles as one of the earliest bodies of water to undergo high-resolution swath bathymetry. Such bathymetry will image anything below the surface larger than a football. I am pretty sure they didn't notice anything out of the ordinary, but you can view all the images and do a quicktime "fly-through" here and here and here.

Also, it is well known for having experienced massive, tectonically-induced underwater landslides and resulting ca. 100m tsunamis and water perturbations (seiche waves slopping back and forth) that would have been awkward for those ichtyosaurs ... and might be awkward for sunbathers in the future...
posted by Rumple at 9:54 AM on July 21, 2008 [1 favorite]

The lake formed a scant two million years ago, is not fed by any other notable tributary, and is isolated in other ways.

In other words, there hasn't been enough time for evolution to work its magic in all but the most minor ways to shape mutant hell beasts. At most any fish stock within its waters would be only slightly divergent (and perhaps not even classifiable as seperate species) from those found elsewhere.

That's not to say that the lake couldn't be host to unique and marvelous small animals, perhaps a swarm of flesh eating crawfish which have evolved a sort of hive mind that allows them to sense when sexually active, virile teens are camping along the lake's seemingly peaceful shores.
posted by wfrgms at 10:31 AM on July 21, 2008

is two million years really too small? i had the impression (i am not a biologist) that it was possible evolution occurred in "spurts" over relatively short timescales. so even though it proceeds slowly on average, important "steps" tend to be relatively fast (and might be triggered by the kind of pressure introduced by, say, suddenly being trapped in this lake...?)
posted by not sure this is a good idea at 11:06 AM on July 21, 2008

I grew up in South Lake Tahoe (er, the town, not the water).

"Tahoe Tessie" is super-lame tour guide spew, which I believe was invented by the operators of the Tahoe Queen; nobody takes it the least bit seriously.

The lake is fed mostly from snow and tiny streams, so the fish population is based on animals adapted to that (kokanee salmon, river trout, crawdads, that's about it.) Even if you assume that two million years is enough time for river trout to evolve into monstrous deepwater beasties, you'd have to also assume that some of the intermediate steps would still exist as well and you'd have a whole food chain. Or else you'd have to explain why all the intermediate-size fish would have disappeared without a trace, leaving only the big'uns.

Also note that the water clarity -- when I was a kid you could see the bottom at 100 feet, though it's getting more polluted lately -- implies that the lake is unusually poor as a nutrient source. So any guesses based on estimated food supply should take that into account. (The fishing isn't great to be honest; I hear there are some large-ish deepwater trout to be found, but we always had better luck heading way downriver.)

wfrgms may be onto something with the sentient crawfish swarms, though; it'd explain a few things about my teenage years...
posted by ook at 11:49 AM on July 21, 2008

On the other hand, kokanee salmon are kind of nightmare-inducing in spawning season, so maybe that qualifies. (Not unique to Tahoe, though.)
posted by ook at 12:01 PM on July 21, 2008

My story-answer got nuked, understandably. But I still think my comment at the end (not fictitious) stands:

Ok ok...but the scientific world was befuddled when life was found on the edges of steam vents at the bottom of the ocean - some of the hottest climes on the entire planet (many hundreds of degrees) - if my memory serves me correctly. Doesn't seem entirely outside the realm of possibility to me that we could find the same at the opposite end of the temperature spectrum.

A couple of you mefi-mailed me about the story, I'll shoot you back the text of it (had it in browser history still).
posted by allkindsoftime at 11:20 PM on July 21, 2008

Since this question is still open, I just thought I'd pop-in to say that a friend of mine picked up the nuked story-answer for a literary mag and now its actually in print. Anyway, if you guys want info on how to get it (I actually expanded the story-line a bit with some more dialogue), just drop me a me-mail.
posted by allkindsoftime at 8:27 AM on March 27, 2009

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